Physics World

Astronomer Jessica Dempsey has become director-general of the Square Kilometre Array Observatory (SKAO), which will be the world’s largest and most sensitive radio telescope when it opens next year. Dempsey will now serve a five-year term as director-general and succeeds Philip Diamond, who held the role since 2012.

Three decades in the making, the SKAO is based in South Africa and Australia and consists of 197 dishes and 131 072 antennas to study how galaxies form, the nature of dark matter, and whether life exists on other planets.

The Australian side, known as SKA-Low, will focus on low-frequency obervations, while South Africa’s SKA-Mid will observe mid-range frequencies.

The headquarters of the organization is based in the UK at Jodrell Bank and SKAO has 13 full members, which includes China, Germany and India.

From film star to the stars

Dempsey studied both astrophysics and theatre and film science as an undergraduate at the University of New South Wales before becoming an actor in the late 1990s.

Dempsey then did a PhD in astronomy at UNSW, graduating in 2007 before working at the James Clerk Maxwell Telescope at Mauna Kea Observatory in Hawaii, becoming operations manager in 2012 and then deputy director of the telescope in 2016.

In 2022 Dempsey became director of the Netherlands Institute for Radio Astronomy and throughout her career has championed more equitable opportunity and experience for women and all underrepresented individuals in science, in 2023 becoming professor of ethics in astronomy at Radboud University.

Dempsey says it is “humbling” to lead the organization and is “passionately dedicated” to its success.

SKAO is currently preparing for the start of “science verification”, in which astronomers will gain access to the first SKAO data. This is due to begin for the SKA-Low telescope in Australia in the second half of 2027.

“As someone who loves nothing more than building and running telescopes, there is not a better time to be asked to take up this role – we are just getting to the cool stuff,” adds Dempsey. “This is a daring project, unprecedented in scale and scope, and it will need the skills of every single team member on three continents and all the support of our broad global partnership to see it come to light.”

Diamond, meanwhile, noted that the observatory is in “very good hands” with Dempsey’s appointment.

“This is a demanding role, with the need to balance scientific, political, diplomatic, financial and many other considerations,” adds Diamond. “I have full faith in [Dempsey’s] ability to lead this extraordinary organization through its next chapter.”

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From heatwaves to extreme rainfall, the impact of climate change is rapidly becoming a reality in our daily lives and a danger to our planet. But physicists are in a great position to help, with physics-based research bringing about practical, real-world solutions, whether it’s more efficient solar cells, better climate models, or novel materials for capturing carbon dioxide from the atmosphere.

There are huge economic and commercial benefits from such work too. A 2023 report from the Institute of Physics (IOP), entitled Physics Powering the Green Economy, estimates there are almost 1800 companies in the UK and Ireland taking green technologies to market with a combined turnover of £750bn.

Last year a follow-up IOP Impact report entitled Unleashing Physics to Power the UK Energy Sector identified the most promising physics technologies for transforming the UK’s energy system. These fall into three main areas: energy generation (nuclear power, photovoltaics), storage (batteries) and transmission (high-temperature superconductors).

The clean-energy revolution will not be easy, however. As the IOP report points out, the UK has a strong research base, good international collaborations, and a growing pipeline of spin-out and early-stage companies. But the country doesn’t invest enough in technology scale-up facilities, faces critical skill shortages, and isn’t great at recycling either.

To discuss how physicists are supporting the green economy – and what more they can do – a panel debate was recently held at the IOP in central London. Attended by Prince Edward, the Duke of Edinburgh, as well as about 100 business leaders, policy chiefs, senior physicists, and IOP and IOP Publishing staff, it was chaired by Tara Shears, the IOP’s vice-president for science and innovation.

The panel featured ex-BP boss John Browne, who now works in green energy, Emily Nurse from the UK’s Climate Change Committee, former Sizewell C energy-strategy director David Cole, solar-cell physicist Jenny Nelson from Imperial College, and Nellie Technologies founder Stephen Milburn. The following is an edited extract of the discussion.

Physicists for a greener future

John Browne is chair of BeyondNetZero, a climate-growth equity venture firm. He was group chief executive of energy giant BP from 1995–2007, having joined the firm in 1966 after studying natural sciences.

Emily Nurse, who was originally an experimental particle physicist, is the director of net zero at the UK’s Climate Change Committee, which advises the UK government on reducing emissions and adapting to the impacts of climate change.

David Cole, an engineer by training, was at the time of the discussion director of energy strategy at the Sizewell C nuclear-power plant, which is being built in Suffolk in the UK. When complete, it is expected to meet up to 7% of the UK’s total electricity demand. He is now executive president, consulting, at energy firm Wood.

Jenny Nelson is a physicist at Imperial College London, where she has spent almost 30 years developing advanced materials for photovoltaic solar cells. She is also mitigation programme lead at the Grantham Institute of Climate Change and the Environment.

Stephen Milburn is a physicist who is founder and chief executive of the firm Nellie Technologies in South Wales. It removes carbon dioxide form the atmosphere using biomass, which can then be used as animal feed or construction material.

What role are physicists currently playing in our quest for a greener economy?

John Browne: I made a wonderful decision 60 years ago, when I was 18, which was to read physics. After graduating, I became an engineer, but over the last 30 years physics has come back in to my life as I’ve found myself doing something very important – trying to get to net zero. Physics, you see, touches absolutely everything.

All that I’ve ever done – whether it’s renewable energy or “old energy” [fossil fuels] in my old life – starts with physics. Whether you’re involved in chemistry, biology, electronics or engineering, it could not exist without a much deeper understanding of physics. We have to make sure everybody knows that – but I don’t think people currently do. They tend to think engineering is the only enabler for commercialization, but physics is there.

Emily Nurse: I started out as a particle physicist working at CERN on the Large Hadron Collider but for the last four years, I’ve been involved in climate policy and now work with the UK’s Climate Change Committee. We are the UK government’s official advisers on its climate targets – and assessing progress towards meeting those targets. As we celebrate global decarbonization to date, we need to remember it’s all underpinned by physics.

Take the rise of solar power for example, which has been the fastest growing source of global electricity generation for the last 20 years in a row. Solar installations in 2024 were double those in 2022. Along with wind, solar has led to a reduction in electricity from fossil fuels. We’re seeing the costs of solar plummeting and they just keep falling further.

In the UK, solar power has been growing more slowly, but it’s starting to pick up and is going to be a really important part of the electricity mix. We’ve also got a lot of wind here in the UK – it’s a very windy island after all. I would also like to give a shout out to heat pumps: as a physicist, how can you not love their efficiency?

David Cole: I am an engineer, not a physicist, but I’ve spent my career in lots of different sectors and been fascinated with the role that energy plays in creating a better society. What’s really interesting at Sizewell C is the ownership structure, which involves both state and private investment. It’s the first time private investment has been used for a new nuclear build in the UK.

I hope it leads to a virtuous circle, in which the more plants we build, the more we can reap from that investment

David Cole

Getting this hybrid financial structure over the line was not trivial – it took a lot of effort – but I think it will drive great performance. We’re also trying to use as much UK content in the plants as possible, whether that’s materials, skills or technology. I hope it leads to a virtuous circle, in which the more plants we build, the more we can reap from that investment. Sizewell C will, in other words, bring down energy costs, which is fundamental to economic growth.

Jenny Nelson: I have been active in research into solar photovoltaic (PV) materials and devices for over 30 years and we should celebrate how much has happened in the field during that time. In the last 10 years, we have seen capacity increase globally by more than a factor of 10, we’ve seen the efficiency of solar cells increase, and we’ve seen the cost come down almost by a factor of eight, all of which is remarkable.

Those innovations are firmly rooted in physics – whether it’s changes in device structure… or of the optical properties of materials

Jenny Nelson

The cheapest form of electricity globally, in other words, is now from solar PV, which was not the case 30 years ago. These developments have come partly from economies of scale and partly from technological innovations that have now fed through into production. Those innovations are firmly rooted in physics – whether it’s changes in device structure due to our understanding of semiconductor physics or new developments in the optical properties of materials.

The next generation of PV cells, which are likely to be silicon-based tandem devices, will also depend on scientific breakthroughs and innovations.

Stephen Milburn: I’m chief executive of Nellie Technologies, which is based in South Wales on the site of a former chemical-weapons storage facility. We’re using biomass waste for removing atmospheric carbon dioxide, and if you visit us, you’ll see all kinds of activity: in one corner there’s chemistry, in another engineering and in the next there’s biology and biochemistry. But physics is at the heart of the technology. Physicists are a bit arrogant when we say we think we can do everything, but the fact is we probably can.

But we should also celebrate the work that has gone on to create a market in which carbon-emission credits can be bought and sold. Trading carbon credits has been a bit of a dark activity over the last 10 years, with double counting and bad things happening purely by firms wishing to make a profit. However, the market does have the power to regulate itself – in fact the alignment we’re starting to see between the UK and the EU will help greatly.

What are the biggest growth opportunities for the green-economy sector?

John Browne: First, we can do much more with what we’ve already got – for example we could increase our offshore wind or rethink whether we should go back into onshore wind. Second, we can improve what we’re doing – for instance, by increasing the efficiency of solar panels to their theoretical maximum, which would make rooftop solar economically attractive. Third, there are new opportunities, such as metallic organic frameworks and nuclear fusion.

What we do here in the UK needs to move the needle globally, which means thinking about how to scale and finance it properly

John Browne

However, the UK needs to avoid doing things that others are doing much better. The race for the best battery in the world is, for example, probably going to be won elsewhere. What we do here in the UK needs to move the needle globally, which means thinking about how to scale and finance it properly. The UK shouldn’t end up as a secondary player.

Emily Nurse: The UK has made a lot of progress in our quest to reach net zero by 2050. Since 1990, for example, we’ve halved our carbon emissions, mainly by decarbonizing electricity – phasing out coal, reducing gas generation, while significantly increasing wind, solar and other renewables. Electricity generation now accounts for only around 7% of UK emissions, which are dominated by transport (cars and vans) and heating (oil and gas boilers).

Reducing emissions still further will predominantly come from moving to electric technologies, including electric vehicles and heat pumps, and by further decarbonizing the electricity supply. There will be a backbone of wind and solar, but to ensure a secure supply, we’ll need nuclear, carbon capture and storage, hydrogen and batteries. We’ll have to reduce emissions from agriculture and land use too.

A report from the Confederation of British Industry (CBI) last year estimated that the net-zero economy grew by 10% in 2024, which is three times faster than the rest of the UK. But we’ll need more innovations to continue to bring costs down – and we’ll also need to provide incentives to boost the take-up of electric technologies. If we do that, there’ll be an overall saving to the UK economy in about 15 years’ time, our analysis suggests. There are huge opportunities for green growth to come from this investment.

David Cole: I agree that for the UK to be competitive, the cost of energy has to come down – not just for domestic customers but businesses too. In fact, there are two main opportunities First, we have to adopt a “whole-systems” approach. If we’re building a power station, for example, can we use every bit to its maximum potential?

Let’s say I’m running a direct air-capture plant operating at 25–30 ºC – can I use the waste flow from my coolant system to encourage new industries? Can it support nearby hydrogen generation plants or companies making, say, synthetic aviation fuel? Those questions involve thinking about physics and engineering as well as materials science, which is also super important.

Whichever way you look at it, we’re talking about building a lot of hardware, which involves materials. How much energy per unit mass are they using? Can we recycle those materials? What can we do with the waste products? Ultimately, what is really important is energy security: where does your energy come from, who made it and what impact does it have on the environment?

Jenny Nelson: The net-zero economy is growing significantly faster than the rest of the economy and I think that will continue. But decarbonizing the power sector only addresses part of the problem and we’re going to see a big transition across the rest of industry, agriculture and elsewhere that will generate a wide range of opportunities and stimulate the economy too. I’m not just talking about rolling out more renewables, but about integration – bringing together the generation and storage of energy, ensuring that we are managing demands and have the right infrastructure.

As for my area of photovoltaics, we’ve seen great ideas and technologies come out of the UK that are very likely going to be developed outside the UK because the manufacturing capacity isn’t here. Nevertheless, those ideas and innovations can still benefit the country through licensing, partial manufacturing and new technology.

One thing to remember about solar power is it’s distributed. You can have solar generation without being connected to the grid. That not only opens some markets for certain applications where you want to generate electricity locally, but it also provides a route to energy security through back-up generation, towards which solar power will be an important part.

Stephen Milburn: Having a strong green-technology manufacturing base is a huge opportunity for the UK. My company is based in South Wales, where we have lots of highly skilled people who used to work in traditional industries but now don’t have many places to go. Yes, there’s a fantastic semiconductor industry here, but when it comes to deploying green technology we cannot outsource that responsibility to other parts of the world.

Green tech needs to be deployed in the UK’s industrial heartlands… if we don’t nurture jobs and skills here there’s a real risk they will be gone forever

Stephen Milburn

Green tech needs to be deployed in the UK’s industrial heartlands to take advantage of the skills we already have, but which we are at risk of losing. In fact, if we don’t nurture those jobs and skills here there’s a real risk they will be gone forever. Having a strong green-technology manufacturing base is a huge opportunity for the UK.

What needs to happen so that these opportunities can be put into practice?

Stephen Milburn: Many science graduates leave university equipped with solid academic rigour and a great scientific understanding, but they often lack practical green-technology skills. This summer my company is therefore hoping to launch a climate apprenticeship programme, which will allow graduates to pick up those skills. We need to build green-tech skills in the real economy, in particular those that will deal with climate change.

Jenny Nelson: The UK must do more to support its own innovations. We need better regulations to avoid unnecessary bottlenecks. We need to invest in infrastructure like the grid. We should completely avoid subsidizing fossil fuels and instead divert any subsidies into alternative economies. Finally, we need to train and educate people, showing the public the potential of green technology so that they become part of the transition, for example by generating their own electricity.

David Cole: We need to integrate our policies on industry, energy, land use and AI so that we can invest in them all as growth areas. In particular, I’d like to see a long-term nuclear programme in which we build a fleet of new reactors all of the same design, which will drive down costs by letting us replicate a particular technology. It’s also vital that we get a high proportion of UK content and technology into these reactors, which will lead to a virtuous circle, with money coming back into the economy that we can re-invest in industrial and academic partnerships.

Emily Nurse: What’s vital is consistency in policies; we need certainty. In the UK, we are fortunate to have world-leading climate legislation in the form of the 2008 Climate Change Act, which does not just make it a legal requirement to reach net zero by 2050 but also gives us targets along the way. It means we know what we need to do in both the medium- and long-term, which gives certainty to investors, businesses, innovators and consumers.

What’s really important is communication – supporting communities through the transition and making sure they realize the benefits

Emily Nurse

So the first thing we need to do is keep the Climate Change Act. Then, of course, we’ve got to address barriers to delivery, including having the right incentives to electrify the economy. And what’s really important is communication – supporting communities through the transition and making sure they realize the benefits, not just in terms of reducing carbon production but of having cleaner, better and more efficient technologies too.

John Browne: First, we must never stop investing in people who can discover things and translate them into real commercial products. Second, we need to understand how to scale things, which means focusing on the winners and getting rid of things that are “nice to have” but aren’t going anywhere. That’s not easy because you have to push people to say, “You’ve done great work, but you’ll have to stop”.

What’s more, to scale new technology, people have to learn what it takes. When I’m in the US, I often speak to chief executives who can explain their technology to the financier who’s supporting it, whereas here in the UK that often doesn’t happen.

Third, we need to maintain confidence in what we’re doing. I often talk to people who think that it’ll be really expensive to get to net zero, but in fact estimates suggest that each household would only have to spend an average of about £150 a year to get there. So it’ll be less than the cost of a TV licence to get to net zero.

Of course the investment needed will be “lumpy” – it’s not as simple as just levying a fee – but the point about governments is that they can smooth things out. That is what they have done in the past and it’s what they should continue to do.

• For more information about the IOP’s work on the green economy, click here. You can also keep up to date with the all latest research in the field through IOP Publishing’s series of open-access Environmental Research Journals at this link.

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Photonic glasses containing gold-cored, silica-shelled nanoparticles can produce high-purity colours across the visible spectrum. Crucially, the colours are independent of viewing angle. Developed by researchers in Korea, their design avoids the short-wavelength scattering that has prevented the attainment of a true red – and blurred other colours – in previous photonic glasses.

Synthetic materials are usually coloured using pigments, such as those found in dyes or paints. A pigment has a chemical composition that causes it to reflect light at certain wavelengths and absorb light at other wavelengths. Nature, however, makes widespread use of structural colour, whereby the physical structure of a material dictates which wavelengths are reflected and which are absorbed. A familiar example is iridescence, which is responsible for rainbow-like colours on some plants and animals.

Creating colour using structure rather than chemistry has several advantages. One is that there are no chemical chromophores to be bleached by sunlight, so the colour tends to be more durable. Another benefit is that there is no dye to leach if the material comes into contact with water or another solvent.

While structural colour can be created using traditional photonic crystals, these can be tricky to produce controllably. Moreover, a surface that relies on interference effects is inevitably iridescent – which means that its colour changes with the viewing angle.

Short-range order

One solution is colloidal photonic glasses, which are not physically textured but have particles such as silica or polymers dispersed throughout them with short-range order. These can be produced simply by solution processing, and their colour does not vary with viewing angle. The principal problem with these glasses is the attainment of colour purity – especially in the red. The challenge is that the glasses scatter light more effectively at shorter (bluer) wavelengths owing to Rayleigh scattering. This effect makes the sky appear blue and adds unwanted blue light to structural colour.

In the new work, nanophotonics expert Seungwoo Lee of Korea University in Seoul and colleagues synthesized 230 nm core–shell nanoparticles in which silica surrounds a 20 nm gold cluster. This has a plasmonic resonance that absorbs shorter wavelengths. The researchers then dispersed the nanoparticles in ethoxylated trimethylolpropane triacrylate. This is a photocurable resin that has a very similar refractive index as the nanoparticles. The resin was applied to surfaces by painting or solution deposition and then cured under ultraviolet light.

The resulting photonic glass scatters red light randomly, while absorbing shorter wavelengths. Lee stresses that this is different from a traditional paint. “The reflected colour is determined by particle size, spacing, refractive-index contrast, and the degree of structural order, rather than by a molecular chromophore alone,” he says. When the researchers reduced the size of the nanoparticle shells, first to 180 nm and then to 160 nm, they found that they packed more closely together, producing first green and then deep blue colours.

The explanation for the blue scattering is more subtle than for the red: “The gold core is not needed to ‘make’ blue in the same way that a blue dye would,” explains Lee. “However, the gold core can still improve perceived colour purity by reducing broadband diffuse scattering and nonresonant background light.” explains Lee “Without this suppression, silica-only photonic glasses tend to look milky or whitish because many wavelengths are scattered together.”

Durable coatings

The researchers are now exploring several possible extensions of their research. They believe that the work could provide easily applied coatings that are durable as the light scattering comes from within the material structure rather from than a surface pigment.

They also believe it could have anti-counterfeiting properties: “In a normal ink or paint, its colour mainly originates from chemical pigments or dyes,” says Lee; “Our material produces a nanoscale structural signature: a specific reflectance spectrum, bandwidth, angular response, and microstructural arrangement determined by the particle diameter, core–shell geometry, refractive-index matching, volume fraction, and assembly pathway. This gives several possible authentication handles.”

Lee believes that it should be possible to reduce the cost of the material using a metal that is cheaper than gold. However, the precious metal is only 0.022% of the film by weight, so the technology may already be economically viable.

The film is described in Proceedings of the National Academy of Sciences.

“I think it’s really neat,” says materials scientist Aaswath Raman of the University of California, Los Angeles. “The concept of structural colour has been around for a really long time but to me it’s, like, the last steps before we see it out it the real world.”

He says the largest problems he foresees are the simple economics of competing with industrially-optimized paint industry – even if the technology is, in principle, superior. Nevertheless, he says, “of the technologies we see in research this is likely quite a good candidate for commercialization”. The next step, he says, is to actually find a “first use” application – he suspects the aerospace industry, which values ultralight, durable coatings, could be a candidate.

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In today’s technologies, mechanical mechanisms generally provide the brawn while electronics supplies the brains. This is partly because it is challenging to write information into mechanical memories without resetting each bit individually. However, that could change as researchers led by Pedro Reis at École Polytechnique Fédérale de Lausanne in Switzerland and Martin van Hecke at AMOLF in the Netherlands have now found a practical means of writing mechanical bits. Their technique, which they describe in Science Advances, uses structures that resemble children’s slap bracelets placed on a rotating turntable. While they acknowledge it is unlikely to replace electronic memories, they argue that it could have specialist applications and might produce insights that translate into electronic innovations.

“The framework we propose could be very useful, for example, in the domain of physical intelligence, where you provide software with capabilities that don’t require essentially a brain or an electronic control system to do individual tasks,” Reis says.

Mechanics for memory

Reis and van Hecke’s interest in mechanical memory stems from their research on metamaterials, which are materials that are defined not just by their composition, but also by the structures within them. Mechanical systems offer a tangible means of getting to grips with the complex behaviour of these metamaterials. “Often, all sorts of things that we do rely on nonlinear responses,” van Hecke notes, adding that such responses are much easier to study in mechanical systems than in optical devices.

A metamaterial made up of an array of switchable mechanical elements could function as a form of mechanical memory. However, to be practical, it needs to be possible to flip the states of individual mechanical bits using global controls, as opposed to addressing them individually. Otherwise, writing data will be very fiddly.

A solution emerged from Reis’ interest in rotating platforms, which he describes as “a very versatile way of loading mechanical systems”. While the pair had been friends for more than two decades, they had been working independently until, during a visit, the penny dropped and they realized that placing the metamaterial array on a rotating platform could provide the control they needed.

Because the angular velocity of the platform sends its momentum outwards, each mechanical object experiences a force in the radial direction, known as the centrifugal force. If this angular velocity is not constant, the object will experience an additional force in the orthogonal azimuthal direction, known as the Euler force. “So you have a complex force and bi-directional field that is highly tuneable,” says Reis. “And this tuneability is what we realized is very powerful.”

A rotating array

To construct their array, the researchers used clamped beams with two stable mechanical states – a little like a slap bracelet can be coiled up or flat, except these beams could either curve to the right or to the left. To individually address different beams, they ensured that each beam was unique in its width, the angle it was clamped at, and so on, all of which affect how much force is needed for a beam to ping into the opposite state. By tuning the parameters of each clamped beam and the angular acceleration of the rotating platform, they could engineer the applied force to switch (or not switch) specific beams, thereby writing data into the array purely by rotating the platform.

Doing this accurately requires a level of precision in acceleration control that surpasses what standard lab motors can achieve. However, the researchers say they were able to team up with a local company that had designed high-spec rotating platforms for its high throughput silicon chip production process. By programming platforms with five tailored clamped beams and the right rotation functions, they showed they could write the letters of the alphabet in ASCII script.

“This is a significant advance because it points toward future smart devices and robots that can be reprogrammed remotely without complex wiring or electronics, using only carefully designed motion‑based signals driven by a sole dynamic driving strategy,” explains Damiano Pasini of McGill University, Canada, who studies systems for mechanical computing but was not involved with this work directly.

Reis says he is excited about the scalability of the approach and its potential in high throughput experiments. Meanwhile, van Hecke is looking into how the idea might transfer to other systems, such as applying engineered force functions to crumpling sheets of complex glasses. “It just opens up possibilities for both studies, really fundamental studies of complex systems, but also real applications where you use this dynamic idea,” he tells Physics World.

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High‑voltage transmission systems are a key part of power grids, transporting electricity from where it is generated to where it is used. Electricity is moved at high voltage and low current to reduce losses and improve efficiency. These systems are essential for grid stability, integrating renewable energy, and enabling long‑distance power transfer. There are two main high‑voltage direct current (HVDC) technologies: line‑commutated converters (LCC) and voltage‑source converters (VSC). LCCs are an older technology that use high‑power semiconductor switches called thyristors and are suited to very large power transfers. VSCs are a newer technology that use insulated‑gate bipolar transistors (IGBTs), allowing faster control of power flow, better stability, and more compact converter stations.

In this study, the researchers interviewed thirteen leading experts to understand which HVDC technology is likely to dominate in the future, how semiconductor devices may evolve, and what cost or supply issues might arise. The experts agreed that thyristors used in LCCs are a mature technology with limited room for improvement, and that demand for LCC systems is declining in North America and Europe, though they will remain important in regions requiring very high‑capacity transmission such as China and India. In contrast, IGBTs used in VSC systems are expected to continue improving, particularly in reliability, packaging, and voltage capability, reflecting the growing use of VSCs in Europe and North America. Some experts even suggested that VSC converter stations may now be comparable in cost to, or cheaper than, LCC stations, and that further improvements in IGBT cost and performance could reduce VSC system costs further.

There was debate about whether silicon‑carbide (SiC) MOSFETs could eventually replace IGBTs in VSC systems. While SiC devices offer advantages in high‑frequency applications, they currently cannot handle the very high currents required for HVDC, and challenges remain in packaging and long‑term reliability. Experts also noted that although global demand for power electronics is rising, this is unlikely to constrain HVDC development; instead, shortages of other components, particularly high‑voltage transformers, may pose greater risks. Overall, this research clarifies which power‑electronic technologies are poised to shape the next generation of HVDC systems and highlights why future grids are expected to rely increasingly on VSC converters and advanced semiconductor devices.

Do you want to learn more about this topic?

Application of reinforcement learning in planning and operation of new power system towards carbon peaking and neutrality Fangyuan Sun et al. (2023)

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For Keamogetswe Ramonaheng, physics was never just about equations – it was about clarity. “From a young age, I was attracted to mathematics and science as a way of understanding complex phenomena through a structured approach,” she says. “Physics was the area that spoke to me the most because it is the foundation for the fundamental principles that govern the natural world.”

Ramonaheng is head of medical physics and radiobiology at the Nuclear Medicine Research Infrastructure (NuMeRI) in Pretoria, South Africa, where she applies the principles of radiation science to treat cancer. NuMeRI, which opened in 2024, is the first research facility in Africa dedicated to nuclear medicine. It’s a joint venture between the Steve Biko Academic Hospital, the University of Pretoria, iThemba Laboratories for Accelerator-Based Sciences and the Nuclear Energy Corporation of South Africa.

Ramonaheng’s academic journey began at the University of the Free State (UFS), where she completed her undergraduate and honours studies before starting an internship at Universitas Academic Hospital in Bloemfontein. There she saw how a rigorous physics training can lead to tangible, clinical benefits. “The ability to comprehend and harness the interaction between radiation and matter in the human body demonstrated the power and relevance of scientific inquiry,” she recalls.

In many ways, nuclear medicine found me

Keamogetswe Ramonaheng

Thanks to a fellowship from the International Atomic Energy Agency (IAEA), Ramonaheng completed a clinical placement at Royal North Shore Hospital in Sydney, Australia. She later continued her postgraduate studies at UFS, becoming the first Black South African woman to earn a PhD in medical physics for nuclear medicine. “In many ways, nuclear medicine found me,” says Ramonaheng, who is grateful to the encouragement of various senior staff members who saw her potential and guided her into the field.

Multifaceted role

Following a spell as an independent medical physicist and manager at Universitas Academic Hospital and lecturer at UFS, Ramonaheng joined NuMeRI in 2024 and the University of Pretoria. Along with the team of scientists she leads, Ramonaheng oversees the safe and effective use of ionizing radiation at NuMeRI used to treat and diagnose disease in a safe and effective manner.

It’s a varied role, which stretches from providing patient-focused clinical services to carrying out applied research. “We integrate research with operations,” says Ramonaheng. “That requires careful planning and rigorous quality assurance, ensuring that innovation does not compromise safety.”

Among her duties, Ramonaheng carries out dosimetry calculations for innovative radiopharmaceuticals, works on new forms of quantitative imaging, and helps to develop novel radionuclide therapies, including using alpha particles to treat cancer. She also uses gamma-ray cameras equipped with highly sensitive cadmium-zinc-telluride detectors, which allow radiopharmaceuticals to be quantified and imaged more precisely.

Ramonaheng is particularly interested in “theranostics” – a form of “precision medicine” that combines therapy with diagnostics. It involves giving a patient a tumour-targeting molecule labelled with a radionuclide. This allows the tumour to be visualized using techniques such as positron emission tomography (PET) or single-photon emission computerized tomography (SPECT). The same molecule – or one similar to it – is then used to deliver a therapeutic radionuclide directly to the tumour.

Daily challenges

For Ramonaheng, a typical day is fast-paced. Mornings often begin with her overseeing radiation-safety protocols and ensuring that radiation imaging and counting equipment are working as well as possible, such that they meet quality assurance standards. Through the day, Ramonaheng also oversees all operational medical-physics activities and carries out her duties as chair of NuMeRI’s radiation protection committee.

As the day progresses, she might find herself reviewing clinical theranostics dosimetry workflows to carrying out patient-specific dose calculations or evaluating quantitative imaging metrics from SPECT/CT and PET/CT systems. Other tasks include reviewing research protocols for cancer theranostics, mentoring postgraduate students at the University of Pretoria, and examining clinical trials.

Innovation accelerates when silos are dismantled

Keamogetswe Ramonaheng

Ramonaheng works in a highly interdisciplinary environment, collaborating with radiographers, nurses, radiochemists, radiopharmacists, medical physicists and clinicians to address live issues in real time. “Innovation accelerates when silos are dismantled,” she says.

The work is not without its challenges. Funding for postgraduate training is a persistent concern. Clinical physics is also a highly specialized field, which means it can be hard to recruit people with the right skills, who might be drawn to better-paid industry jobs. In addition, NuMeRI is an operationally complex mix of advanced imaging systems, radiopharmaceuticals and clinical regulations, which requires good project-management and planning skills.

But Ramonaheng, who recently won two awards at the 8th Theranostics World Congress in Cape Town, feels the benefits outweigh the challenges. “It is very fulfilling to see the translation of research into clinical application,” she says. Just as gratifying, she adds, is watching her students move from their studies to publications and clinical applications. “You see the entire process of scientific advancement.”

A more promising future

Looking ahead, Ramonaheng envisages a growing use of artificial intelligence (AI) in her work. She also collaborates with national and international partners to automate workflows and enhance efficiency, precision and patient-centred care. Another ambition for Ramonaheng is to further strengthen NuMeRI as an Africa-wide hub for research, clinical service and training – a vision reinforced by the IAEA recently naming NuMeRI as one of 18 global “anchor centres” for its work in radiotherapy and medical imaging.

Ramonaheng believes medical physics will grow rapidly in Africa over the next 10 years, fuelled by an expansion of theranostics and precision medicine. Her hope is to guide this growth through mentorship and leadership, ensuring that Africa develops its own talent pool of medical physicists who can address the continent’s unique healthcare needs.

Africa suffers, for example, from limited access to advanced imaging and targeted therapies. Ramonaheng’s aim is to optimize personalized and precision medicine for cancer patients, ultimately improving treatment outcomes and quality of life. Eventually, she hopes, medical physics will be recognized as a profession across the continent. “We are building not only research outputs but human capital.”

Leadership is not only about the creation of paths, but the creation of paths where there were no paths previously.

Keamogetswe Ramonaheng

Being a pioneer in the field has required resilience on her part. “Competence must be coupled with confidence,” says Ramonaheng, who has had to learn the unwritten rules of a world dominated by men. As a mentor, her guiding principle is the African concept of motho ke motho ka batho babang – a person is a person only through others. “Leadership is not only about the creation of paths,” she says, “but the creation of paths where there were no paths previously.”

Her message to young physicists – particularly women and those from other underrepresented groups – is clear. “Medical physics is a dynamic and impactful field at the intersection of physics, medicine and technology,” she says. “ It allows you to see the direct translation of science to patients.” Medical physics requires resilience, curiosity and commitment, but for Ramonaheng its beauty is that equations don’t stay on paper – they become a tool for healing.

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With a PhD in nuclear physics, Paul Howarth has had a long career in the nuclear sector, working on the European Fusion Programme and at British Nuclear Fuels, as well as co-founding the Dalton Nuclear Institute at the University of Manchester. He was a non-executive board director of the National Physical Laboratory and served as chief executive officer of the National Nuclear Laboratory.

Howarth became president-elect of the Institute of Physics (IOP) in September 2025. In February he became IOP president after space physicist Michele Dougherty stepped aside from the role to avoid any conflicts of interest given her position as executive chair of the Science and Technology Facilities Council. Howarth is set to be IOP president until 2029. Physics World recently caught up with Howarth to find out more about his career and vision for physics.

What originally sparked your interest in physics?

I think it probably came from my father. He was a research chemist. We lived in Cheshire near the Jodrell Bank Observatory and its iconic Lovell Telescope. I was fascinated by that and it captivated my interest in astronomy and so I did a degree in physics and astrophysics at the University of Birmingham.

You stayed at Birmingham to do a PhD in nuclear fusion. What attracted you to that field?

It goes back to my interest in astronomy and the ability to use mathematics to describe the universe. Yet by the end of the degree, I was fascinated by nuclear fusion as an energy source and a sustainable means of clean energy for society. During my PhD, I got to work on the JET tokamak in Oxfordshire, which was wonderful. It was when JET was doing its first deuterium-tritium plasma shot, which was an exciting time.

After your PhD, you worked for British Nuclear Fuels. Why did you make that move and what appealed about the commercial side of physics?

In the 1990s there was quite a bit of uncertainty about the direction of nuclear fusion, but I’d always been fascinated by the huge monolith structures of nuclear power stations. So I didn’t hesitate when an opportunity arose to work at Sellafield – a huge site in north-west England with more than 200 nuclear facilities – on understanding the physics of plutonium.

You then served as chief executive officer of the UK’s National Nuclear Laboratory. How did that come about?

At British Nuclear Fuels I was working to build the case for the next generation of nuclear power plants. But in the early 2000s it was less clear that nuclear was going to be part of the UK’s energy policy. So British Nuclear Fuels was broken up into organizations such as the Nuclear Decommissioning Authority. But I was determined to continue to make the case for new nuclear build and ended up helping the UK government create a National Nuclear Laboratory to maintain sovereign nuclear capability, becoming chief executive officer in 2011.

What did that role involve?

We had contracts to support all aspects of the UK’s nuclear programme as well as build the case for future nuclear. We worked on the front end of the fuel cycle, on reactor technology, on future reactors, on legacy waste management and decommissioning. I had the responsibility for running about £2–3bn of critical nuclear real estate and infrastructure.

Many countries, not just the UK, are showing a renewed enthusiasm for nuclear – what do you attribute that to?

Yes, it’s a fascinating time for nuclear. I think things are heading now towards small modular reactors and advanced reactor systems. Larger nuclear plants are more efficient but it is possible to trade that off for smaller plants. This opens up the opportunity for others to potentially invest in nuclear. So we see, for example, individuals like Bill Gates and others who are looking at nuclear power.

That’s the challenge – to effectively support all aspects of physics. I don’t want to be in a position where we are pitching one area against another

Paul Howarth

Do you see parallels with the fusion industry and how that has grown in the past decade?

Absolutely. I think a very similar thing has happened. Of course, there’s still the engineering challenges associated with scaling up fusion but good progress is being made. And other players and entities, like Tokamak Energy and First Light Fusion, are looking at entering the market, which is great.

Having retired from the NNL in 2025, what drew you to the role of IOP president?

It was the opportunity to give something back to physics. Physics is such an important discipline that is needed across all aspects of society and through my time working in physics, I’ve seen the benefits that it brings.

What things excite you as you take up this position?

When we look across society, the impact that physics is having is massive – whether that is in data centres, artificial intelligence, net zero, medicine or even food supplies. One of the things I would like to achieve during my presidency is to qualify and quantify that impact. The role that physics can play is going to be fascinating and to be part of that journey is exciting.

What are your priorities as president?

One is to nudge the dial on getting physics recognized in society as a really valuable and important discipline. This includes making sure that schools are properly equipped and resourced for teaching physics as well as having more teachers with a physics background. This would then hopefully translate into more people studying the subject at A-level and degree level.

UK Research and Innovation (UKRI) recently announced funding changes that will see cuts to particle and nuclear physics. How do you see that impacting physics?

Yes, it’s a challenging time at the moment. We’ve been working hard to ensure that the impact is properly assessed and that we are doing what we can to champion and support some of these critical disciplines in physics. I can understand the direction of travel from UKRI, which is the importance that the investment underpins and supports economic growth. And there are some key critical disciplines such as quantum computing, autonomous system robotics and fusion that continue to be supported and where funding has actually increased. But what we are concerned about is the potential adverse or detrimental effects of a reprioritization that may move funding away from some critical areas in physics, such as particle physics, astronomy and nuclear physics. That is a concern because they are fundamentally important disciplines.

Could there be an impact on people wanting to go into these areas?

What I worry about is the negative impact on university physics departments that work in those areas. It’s also those areas of physics that really captivate people to study the subject. But there is a knock-on effect on other areas too because many people who study physics go into engineering, which is crucial for other industry sectors – whether it’s around detectors, data systems, data acquisition, electronics, power systems, automotive, aerospace, defence or nuclear energy. So I worry that the reprioritization is not properly assessing the impact and the benefit the subjects have.

How is the IOP tackling this issue?

We need to ensure that we fight the case for those areas of physics, because they are so important. We need to find a path that ensures we maintain these critical areas but also ensure that investment is being made to support economic growth as a whole.

How do you strike that balance between being vocal about the cuts, but also needing to support emerging areas of physics?

I think that’s the challenge – to effectively support all aspects of physics. I don’t want to be in a position where we are pitching one area against another. It’s the totality of the capability, and that’s all aspects of physics and the interrelationship between those disciplines too. We should celebrate where there is growth in new and exciting areas. But equally, we must protect those areas that are fundamental pillars of physics.

Are there any opportunities even in this difficult situation?

As we continue to engage government and other stakeholders on these funding changes, there is an opportunity to define physics’ impact as a benefit to society as well as big opportunities for science-driven growth arising from increased investment in key areas. I believe that a developed nation like the UK, which has a very good international standing, should continue to invest in all aspects of the discipline.

What other challenges lie ahead?

It is really important that we remain an inclusive discipline and we also need to get our heads around the impact of AI on physics. The IOP has already done some work with the community in this area with the Physics and AI Impact Pathfinder report, which highlighted the role of physics as both enabler and beneficiary of AI, and also explored the discipline-specific views physicists hold regarding AI in science and society. I am interested in us understanding more about what AI means for physics and being a physicist, how we embed AI in the training of physicists so physicists can use it and become better physicists. I would be keen for the IOP to carry out more work to understand the impact it’s clearly going to have.

How do you see the subject evolving over the coming decade?

I think that society is embracing what science and technology, and in particular physics, can do. We need to help ensure that the next generation of physicists are being appropriately trained to become good physicists. In fundamental physics, there are some fascinating things developing like bringing together cosmology and quantum physics, understanding quantum gravity, the nature of time and what’s happening down at the particle physics level. It feels as if something’s coming together. I’d love to be around when physics can finally pull all of that together and go “we’ve got it – the light bulb’s gone on”.

• You can listen to Paul Howarth in conversation with Michael Banks on the 14 May 2026 episode of the Physics World Weekly podcast

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Researchers in Japan have succeeded in measuring the temperature inside living cells with high precision using a new class of biocompatible quantum nanosensor – something that has been difficult to do until now even. If improved, the nanosensor could be used to characterize a wide range of biological phenomena and so help in disease diagnosis, they say.

Recent years have seen the advent of a new generation of nanoscale quantum sensors that can detect the tiny magnetic fields of biological systems. Some of these sensors rely on photons and others on electrons or spin defects – typically diamond specially engineered with nitrogen–vacancy (NV) defects. This material is made by removing two carbon atoms from the diamond lattice and replacing one with a nitrogen atom. The other “hole” is left empty, thereby creating a vacancy or defect. The spin state of the defect is influenced by the local magnetic field that can be “read out” from the way it fluoresces.

While a powerful tool, and biocompatible, this type of quantum sensor does suffer from certain limits. For one, it can be structurally inhomogeneous, which affects how it detects temperature and other physical or chemical parameters inside biological cells.

A more homogenous structure

Even though the new molecular quantum nanosensor (MoQN) works in the same way as these conventional devices, it does not suffer from this problem, explain Nobuhiro Yanai of the University of Tokyo and Hitoshi Ishiwata of the National Institutes for Quantum Science and Technology (QST), who led this research effort. This is because it has a more homogenous structure and does not contain any defects. Instead, it is made by embedding molecular spin qubits, in this case fabricated from pentacene, in nanocrystals of para-terphenyl. This design makes the structure uniform on a molecular scale and preserves the quantum coherence of the spin qubits. It is then coated with Pluronic F127, which is a biocompatible surfactant.

By detecting the spin direction of the “excited triplet state” of the pentacene qubits using a technique known as optically detected magnetic resonance (OMDR), the researchers can precisely determine the temperature of the qubits’ surroundings from the OMDR peak position. When they tested their method inside the cytoplasm of cancer cells in vivo, they found that the intracellular temperature was consistently higher than the surrounding medium.

Yanai says he embarked on this study after reading about the work of Sam Bayliss’ group at the UK’s University of Glasgow, and Ashok Ajoy’s group at the University of California, Berkeley in the US on OMDR in pentacene-doped para-terphenyl crystals. He says he immediately got the idea that nanocrystals of this material could be used for quantum sensing inside cells. This was because his group had already developed such nanocrystals for a different purpose in previous research.

Ensuring biocompatibility

“I then spoke with Hitoshi Ishiwata, who is an expert in quantum sensing using NV centres,” he recalls. “While many molecular qubits have been developed to date, there had been no examples demonstrating their sensing ability within living cells.”

The project required materials science expertise, he tells Physics World, and in particular, finding out how to reduce the material to the nanoscale and ensuring it was biocompatible.

“We already knew that nanodiamonds are good quantum sensors for temperature measurements, but I had noticed a practical limitation: their ODMR spectra often vary significantly from particle to particle,” he says. “This spectral dispersion can introduce errors, especially when trying to perform precise measurements at the single-particle level.”

Replacing hydrogen with deuterium

The researchers thought they had overcome this problem during the first run of their experiments because they found that different particles showed identical OMDR spectra. However, their joy quickly waned when they observed that the spectra were still broadened by hyperfine interactions between the pentacene-doped para-terphenyl molecules’ electron spins and hydrogen nuclear spins.

To improve the spectral resolution, Ishiwata says he suggested chemically modifying the molecule by replacing the hydrogen in it with deuterium. And the technique worked: “the hyperfine broadening was strongly suppressed, allowing us to determine the OMDR spectra much more precisely.”

These findings, which are detailed in Science Advances, show that MoQNs are a chemically versatile platform for quantum sensing in living cells and that they can operate directly inside them while maintaining the precision needed for absolute thermometry, he says. Their appeal also lies in in the fact that their structures can be easily modified.

It will not all be plain sailing, however, adds Yanai. MoQNs cannot yet target specific organelles within cells, so endowing them with this targeting capability is an important future challenge. “What is more, their size has been limited to around 200 nm so far, so creating smaller MoQN particles will be crucial,” he says.

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Fancy some more? Check out our puzzles page.

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News that large language models (LLM) have made major advances in solving Erdős problems – a set of problems formulated by the renowned 20th-century mathematician Paul Erdős – has created an amalgamation of uproar and interest among mathematicians. The past month alone has seen two significant LLM-generated solutions. The first relates to prime sets, a generalization of prime numbers, and was solved after Liam Price, an amateur mathematician from the US, fed the problem statement into GPT-5.4 Pro without other information. The second came last week when the company behind ChatGPT, OpenAI, announced that it had used artificial intelligence to disprove Erdős’ planar unit distance conjecture.

LLMs have solved Erdős problems before, but the one Price chose wasn’t just any Erdős problem. It was one that human mathematicians had worked on for 60 years without success. The nature of the solution was also unusual. While previous LLM solutions to Erdős problems used standard techniques, this one took an entirely different approach. Rather than starting from Erdős’ original probability-theory-based framing of the problem, as human mathematicians had, the LLM found an alternative route – one that led naturally, in less than a page, to a correct proof.

“Paul Erdős had a concept of ‘Proofs from The Book’, meaning that the argument is so compact and elegant that this is the proof God would’ve written down in ‘The Book’,” Jared Lichtman, a mathematician at Stanford University in the US, wrote on the social media site X after the proof was announced. “After reading the GPT5.4 proof of Erdős #1196, I would say this is a Book Proof of the result.”

The planar unit distance conjecture, meanwhile, concerns a deceptively simple question: if you have n points in a plane, how many pairs of points can be exactly one distance unit apart? Erdős thought the limit was n^{1+C/log log(n)} where C is a positive constant, but OpenAI’s model identified a higher bound. What’s more, the company claims it did so not by rehashing prior work, but by “bring[ing] unexpected, sophisticated ideas from algebraic number theory to bear on an elementary geometric question”.

Some members of the mathematics community have greeted these proofs, and the advent of AI in mathematics in general, with enthusiasm. OpenAI’s announcement quotes Arul Shankar, a number theorist at the University of Toronto, Canada, as saying that the new proof “demonstrates that current AI models go beyond just helpers to human mathematicians – they are capable of having original ingenious ideas, and then carrying them out to fruition”.

Others, however, are more cautious. David Bessis, a mathematician-turned-science writer who previously worked on algebra, geometry and topology, claims that even such apparent successes stem from a misconception of mathematics as a logically direct process of churning out theorems, given some rules. Writing in his Substack newsletter, Bessis argues that the method used to verify AI-generated proofs, which involves a computer program called Lean, may reduce the benefit the mathematics community gains from proofs. Notably, proofs that are verifiable in Lean are not always parse-able by humans, which detracts from (and in certain cases removes) the insights researchers typically get from new proofs.

How AI is being used in mathematics…

To evaluate the merits of these arguments, it’s useful to understand how AI is currently used within mathematics research. The first strategy is the one Price used to solve Erdős #1196: directly prompting an LLM. “Large language models have proven their worth at literature search: finding similar instances of a problem, or a proof, in past literature,” notes François Charton, an AI engineer at the California-based start-up AxiomMath, which is using AI to accelerate mathematics research.

The second strategy is to use AI models trained on other types of data. According to Charton, these models are especially good at spotting “weak signals and correlations” and thereby uncovering patterns in data that might be too laborious or convoluted for humans to identify.

Both methods have shown promise for generating new results, but they are not universal – at least, not yet. “It [AI] seems to do a lot better at certain types of maths than others,” says Thomas Bloom, a mathematician at the University of Manchester, UK, who maintains a webpage that tracks solutions to Erdős problems. In particular, Bloom says that to the best of his knowledge, AI “hasn’t done anything interesting in category theory” – a field whose reputation for abstraction is only matched by its track record of bridging supposedly distinct areas of mathematics.

Another challenge is that with AI systems churning out new proofs at scale, there are simply not enough people with the skills needed to check them. A process called autoformalization could solve this problem by turning human proofs into what Bessis calls “bulletproof, machine-verifiable logical derivations” expressed in Lean or other specialized languages. At that point, AI-generated proofs could be checked automatically. The question is, what knowledge will humans gain in the process?

For doubters like Bessis, who refers to autoformalization (at least as practiced by certain firms) as “AI slop”, the answer is very little. But within the broader mathematics community, there is considerable interest in autoformalization, if done correctly. “I see autoformalization as the bridge in both directions, as important as proving itself,” Charton argues. “We can use Lean to translate between these two languages so that a Lean proof can be reverse-translated into a sketch, lemmas or natural language a human mathematician can engage with. That bidirectional translation preserves and extends mathematical knowledge at scale.”

…and how it isn’t

In the 18th century, when Leonhard Euler began arranging the logical thought processes of mathematics into theorems, definitions and proofs, mathematicians were primarily interested in solving problems with underpinnings in the physical world: questions of volume and distance, and, more generally, geometry and counting. Since then, though, mathematics has become a discipline that is at least as concerned with coming up with interesting problems as it is with solving them.

Two aspects of this change seem relevant to debates over AI’s utility. The first is that posing problems requires a broader skillset than solving them. The second is that solving posed problems sometimes requires mathematicians to invent new structures, tools or objects. Fermat’s Last Theorem, which posits that there are no three positive integers a, b, and c that satisfy the equation aⁿ + bⁿ = cⁿ for any integer value of n greater than 2, is a good example. At face value, this nearly 400-year-old theorem seems simple. However, proving it was the life’s work of a modern mathematician, Andrew Wiles, who won the Abel Prize in 2016 for developing the numerous new tools required, as well as for the proof itself.

Coming up with such tools – or indeed whole new frameworks – is a challenging and hugely creative endeavour. There are no rules as to the kinds of objects you are allowed to create, and unlike a proof (which is either correct or incorrect), there is no finality, either. If the new framework is a good one, it will crop up frequently and naturally in various branches of mathematics, and other mathematicians will incorporate it into their own work. If it isn’t, they won’t.

Currently, not even AI enthusiasts like Charton think machines are capable of such leaps. “Theory building is completely out of reach right now,” he tells Physics World. “Models, especially generative models, can provide a mathematician with interesting examples, or discover surprising relations that may bring a theoretical breakthrough, but the breakthrough still depends on the mathematician. I believe this will remain the case for some time.”

A new tool for scientists and mathematicians alike

In many areas of science, AI works in a way that is entirely distinct from human thinking. In physics, for example, machine learning algorithms are trained to analyse large amounts of data, find patterns and use them to infer underlying laws. This strategy could advance our understanding of some of the most fundamental questions in physics, but it is very different from how a human scientist would do it, and therefore perhaps more likely to be seen as a welcome new tool.

On the theorem-proving side of mathematics, the distinction between methods a human might use and those an algorithm might use is more blurred. Yet in some ways, Bloom thinks incorporating AI into mathematics could bring the field closer to other sciences. In particle physics, for example, “you don’t go in and take these individual recordings [of data]. It’s all automated,” he tells Physics World. “Until now, there has been no equivalent for maths. It takes time and attention to prove theorems, and maybe this had been a bottleneck.”

AxiomMath’s Charton agrees. “Every new math tool in history has automated something that used to be the work of a human mathematician – from the abacus all the way to symbolic algebra,” he says. “With each new tool, the role of the mathematician evolved rather than disappeared. Tasks got automated, and problems that felt impossible became trivial – but mathematicians just keep moving up the stack to the next set of questions. I see AI as the latest shift rather than a categorical break from history.”

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Data are at the core of science, but traditional journal articles normally deliver a distillation of the raw data gathered by the authors. While the movement towards open access to data is widely supported by researchers and funding agencies, a 2024 study by IOP Publishing revealed that many scientists still encounter a wide range of practical, ethical and technical barriers when it comes to sharing their data.

As a result, the publisher has launched a free online course that aims to give early-career researchers the practical skills and confidence they need to share and manage research data effectively.

To talk about the course and IOP Publishing’s open data policy I am joined by Laura Feetham-Walker, who is head of publishing strategy and performance at IOP Publishing.

IOP Publishing is a wholly owned subsidiary of the Institute of Physics and it publishes Physics World.

• You can register for the free course here: “Open Data Excellence“

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John Hill has become director of the Brookhaven National Laboratory in Long Island, New York, after serving as interim lab director since September. Hill will now oversee Brookhaven’s 3000-strong team of scientists, engineers and technicians as well as manage the lab’s annual $900m budget.

Brookhaven opened in 1947 as one of the first three US national labs, the others being Argonne and Oak Ridge. Brookhaven carries out a wide range of research in the physical, biomedical and environmental sciences and is home to seven Nobel-prize-winning discoveries.

Brookhaven operated the Relativistic Heavy Ion Collider (RHIC) until it shut down in February. RHIC collided heavy nuclei such as gold and copper to produce a quark-gluon plasma – a state of matter thought to have been present in the very early universe.

In 2020, Brookhaven was chosen to host the next-generation Electron-Ion Collider (EIC). Costing about $2bn, the EIC will smash together electrons and protons to probe the strong nuclear force and the role of gluons in nucleons and nuclei.

Building the EIC involves revamping the RHIC accelerator as well as adding an electron ring and other components with the first experiments starting the 2030s.

As well as RHIC and the EIC, Brookhaven is also home to other big-science projects including the National Synchrotron Light Source II, which opened in 2015 at a cost of $912m.

A Brookhaven career

With a PhD in physics from the Massachusetts Institute of Technology, Hill joined Brookhaven as a postdoc in 1992 before leading the lab’s X-ray scattering group from 2001 to 2013.

He then became deputy associate laboratory director for energy and photon sciences until becoming the lab’s deputy director for science and technology from 2023 to 2025.

In September 2025 he became interim director following the resignation of the theoretical physicist JoAnne Hewitt.

In the role, Hill will also become president of Brookhaven Science Associates – a partnership between Stony Brook University and the science and tech firm Battelle – that manage and operate Brookhaven on behalf of the US Department of Energy.

Hill notes that he is “very excited” to lead the lab in the coming years. “Brookhaven is entering a defining decade, and I’m honoured to take on this role at this time,” he says. “The vision we have for our future is a powerful one, including delivering the nation’s next particle collider and advancing science across a range of critical areas.”

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Pollinating insects form a vital part of any ecosystem, enabling the biodiversity that we see on Earth today. However, biodiversity is in rapid decline around the world, and monitoring insect species is a difficult task that often requires some insects to be killed. To support the conservation of biodiversity, which is critical to ensure the sustainability of human civilization, more robust monitoring is required. In a study published in PNAS Nexus, researchers have developed a new method to identify and classify individual insects, based on radar imaging and machine learning.

Radar has long been used to study migrating insects that fly at high altitudes and in large numbers, but such systems typically perform wide-area, long-range monitoring. However, thanks to a combination of millimetre-wave radar and machine learning, narrow focused identification is now possible, by detecting changes in the radar reflection of insects caused by the flapping of their wings.

“Having a background in antenna engineering, there was always the question of whether this technology can be used to address some of the environmental challenges that we’re facing,” says co-lead author Adam Narbudowicz from the Technical University of Denmark. “Some five or six years ago, we started talking with [co-author] Ian [Donohue] about those possibilities, and eventually the idea of micro-Doppler emerged, which seemed feasible from an engineering point of view and could provide some useful data on biodiversity.”

The approach taken in this study doesn’t focus on morphological features of the insects, as these are difficult to detect with radar. Instead, it uses the harmonic patterns generated by the micro-Doppler effect of an insect beating its wings as a detection strategy. Millimetre-wave radar can provide insight into biomechanical characteristics not visible with cameras, and these characteristics are encoded in the harmonic patterns of the wingbeat.

The team used machine learning to improve the accuracy of the identification and incorporated a SHAP (SHapley Additive exPlanations) analysis – an explainable AI tool that interprets and explains key outputs and prioritizes key features – to identify which signal features are the most critical for differentiating insect species. The SHAP analysed each insect across the full spectrum of micro-Doppler harmonics, extracting key features including fundamental wingbeat frequency, energy distributions, cepstral coefficients (sound signals) and how quickly an insect’s wing movement change. These data were then used to train the machine learning model.

The actual process of obtaining this data from the insects involved capturing insects at the Trinity College Dublin campus and placing them in a plastic box on top of a millimetre-wave antenna that recorded their radar signatures. The researchers then released the insects back into the wild. After data capture, the relevant micro-Doppler features were extracted from the data for model training.

The model allowed non-invasive monitoring of different insects and could distinguish between bees and wasps with 96% accuracy. The model also classified five key pollinating insect species – red-tailed bumblebee, buff-tailed bumblebee, moss carder bumblebee, western honeybee and common wasp – with an accuracy of 85%.

“I think the most impressive thing is that we can detect and classify them with such an accuracy. From a biological point of view, it’s impressive how different species beat their wings in different manner, and from an engineering point of view it’s fascinating how different wingbeats affect harmonics of radar micro-Doppler reflections,” says Narbudowicz. “Those differences are of course impossible to see just by looking at spectrograms, but it appears that a sufficiently trained machine learning algorithm can see them.”

Narbudowicz points out that the current study used precise lab-grade transceivers and a relatively controlled set-up, and that the natural next step is to move this technology to outdoor field deployment. “This requires a number of steps,” he explains. “Firstly, the device needs to be miniaturized, and battery operated; the transceiver will be less accurate than the one used in the lab, but a big problem is the ground truth verification, since in the field it can be difficult to verify exactly which species flew over the sensor.”

Despite the greater challenge with deploying the technology in the field today, the researchers suggest that this radar reflection approach could be utilized in the future in a fly-through device, which would make it much easier and cheaper to achieve non-lethal monitoring of insect biodiversity in different environments.

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Colliding oxygen nuclei could briefly recreate one of the most extreme states of matter in the universe – according to evidence gathered by physicists working on the CMS Collaboration at the Large Hadron Collider at CERN. Their analysis suggests that when smashed together, even relatively small atomic nuclei can produce a tiny droplet of quark–gluon plasma (QGP). This is a superhot “soup” of elementary particles that is believed to have filled the universe just after the Big Bang.

Under normal conditions, quarks – the particles that make up protons and neutrons – are tightly bound together by gluons, which carry the strong nuclear force. But at extremely high temperatures, matter changes into a radically different form in which quarks and gluons move freely in a dense fluid-like state called a QGP.

Scientists believe the entire universe existed in this form for a tiny fraction of a second after the Big Bang. To recreate it here on Earth, physicists smash atomic nuclei together at nearly the speed of light.

One of the main ways researchers study this strange state of matter is by observing the fast-moving particle sprays created during the collision. In the absence of a QGP these energetic particles would travel outward freely. But if they pass through QGP, they lose energy, somewhat like a bullet slowing down in water. Physicists call this effect jet quenching.

“Jet quenching is one of the main tools we use to study the QGP,” explains Jiangyong Jia of Stony Brook University in the US, who was not involved in the CMS study. “When a high-energy collision produces a QGP droplet, energetic quarks and gluons created in the same collision have to travel through it, and they lose energy along the way.”

For many years, this energy-loss effect had only been clearly observed in collisions involving very heavy nuclei such as lead or gold. Lower mass systems, including collisions between protons and heavier nuclei, showed hints of unusual behaviour but no convincing evidence that particle jets were being slowed down.

A clear signal

The new CMS study examined collisions between oxygen nuclei, which are much smaller than lead nuclei. Oxygen contains just 16 protons and neutrons, compared with 208 in lead. This allowed researchers to investigate how small a droplet of QGP can become while still affecting energetic particles passing through it.

The collisions were performed in 2025 at an energy of about 5 TeV – the highest energy ever for oxygen ions. The CMS Collaboration measured how many high-energy particles emerged from the collisions. This was compared to simpler proton–proton collisions, which are not expected to result in jet quenching.

The physicists found a clear reduction in the number of energetic particles produced. At some energies, the suppression reached about 30%, far beyond what could be explained by random statistical fluctuations. The pattern looked remarkably similar to what researchers had previously observed in much larger lead–ion collisions, although the effect was weaker overall.

“Oxygen-16 has only 16 nucleons compared to 208 in lead, but it appears to produce a medium that absorbs jet energy in a qualitatively similar way to much heavier systems,” Jia explains. “The shape of the suppression curve in oxygen–oxygen collisions resembles what is seen in lead–lead, which suggests the underlying physics is the same.”

Understanding fireballs

The team compared its measurements with several theoretical models. Models that included energy loss caused by QGP generally matched the data better than models without it. Still, some uncertainty remains. Part of the observed effect may come not from a QGP itself, but from differences in how quarks and gluons are distributed inside oxygen nuclei before the collision even occurs.

“The main limitation right now is the nuclear parton distribution functions,” Jia says. These describe how quarks and gluons are arranged inside atomic nuclei. According to Jia, uncertainties in these distributions “can account for roughly half of the observed suppression on their own”.

Future experiments involving proton–oxygen collisions are expected to help clarify the picture. The findings may also reshape how physicists think about the minimum size needed to create QGP.

“It shows that QGP formation is not limited to heavy nuclei,” Jia says. “It can occur in collisions of nuclei as light as oxygen.”

Researchers now hope to compare oxygen with other light nuclei such as neon to understand how the properties of QGP change as the colliding systems become larger or smaller. The work could eventually help physicists build a more complete picture of how ordinary matter behaved in the universe’s earliest moments – and how the strong nuclear force operates under the most extreme conditions known in nature.

The research is described in Physical Review Letters.

The post Tiny droplets of primordial soup appear in oxygen collisions appeared first on Physics World.

Displayed in a sealed case at the National Archives Museum in Washington DC, the US Declaration of Independence is – alongside the Constitution, the Emancipation Proclamation and the Gettysburg Address – one of America’s most sacred documents. Just a single sheet of parchment, it was signed on 4 July 1776 by 56 representatives of 13 colonies, declaring themselves free of British rule. Even though years of fighting followed and Britain did not officially recognize the colonies’ independence until 1783, America dates its birth to that signing.

For many American citizens, the Declaration of Independence is greatly revered. I remember my grandfather had a copy mounted in the entryway to his home, and when I was 10 years old offered me $1 if I memorized it. I had no trouble with the start, for the document’s first sentence is arresting. “When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another”, decency requires that “they should declare the causes which impel them to the separation”.

The second sentence is equally exhilarating and unforgettable: “We hold these truths to be self-evident, that all men are created equal…”.  I didn’t discover until years later that this evidently didn’t include women, slaves, or the people referred to as “merciless Indian Savages”. Four truths later, the signatories zoomed in. When a government destroys “life, liberty and the pursuit of happiness” it is the “Right of the People to alter or abolish it”.

King George III was doing just that, they claimed, and the signatories followed with a laundry list of appalling grievances that amounted to tyranny. These included: obstructing justice, bending judges to his will, sending agents to harass and murder people, giving amnesty to those agents, transporting people overseas, cutting off trade with the rest of the world, making the military responsive to himself alone, and on and on.

Current US President Donald Trump claims that the Declaration of Independence led to “the greatest political journey in human history”. The document, he adds, set an example for the world. “The Story of America Makes Everyone Free,” he writes on an official website that has been counting down the days, hours, minutes and seconds to the 250th anniversary of the signing.

Destroyers of Earth

The enormous attention that the US administration is paying to this anniversary has made me wonder, however, whether a government today could destroy life, liberty and the pursuit of happiness badly enough to make it necessary to alter or abolish it. The answer was staring me in the face. What if it destroyed science enough to make citizens vulnerable to natural threats?

I’ve therefore been trying to imagine a revised declaration. Among the self-evident truths, I think, is that human beings are endowed with the right to protection against nature, that the purpose of science is to understand nature and its threats, and that a sovereign’s duty is therefore to foster science and act appropriately on its findings. A no-brainer, right?

These truths are more important than ever in the 21st century, I envision the document saying. Until recently in human history, nature could be treated as an inert stage for human activity. But human activity can now interact with nature in a destructive way to threaten human life, liberty and the pursuit of happiness.

We experience such destruction in the degradation of the Earth’s atmosphere, in rising sea levels, in the spread of infectious diseases, in the increasing pollution of land, sea and air, and in coastal floods and water shortages. The current US administration, I’d continue, is not only doing nothing to prevent this destruction, but also actively campaigning against people who are fighting it and trying to make the world safer.

Human freedom and independence require developing science to understand and cope with nature’s threats. When science is ignored, nature rules.

The administration claims that stopping these attempts increases the freedom of US citizens. It does not, however, and instead enslaves us to nature. Human freedom and independence require developing science to understand and cope with nature’s threats. When science is ignored, nature rules.

Yet the current US sovereign, a wannabe King, has made unprecedented attacks on science. His ignorance, denials and repudiations have unleashed untold damage and destruction to the health, welfare and safety of citizens. His actions threaten not only our lives but human lives elsewhere. His actions even threaten the global conditions that make human life possible at all.

Our grievances

My revised declaration would follow with a long and easily verifiable list of modern-day grievances. These would include the fact that Trump has declared that threats whose existence is scientifically well-established are hoaxes, scams and have “no basis in fact”. He has prevented agencies from investigating these threats and from developing technologies to use against them.

He has fired people who study these threats and installed political appointees to oversee funding of research. Despite publicly denying and ridiculing findings about climate change and rising seas, he has admitted their truth when it comes to protecting his own golf course.

The US administration has also declared, contrary to scientific findings, that claims of outbreaks of disease have been “fabricated” and that vaccines do not work. It has cancelled grants to develop vaccines, attacked vaccine makers, revoked recommendations that children be vaccinated, fired experts in vaccines, and damaged the process of vaccine development.

The US administration has sought to gut or close the most important US science agencies. He has withdrawn the US from international agencies that track and address the most important threats to human life and health. He has invented false facts about nature and forced US agencies to agree with him. And he has damaged and extorted America’s top universities by trying to dictate their research, hiring, admissions, courses and curricula.

The critical point

My document would reach a rousing conclusion.

A people, it would say, are only truly free and independent when they and their offspring are able to live in a safe environment, not stalked by disease, and educated freely without government interference. A sovereign who ignores and damages science is unfit to be a ruler by exposing the people to the enslavement of nature. Citizens in a democracy have the right to a leader who does not enslave them to nature.

The final sentence of the document would be: “Let us take those rights back.”

Like the Declaration of Independence 250 years ago, my imagined one may seem revolutionary but only expresses what Thomas Jefferson, the author of the original, called “the common sense of the subject.”

The post What a modern-day US Declaration of Independence should say appeared first on Physics World.

A successful clean‑energy transition depends on understanding how to balance variable renewable power with the growing electricity demands of transport, heating, and industry. A key challenge is capturing how renewable energy sources like wind and solar fluctuate hour by hour, but this variability also creates new opportunities to align supply with increasingly flexible forms of demand, such as electric vehicles, heat pumps, and other electrified services. Alongside these short‑term dynamics, it is equally important to determine the long‑term infrastructure needed to support a fully decarbonised energy system.

In this research, two powerful models (REMIND and PyPSA‑Eur) are linked and allowed to exchange information repeatedly to determine both what infrastructure should be built and how it would operate each hour of the year. REMIND is a global energy and climate model that looks decades ahead, analysing investments, technology choices, and pathways to net‑zero. PyPSA‑Eur is a detailed model of the European electricity system that simulates real‑time grid behaviour. By combining a model that excels at long‑term planning with one that captures hourly power system dynamics, the researchers create a much more realistic tool for answering these complex questions. 

They then test this approach on a Germany case study under two conditions: one with demand‑side flexibility (where electricity use can shift to cheaper hours, such as smart‑charging electric vehicles) and one without flexibility. Their findings show that a fully renewable energy system is technically and economically achievable, that flexible systems perform far better than inflexible ones, and that even with flexibility, electricity prices can vary significantly between sectors, creating political challenges around fair pricing. Both scenarios of the German case study reach net-zero emissions by 2045.

This research gives policymakers a clearer way to design reliable, affordable, fully renewable energy systems by showing how to integrate renewables, manage electrification, use flexibility to reduce costs, understand sectoral price differences, and build markets. 

“Models used to inform climate policy have always faced a fundamental trade-off: they either capture the long-term perspective needed for investment decisions, or the hourly detail needed for power system planning, but not both. Our coupling of REMIND and PyPSA-Eur is a first step towards resolving this trade-off for an increasingly electric future energy system.” – Dr Adrian Odenweller, Potsdam Institute for Climate Impact Research

Do you want to learn more about this topic?

The role of grid-forming inverters in enabling high penetration of renewable energy in power systems: standards, ancillary services, current deployment, and future perspectives Ali Q Al-Shetwi et al. (2026)

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Earthquakes occur when tectonic plates rub against each other, become temporarily stuck, and then suddenly release accumulated stress as they slip. Although earthquakes have been studied for decades, the microscopic mechanics that cause faults to stick, slip, and generate friction are still not fully understood. 

In this research, scientists use a granite-on-granite system to investigate these processes. Granite is common in continental crust and mechanically similar to many fault rocks, making it a strong laboratory analogue. The researchers used three complementary approaches. First, they performed controlled experiments measuring friction, wear, and surface roughness as two granite surfaces slid past each other, including tests with water, different temperatures, and different sliding speeds. Second, they ran molecular dynamics simulations of a silica (amorphous SiO₂) tip sliding on quartz (crystalline SiO₂), the dominant mineral in granite, to observe how atomic bonds break, phases transform, heat builds up, and friction emerges. Third, they applied theoretical models of contact mechanics (how surfaces actually touch through tiny asperities) and flash heating (how much local heating occurs and whether it weakens the material). 

Traditionally, earthquake models assume that friction comes from mechanical processes such as asperity interlocking (high points locking together), plowing (hard grains digging into the opposite surface), and gouge grinding (crushed particles resisting motion). However, this study shows the opposite of what those models predict: more wear leads to less friction, and less wear leads to more friction. Instead of friction coming from grains digging or grinding, it arises from tiny asperities that plastically flatten, cold‑weld together, and resist sliding because their welded atomic bonds must be broken. This represents a major shift in how fault friction is understood. 

The study also finds that friction is largely insensitive to temperature, sliding speed, and hold time, suggesting that classic rate-state friction laws may not scale to real faults. The simulations identify three main energy dissipation mechanisms which are bond breaking, plastic deformation, and stress‑induced phase changes. This shows that flash heating at laboratory speeds is too small to weaken quartz, whereas earthquake level slip speeds would generate much stronger thermal weakening. They also reveal that certain quartz polymorphs can form purely from stress, meaning their presence in natural faults does not necessarily indicate high temperatures. 

Taken together, these results suggest that fault friction is dominated by adhesive bonding at asperities rather than mechanical grinding, and that tectonic motion may be governed more by creep‑slip than classic stick‑slip behaviour. 

Do you want to learn more about this topic?

The physics of earthquakes by Hiroo Kanamori and Emily E Brodsky (2004)

The post The hidden mechanics behind earthquakes appeared first on Physics World.

An absolutely maximally entangled (AME) state is one in which every possible division of a many-body system into two groups is as entangled as quantum mechanics allows. This makes AME states uniquely valuable as benchmarks for quantum theory and as resources for quantum technologies. Yet basic questions about their existence, structure and classification have remained unresolved, even after two decades of study.

In a new work, dedicated to Ryszard Horodecki, this field has been advanced in several important ways. First, the authors provided a comprehensive and up to date overview of known methods for constructing AME states, going beyond traditional approaches based on stabilizer and graph states. The authors showed how recent ideas from combinatorics, matrix and group theory generate entirely new families of highly entangled states that were previously unknown.

They also went on to study how entanglement behaves when particles are removed from an AME system. This reveals how robust these extreme states are to loss and noise, an essential consideration for real quantum technologies.

One highlight is a solution to the quantum version of Euler’s famous “36 officers” problem.  This puzzle asks whether 36 officers from six ranks and six regiments can be arranged in a 6 x 6 grid so that no row or column repeats a rank or regiment. Classical mathematics proves this is impossible.

The paper shows however, that quantum mechanics can bypass this restriction altogether. By using an absolutely maximally entangled quantum state, the researchers constructed a quantum version of the puzzle in which all constraints are satisfied simultaneously. The solution relies on superposition and quantum entanglement rather than fixed arrangements, illustrating how quantum theory enables outcomes forbidden in classical mathematics.

By mapping the limits of multipartite entanglement, this work connects abstract theory with practical goals such as quantum error correction, secure communication, and benchmarking future quantum computers.

The post Pushing many-body entanglement to its absolute limit appeared first on Physics World.

Celebrity gossip might break the Internet, but not in the way that quantum computers could. “The advent of quantum computers poses a critical threat, as they could break widely deployed encryption schemes,” warns Lily Chen, a cryptography expert from the US National Institute of Standards and Technology (NIST). Systems at risk include banking encryption, digital signatures, secure messaging, secure shell tunnelling, cryptocurrency and more.

Today’s quantum computers are still too small and error-prone to defeat gold-standard encryption. However, new results from Google Quantum AI and start-up Oratomic suggest that could change, with two widely used cryptographic systems – elliptic curve cryptography (ECC) and the Rivest-Shamir-Adleman (RSA) algorithm – potentially coming under threat sooner than many scientists predicted.

Space–time trade-off

At present, anyone who wants to access encrypted information needs a secret digital key. To obtain this key, an attacker must first solve a difficult mathematics problem. For example, breaking the RSA algorithm boils down to factoring a large number into its prime components. Breaking ECC involves finding a secret number that connects two points on an elliptic curve.

Classical computers might take billions of years to solve these problems. But if an attacker had access to a powerful enough quantum computer, they could solve the problems in mere minutes using an algorithm devised by Peter Shor in 1994.

Several years ago, experts estimated that cracking a typical RSA scheme with 2048-bit keys (RSA-2048) would require tens of millions of physical quantum bits (qubits), which are the building blocks of quantum computers. A year ago, this value dropped to a million. By February 2026 it was down to 100,000. The latest results from California-based Oratomic push the floor even lower, to 10,000 physical qubits. The largest neutral-atom qubit array – realized last year in the lab of Oratomic co-founder Manuel Endres – stands at 6100 qubits. This makes the benchmark of 10,000 feel alarmingly close, though Endres’ array hasn’t yet been used for computation.

There are, however, trade-offs. Quantum computers that use fewer qubits or more space-efficient hardware generally have longer computation times. Oratomic’s proposed 10,000-qubit platform would require three years to crack ECC with 256-bit keys (ECC-256) and 120 years to crack RSA-2048. The company’s predicted time-efficient alternative could solve ECC-256 in 10 days, but that would require 26,000 qubits. Solving RSA-2048 in 97 days would take 100,000 qubits.

Oratomic’s numbers have not yet been peer-reviewed, and outside experts say they depend on different assumptions about future hardware developments. “The space-efficient [architecture] is mostly based on assuming aspects that have been demonstrated to work individually in state-of-the-art academic labs,” explains Maria Violaris, a quantum physicist at Oxford Quantum Circuits, who was not involved in the research. “Meanwhile, the time-efficient one relies on more speculative assumptions that need future innovation.”

A second perspective

On the same day as the Oratomic team posted its findings on the arXiv preprint server, researchers at Google Quantum AI released a white paper with their own updated resource estimates. They report that a computer with 500,000 physical qubits made from superconducting circuits could solve ECC-256 in 18 minutes – and potentially even less (see box). Google’s current state-of-the-art processor, Willow, has 105 physical qubits. However, the researchers warn against assuming gradual and predictable progress because quantum computing developments are driven by overcoming scaling barriers rather than by steady increases in processor size.

The high number of physical qubits required for quantum computation comes from the need to detect and correct errors. Google Quantum AI’s estimate is based on a well-known error-correction method known as the surface code. In this approach, physical qubits are arranged in a rectangular grid and interact with their nearest neighbours. Quantum information is spread redundantly across this grid, allowing errors on one physical qubit to be found and fixed. The entire grid is considered one logical qubit, and the ratio of logical to physical qubits is called the encoding rate.

In the surface code, reducing error amounts to adding more physical qubits per logical qubit, and typical encoding rates range from a few hundred to a few thousand. In contrast, the Oratomic team based its estimates on a newer method of error correction called quantum Low-Density-Parity-Check (qLDPC), which reduces error more efficiently by making the physical qubits interact over large distances. Hengyun (Harry) Zhou, a physicist at the Massachusetts Institute of Technology in the US who was not involved in the research, explains that this longer-range connectivity can significantly increase the encoding rate. For qLDPC codes, a typical rate is around 1 to 10, but rates can now go as high as 1 to 2.

Because neutral atoms are highly reconfigurable, neutral atom platforms like those used by Oratomic (and other companies, including QuEra Computing, Infleqtion, Pasqal, planqc and Atom Computing) are naturally suited to the required long-range connectivity that qLDPC codes require. However, Zhou argues that it’s “not completely out of the question” that superconducting qubit platforms could use these codes too. “There is some additional cost that the lack of reconfigurability in those platforms currently leads to, but I would say if we’re thinking about a beyond-10-year timescale, it’s quite imaginable that things could also change for other platforms as well,” he says.

Responsible disclosure

Google Quantum AI’s white paper may represent a turning point in another respect. Rather than being open about their circuit designs, its authors hid them behind a “zero-knowledge proof”, which provided enough information to verify claims while hiding details that they say could provide bad actors with an “instruction manual”.

This is a relatively novel approach within the quantum computing community, which has thus far followed the conventional academic practice of publishing results with full transparency. A Google blog post expresses hope that “our approach to responsible disclosure can spur an important conversation among quantum computing researchers and the broader public”.

Certainly, it has already spurred a conversation among experts. “This is the first time I’ve ever seen a new mathematical result actually announced that way,” Scott Aaronson, a quantum physicist at the University of Texas at Austin, US, wrote on his blog. “I’m not sure how much it will actually help, as once other groups know that a smaller circuit exists, it might be only a short time until they’re able to find it as well.”

Zhou echoes this sentiment. “These are the kind of results that could potentially have a lot of general societal safety implications, so you want to make sure that they’re safeguarded responsibly,” he observes. “That being said, I think it is also possible that other people, now that they know what is possible, might come up with related constructions.”

What comes next?

In the long run, protecting against threats likely means migrating away from RSA and ECC and towards new mathematical problems that are difficult for both classical and quantum computers to solve. Google recently introduced 2029 as an internal deadline for migrating major system to so-called post-quantum cryptography (PQC), and many experts believe the migration ought to begin now.

“Migrating to PQC is a massive undertaking that won’t happen overnight. Starting migration today is a necessary risk management strategy,” urges Chen from NIST. She notes that NIST has been instrumental in guiding this migration, beginning with its 2016 call for cryptography experts to design and evaluate new algorithms for PQC, and culminating in its publication of the three most promising ones in 2024.

The Google Quantum AI researchers also outline recommendations to help cryptocurrency communities and policymakers prepare for the PQC era. And while urgency permeates their white paper, ongoing PQC efforts prompted them to end it on a positive note. “These trailblazing projects demonstrate that transition to post-quantum cryptography is realistic and instil hope that it will have been completed before the first [cryptographically relevant quantum computers] come online,” they write.

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The most precise calculation of the muon’s anomalous magnetic moment to date has put to rest the possibility of that property revealing new physics beyond the Standard Model – at least for now. The new result, from an international team of physicists, was obtained using a new method to calculate this anomaly that is based on lattice quantum chromodynamics (QCD).

In the Standard Model (SM) of particle physics, which is currently our best theory of the fundamental forces of nature (barring gravity), the muon is an elementary particle. It belongs to the same family (of quarks and leptons) as the electron, but is more than 200 times heavier. The muon interacts with other SM particles via two of the fundamental forces – electromagnetism and the weak force.

Quarks and leptons all possess a magnetic moment that comes from their intrinsic angular momentum, or spin, and quantum theory posits that this magnetic moment is related to the spin by the “g-factor”. This quantity was originally calculated to be equal to exactly two for both the electron and muon.

Experiments over the last 50 years have detected minute deviations from this number, however. This difference, of roughly 0.1 %, is known as the “anomalous g-factor”, a_µ = (g – 2)/2, and it comes from so-called radiative corrections – the continuous emission and re-absorption of short-lived “virtual particles” by electrons and muons.

Measuring such discrepancies is very important for physicists because the g-factor could point to the existence of other particles – both known and as-yet undiscovered – so hinting at physics beyond the SM. They can do this thanks to the muon. Since this particle is so heavy compared to the electron, the impact of virtual particles acting on it is significantly greater. This enhanced sensitivity means that measuring the muon g−2 is better for searching for new physics than the electron g−2.

Difficult measurements and calculations

The problem is that such calculations are not easy – all the more so because the muon’s magnetic moment also receives contributions from the strong force as well as the electromagnetic and weak interactions (even though the muon does not itself partake in strong interactions). These strong contributions come from the muon interacting with the photon, which in turn interacts with quarks that then themselves interact via the gluon — the mediator of the strong-force.

The strong force (which is responsible for binding quarks into protons, neutrons and other hadrons) is notoriously difficult to integrate into theoretical calculations, however, because it is so strong.

In the new work, the researchers overcame this problem using lattice QCD of the most uncertain theoretical contribution to the muon g−2 – the “leading-order hadronic vacuum polarization” (LO-HVP), which has been traditionally determined using experimental data. Lattice QCD, they explain, is a computational technique that simulates the strong force on supercomputers by dividing space-time into a fine grid or lattice of small cells. The equations of the strong interaction are then solved on this lattice.

To reach the level of precision required to calculate the muon g−2, the researchers improved on their previous lattice calculation using finer grids and also combined it with experimental data in the very long-distance interaction region. This hybrid approach dramatically reduced errors, so allowing for the most precise value of the muon magnetic moment ever.

“Our result together with the other contributions yields a prediction that combines three interactions (the electromagnetic, weak and strong forces), each of which require vastly different theoretical tools, into a single calculation that differs from the recent experimental measurement of a_μ by only 0.5 standard deviations,” says Kalman Szabo of Penn State University in the US, who is a lead researcher on the team. “This provides a notable validation of the Standard Model to 11 digits.”

The original goal in their latest work, he explains, was to have an unambiguous and ab initio pure theoretical work to calculate the magnetic moment of the muon. “When we started, there were very strong signs that there was a tension between experiment and theory in this quantity, which would mean the presence of a new interaction.”

No tension and no new interaction

“Confirming this tension would have been – with some bias from our side – the ‘fundamental discovery of the century’”, he says. “In the end, however, our study shows that there is no tension. Thus, we did not find the new interaction but proved that quantum theory holds with an unprecedented accuracy.”

The result does not mean that new physics has been ruled out, however, he adds. Future experiments and calculations will help clarify the picture, but for now, the Standard Model holds strong.

“We now have a beautiful proof of quantum field theory and this gives credibility to any further work based on this theory,” he tells Physics World. “The accuracy is astonishing, which gives hope to answer other questions related to the strong interaction with similar or even better accuracies.

“Indeed, other groups are now racing to try to validate (or refute) our result, something that can only beneficial for the advance of our field in general.”

The research is described in Nature.

The post Muon g−2 calculation sets precision record and backs the Standard Model appeared first on Physics World.

Two years ago, the ESTRO 2024 meeting in Glasgow dedicated a conference session to the discussion of upright radiotherapy. In particular, the speakers pondered whether this emerging technique – in which patients are treated sitting up rather than lying down – offers hope of increasing access to advanced radiotherapy, or whether it’s merely hype.

Things have moved on since then. Leo Cancer Care introduced its upright photon therapy system, Grace, and received commercial approval in the US and (just last week) Europe for its Marie upright positioning and CT system. Stanford Medicine recently unveiled the world’s first ultracompact proton therapy facility, pairing Mevion Medical Systems’ compact S250-FIT proton therapy system with the Marie platform. Meanwhile, the body of published research on the feasibility and patient experience of upright treatments continues to grow.

At this year’s ESTRO 2026 meeting in Stockholm, the theme was revisited by four experts in the field, who debated the motion that “Upright radiotherapy will be a mainstream and standard radiotherapy delivery option in 2035”.

The customary pre-debate vote revealed that just one quarter of the audience thought that photon-based upright radiotherapy would become mainstream, with the remainder believing that it would remain a niche technique. When it came to upright proton therapy, however, the vote was split roughly 50:50. So could the speakers persuade the attendees to change their minds?

Patient-centred care

The debate began with Tomas Kron from the Peter MacCallum Cancer Centre in Australia arguing the case for upright X-ray radiotherapy. He pointed out that upright positioning is not a new idea. “Historically, photons and upright have been around for a very long time. It has been, if not standard practice, widely used. But what role will it play in 2035?”

Kron described a clinical imaging trial underway at Peter Mac investigating upright cone-beam CT for planning lung cancer radiotherapy. The study showed that image quality was good enough for adaptive treatment planning, and that the lung was expanded and moved less in the upright position. Kron noted that patient setup and imaging was “really, really easy”, taking just a few minutes.

But what’s more important, he emphasized, is the patient experience. Patients treated while sitting up can maintain eye contact with the doctors throughout, they feel more involved and empowered, with one patient commenting: “My breathing was strong, I felt comfortable, the band around my chest was giving me a bear hug.”

“It’s really all about patient-centred care. Physical comfort and emotional wellbeing are top priorities,” Kron said. “Clearly, in an upright scenario this is much more likely to be the case.”

Upright radiotherapy offers many other unique features, including anatomical advantages and the ability to customize the chair, for example, for bariatric or paediatric patients. An upright treatment system is also more compact than a couch-based machine, requiring a smaller bunker. It could also be used as a mobile radiotherapy unit, said Kron – reducing the need for patient travel.

Kron’s team found that 80–90% of their patients could be treated just as well with upright radiotherapy as supine (lying down). “There are anatomical advantages with upright, there are patient preferences, there are economic benefits. What’s not to like,” he concluded.

The myth of mainstream

“Upright radiotherapy will not be mainstream and standard,” declared the second speaker, Livia Marrazzo from the University of Florence in Italy.

“Mainstream means widely adopted, used across the majority of radiotherapy centres, the default in clinical practice … and standard is even stronger, backed by clinical evidence, guideline-endorsed, reproducible and validated,” Marrazzo told the delegates. “It’s not ‘it works in some centres, is technically feasible, has early adopters, may have advantages for some patients’. But that is where we are with upright radiotherapy.”

From a practical standpoint, most of the roughly 16,000 radiotherapy systems worldwide are linac-based recumbent machines with a typical lifecycle of 10 to15 years. Many were recently replaced with supine systems optimized for intensity-modulated and image-guided radiotherapy. “The installed base is locked into supine geometry for another full cycle,” Marrazzo explained.

She refuted many of the advantages proposed by Kron. “We have limited clinical evidence supporting comfort advantages,” she said. “It may benefit specific patient groups and conditions, but this doesn’t mean mainstream.” Overall, clinical experience is limited, with no comprehensive evaluations of plan quality and no comparative clinical studies.

She highlighted the particular challenges of breast cancer treatments, which account for 25-30% of cases in her radiotherapy department. “When we place a breast cancer patient upright, we lose the natural breast separation, so have much more difficulty in hitting the target and avoiding the contralateral breast,” she explained. “This exemplifies how upright is not a plug-and-play replacement for a conventional supine workflow.”

“Are we sure we would like to have upright as the standard radiotherapy delivery option by 2035 or do we want to push our efforts somewhere else?” Marrazzo concluded. She would prefer a focus on introducing technologies such as AI-driven planning and contouring, fully adaptive workflows, ultra-hypofractionation or biology-guided treatment adaptation. “These are all solutions that can be software-driven, scalable and compatible with existing supine infrastructure.”

The motion for protons

With half of the audience already agreeing that upright proton therapy will become mainstream, Petra Trnkova from Czech Technical University had perhaps a slightly easier task as she presented the case for upright protons. Nevertheless, she began by suggesting that her opponents are simply “scared of progress and won’t accept that, even without evidence, we can move forward in radiotherapy”.

Trnkova reiterated the benefits of upright radiotherapy cited by Kron: favourable patient anatomy, lower installation cost, improved sustainability, and patient-centric management. “For proton therapy, these improvements are much more significant,” she noted.

For starters, upright systems could help address the massive disparity in access to proton therapy around the globe. Sharing a map showing how proton therapy facilities are mostly distributed in wealthy countries, Trnkova noted: “My opponents may tell you that it’s not possible to do this by 2035, but when you look at this map, I ask you, can we wait any longer?”

Increasing access to proton facilities is enabled by the extreme size reduction when eliminating the need for a large rotating gantry, enabling proton therapy systems small enough to fit in a standard linac vault. Upright proton therapy can also reduce machine complexity, increase rotation speed and lower energy consumption – reducing costs, improving system upgradeability and increasing environmental sustainability.

“Another consequence of smaller facilities is we can really have patient-centred care,” Trnkova added. Recalling the 10 to 15 year linac lifetime mentioned by Marrazzo, she suggested another option: “You can replace your linac with proton therapy. Then you can have the full set of treatments available for each patient”.

Upright proton therapy could also ease the introduction of new treatment techniques, such as proton arc therapy, which offers dosimetric benefits over intensity-modulated proton therapy, but it is difficult to deliver with a gantry. It could also enable in vivo dosimetry, using shoot-through protons for range verification, or mixed-beam delivery of protons and photons.

“Upright positioning offers many opportunities, it’s the only way towards the democratization of proton therapy,” Trnkova concluded. “Stop asking what opportunities upright radiotherapy brings, start asking what you can do to bring it faster to clinical practice.”

The reality check

The final speaker, Carles Gomà from Clinic Barcelona in Spain, reflected upon what makes a good radiotherapy system. “In my view, it’s a three-legged stool: beam delivery, imaging and immobilization,” he said. “And progress comes with a combination of the three.”

For example, focusing too heavily on beam delivery and imaging can lead to immobilization being forgotten. “Immobilization means comfort, and if we are comfortable, we are still,” Gomà explained. “I cannot care less how many papers say patients are more comfortable in an upright position,” he added, pointing out that people will pay five times more to fly in business class where they can lie down.

The other reason cited for moving to upright proton therapy is its lower cost. “But is proton therapy expensive?” Gomà asked. He described the situation in Catalonia, which has a population of eight million and in 2018 spent Euro 42.2M on external-beam radiotherapy. “This is exactly the same cost as one immunotherapy drug for the same population,” he pointed out. “Proton therapy is not expensive; photon therapy is ridiculously cheap.”

Gomà also considered whether “suboptimal protons” are better than photons. “I’m going to answer no,” he said, describing two recent phase III, randomized trials comparing photons with protons for oropharyngeal cancer. The US trial concluded that proton therapy provides a new standard-of-care option, but the UK trial reported no difference between the two modalities.

“Let’s learn from history and not repeat the same mistakes,” he concluded. “True progress is improvement without compromise. If we want to make the stool higher, we have to work on all three legs at the same time.”

The debate concluded with decisive a final vote: while support for upright photon therapy reduced a little, over two-thirds of the audience believed that upright proton therapy will indeed become mainstream and standard by 2035.

Writing on LinkedIn, session co-chair Ye Zhang from the Paul Scherrer Institut noted: “The debate sparked an inspiring shift in perspective, with final voting showing slightly increased scepticism toward mainstream upright photon therapy (dropping from 23% to 18% support), but a dramatic surge in favour of upright proton therapy, which jumped from 47% to a 69% majority.”

The post ESTRO debate reveals rising confidence in upright proton therapy appeared first on Physics World.

Nigeria is Africa’s most populous country and one of its largest economies, which puts enormous pressure on its electricity system. At the same time, the country has committed to reaching net‑zero emissions between 2050 and 2070. Today, Nigeria’s power sector is underpowered, unreliable for many citizens, and heavily dependent on fossil fuels and diesel generators, which are costly and polluting.

This study explores pathways for Nigeria to reach net‑zero emissions by 2050, 2060, and 2070, focusing on which technologies would be required. Across all scenarios, solar power becomes the backbone of the system, providing 37–55% of electricity by 2050 and remaining central in the two longer term scenarios. Nuclear power also plays a major role when allowed, but faces barriers such as high upfront costs, regulatory capacity, and public safety concerns. If nuclear is excluded, Nigeria must rely even more on solar and on gas with carbon capture and storage (gas-CCS).

Although transitioning to net‑zero requires significant upfront investment, the study finds that a clean electricity system is cheaper overall than continuing with fossil fuels, and earlier transitions do not significantly increase total costs.

The authors conclude that Nigeria should build a balanced clean‑energy mix (solar, hydro, nuclear, gas‑CCS), rapidly scale up solar deployment, strengthen institutions, mobilise international and private financing, and coordinate regionally to ensure a reliable, affordable, and achievable transition.

“Nigeria’s electricity transition is not only a climate challenge; it is also a development and reliability challenge. Our analysis shows that solar power will be central to any net-zero pathway, but achieving an affordable and dependable electricity system will require a diversified mix of clean technologies, stronger institutions, and sustained investment in the grid and supporting infrastructure.” – Dr Michael Dioha, Clean Air Task Force

Do you want to learn more about this topic?

The zero-emissions cost of energy: a policy concept Colin Beal and Carey King (2021)

The post Solar at the centre of Nigeria’s future appeared first on Physics World.

The lines between separate scientific disciplines are becoming more blurred. Solving today’s problems often requires teams of scientists from a range of specialisms. But multidisciplinary collaboration also has challenges, in particular the need to “speak the same language”, ask the “right” questions and be familiar with techniques and knowledge that exist in other fields.

To see the importance of finding a common language look no further than the rapid uptake of large language models (LLMs) such as ChatGPT. LLMs can be convenient research aids, but the information provided by them is not always accurate. We can ask LLMs questions about another field, but without existing domain knowledge we cannot always tell if the answers are reliable.

Getting up to speed with a new research field can be tricky – it’s difficult to understand everything fully, but tempting to think that you do. There’s a parallel with sport where it might sound reasonable, say, to assume that mixed martial arts (MMA) fighters can easily become boxers. However, the evidence suggests that MMA fighters often struggle against professional boxers even though fist fighting uses a subset of the skills needed to be successful in MMA.

Back in academia, it’s common to get pushback from “real experts” whenever grant proposals or papers drift too far outside one’s own comfort zone. Nevertheless, discipline mixing is needed more than ever. Today’s problems often straddle different scientific disciplines: how to treat large, complex datasets, for example, is a common challenge in many different fields.

Look up at the stars and not (just) down at your tea

We realized this recently in our work at Queen’s University Belfast, which has been pushing for researchers to share their data analysis strategies with colleagues in other fields. In our case, we had been collaborating with Yicong Li at the Institute for Global Food Security on infrared and ultraviolet-visible spectroscopy and machine-learning models for monitoring the freshness of fish, which required only a few samples for analysis.

However, many food studies need hundreds or thousands of samples to be analysed and class imbalances can quickly arise in which some types of foodstuff have more examples than others. This can then lead to training datasets that do not produce predictive models. One example is tea, which Li has been investigating recently, again via spectroscopy and machine learning, using many samples from all over the world.

Li was trying oversampling, which creates synthetic data to equalize class imbalances. Yet over in the Queen’s physics department, we discovered another strategy was being used to classify problems in astrophysics. Matt Nicholl and PhD student Xinyue Sheng had been working on predicting the classes of energetic cosmic explosions, based on an image of the galaxy where they occurred. They wanted to train their model to find particularly rare classes, so their training set had the same problem: there were only a handful of examples of some classes of interest.

In addition to oversampling, they were also using a “weighted loss function” in their training, in which weights were inversely proportional to the number of examples in a given class. Their approach led to a substantial improvement in their astrophysics application, but it turns out the basic idea is completely general in nature and can be just as easily applied to tea.

Sleeping beauties

Knowledge exchange does not only concern data, but sometimes a whole set of ideas. An interesting study of citation metrics in 2015 by researchers at Indiana University found that there is a class of papers that receive very little attention for years before suddenly shooting skywards with a deluge of citations. Notably, these “sleeping beauty” papers include Albert Einstein, Boris Podolsky and Nathan Rosen’s work in 1935 examining non-locality in quantum mechanics, which led to John Bell’s theorem in 1964 and ignited significant interest in the original “EPR” paper.

Such citation trends can arise because the papers’ findings are adopted by researchers in a different field. Other similar instances include work in the 1930s and 1940s on hydrophobic theory, which describes how certain substances minimise their contact with water. Yet perhaps the sleepiest of sleeping beauties is the principal component analysis (PCA) work by Karl Pearson, which slumbered for over 100 years before “awakening” in the early 2000s.

PCA – a technique that simplifies complex datasets by reducing the number of variables while minimizing information loss – had already been gaining traction during the 1980s and 1990s when matrix calculations became easy for computers alongside the development of statistical software packages and open scripting environments. In research papers published today it would be unusual not to see PCA used as an exploratory tool for multivariate dataset analysis.

As these examples show, it’s crucial that communication channels are open between varying fields. However, too many academic researchers can get siloed. Interdisciplinary science hubs are one way to break down barriers, acting as spaces to exchange ideas between scientists.

One example that we have been involved with is Smart Nano NI, which is a consortium of universities and photonics-based companies in Northern Ireland. It recently released TITAN, a bio-process analysis system based on gold nanostructured chips, for real-time bio-analysis. Smart Nano NI is now moving from benchtop to backpocket, looking to develop fully miniaturized sensing devices by integrating different kinds of photonic components like lasers, filters and detectors, all on the same chip.

Elsewhere, centres for doctoral training – such as the Photonic Integration and Advanced Data Storage programme with the University of Glasgow – bring together groups of PhD students to work on various projects under a common theme. These schemes not only foster new ideas with the student cohort but bring together academics to bridge different parts of research. Either way, we are getting people talking and interested in emerging scientific questions.

So if you are sitting on a problem, there might be a chance that someone in a different field has solved it or at least offered the tools to do so. As our sky-gazing friends might say, “There is nothing new under the Sun.”

The post Why interdisciplinary science is needed more than ever appeared first on Physics World.

A bolometer that can measure absorbed energy at a resolution of less than a zeptojoule (10⁻²¹ J) has been unveiled by Mikko Möttönen and colleagues at Finland’s Aalto University.  Their device could soon enable researchers to measure the energy of individual lower-energy photons – leading to new opportunities in quantum computing and information processing.

A bolometer detects radiation using two main components: an absorber, which heats up as it captures incoming radiation, and a thermometer, which converts this temperature rise into a measurable electrical signal. Bolometers are some of the most sensitive radiation detectors in use today.

Indeed, high-performance bolometers based on nonlinear oscillators, superconducting qubits or Josephson junctions are sensitive enough to detect individual microwave photons with energies of about 10⁻²³ J. However, these devices are not able to resolve photon energies very well and only work over certain photon energy ranges.

Normal sandwich

A Josephson junction comprises a normal (non-superconducting) material sandwiched between two superconductors. Thanks to the proximity effect, superconducting Cooper pairs of electrons can penetrate some distance into the normal material. So, if the normal material is narrow enough, a supercurrent will flow across the junction.

“We started to build bolometers based on so-called proximity superconductivity around 2010 when I obtained my European Research Council Starting Grant,” says Möttönen.

In the team’s previous bolometer design, the normal material (a metal) absorbs photons, thereby increasing the temperature of the Josephson junction. This results in a shift in the impedance of the junction – and this shift is measured and related to the amount of energy absorbed. A key feature of this approach is the integration of the absorber and thermometer functions into a single structure.

In their latest study, Möttönen’s team has expanded their design to include multiple junctions. “We used gold-palladium (AuPd) and aluminium as the materials such that we can independently engineer the absorber part of the device from the thermometer part,” he describes. “We can optimize the strength of the superconductivity in the thermometer for high sensitivity.”

Impedance match

Their design consists of a AuPd nanowire (a normal metal), split into two segments. The first acts as an absorber and is tuned to match the impedance of the transmission line delivering microwave photons. This ensures that the highest possible amount of microwave power is transferred to the nanowire, across a broad range of photon energies.

The other nanowire segment acts as the thermometer. Superconducting aluminium islands are placed next to the nanowire, creating a series of Josephson junctions. By measuring inductance shifts across the junctions the team determined the energies of single photons at resolutions smaller than 1 zJ.

The researchers are hopeful that their design will be developed to create practical detectors of single lower-energy photons – and potentially other types of particle. This would be especially useful for calibrating the components of quantum computers.

“We will use this sensor in what I refer to as an autonomous quantum processing unit to measure qubits at millikelvin temperatures and feed back to information through millikelvin controllers and microwave sources,” Möttönen says. “This will dramatically reduce the price of quantum computers in the future.” The detector design could be also adjusted to receive telecom signals at the single-photon level – providing an ideal platform for the ultra-secure communication method of quantum key distribution.

The post New bolometer achieves sub-zeptojoule resolution appeared first on Physics World.

Fancy some more? Check out our puzzles page.

The post Quiz of the week: which UK university plans to shed almost 30% of its physics staff? appeared first on Physics World.

More than half a century after the final Apollo mission, humans are returning to the Moon. The latest episode of Physics World Stories reflects on Artemis II – the April 2026 mission that flew four astronauts around the Moon, travelling further from Earth than anyone before them.

The mission marks a major step towards returning humans to the lunar surface and paving the way for a future mission to Mars. It also marked an important societal milestone, as the crew included the first woman, the first person of colour, and the first non-US citizen to fly to the Moon.

Ambre Trujillo of the Planetary Society discusses the excitement surrounding humanity’s return to lunar exploration. In conversation with host Andrew Glester, Trujillo reflects on witnessing her first rocket launch and explains why she sees the Artemis programme as every bit as significant as Apollo for a new generation. Looking ahead, Artemis III in 2027 will test the rendezvous and docking capabilities needed between Orion and commercial landing systems, before Artemis IV aims to return humans to the lunar surface in 2028.

Targeting greener spaceflight

The episode also examines the environmental impact of spaceflight with Alexis Normand, whose company Greenly specializes in carbon accounting. Normand argues that while the space industry’s overall footprint remains relatively small, its ambition and global visibility give it enormous power to inspire wider technological change. Liquid hydrogen was critical in powering Orion’s liftoff and later thrusting it towards the Moon, and could one day help transform aviation into a low-carbon industry. But that hinges hydrogen production itself becoming greener through renewable-powered electrolysis and broader electrification.

Blending lunar ambition with climate innovation, the episode explores how missions to the Moon could help shape the future both in space and here on Earth.

• Find out more about the Artemis II mission in this Physics World feature by science writer and astronomer Keith Cooper

The post Back to the Moon: inside the Artemis II mission appeared first on Physics World.

Engineering light transmission through opaque media is possible thanks to the development of a classical wavefront shaping technique first reported in 2007. Researchers have now demonstrated a quantum entanglement-based method that enables selective image transmission through complex disordered materials.

“We discovered that there might be a way to use quantum properties of light to actually help or improve the problem of imaging through scattering media,” explains Hugo Defienne, a quantum optics researcher at the Paris Institute of Nanosciences (CNRS/Sorbonne University).

In two new research papers, Defienne and his colleagues show how to leverage quantum correlations to engineer incoming light to overcome the scrambling that occurs when it passes through “opaque” scattering materials. The approach could point towards alternatives to the solution pursued so far for unscrambling such light – and could even provide a route towards secure communications, by rendering channels transparent to entangled photon pairs, while remaining opaque to a classical light.

“These works offer a particularly elegant perspective, showing that for spatially entangled photons, the space of wavefront corrections that can compensate scattering is significantly larger than in the classical case,” comments Yaron Bromberg, head of the Complex Photonics Lab at the Hebrew University of Jerusalem in Israel.

Quantum opportunities

In 2007, Allard Mosk and Ivo Vellekoop, both then at the University of Twente in the Netherlands, reported how measurements of the intensity spatial distribution of light distorted by transmission through an opaque scattering material could be used to control the propagation of light and refocus it at the output, effectively turning the scattering material into a lens.

Building on this, in 2010 Sébastien Popoff and Sylvain Gigan showed that they could identify a transformation matrix between the original beams and the transmitted beams, such that applying the inverse to the initial wavefront using a spatial light modulator would allow the original beams to emerge undistorted. Later developments have applied the technique to quantum light. However, being based on intensities of the transmitted light alone, these have not actually exploited light’s quantum properties.

Defienne was working on both the quantum properties of light and the challenge of unscrambling scattered light signals when he began to mull over how to leverage quantum properties in this feedback approach. “We discovered that when you use quantum light, there are many ways of actually unscrambling the light that do not exist when you use a classical system,” he tells Physics World.

Correlation correction

To understand how solutions to the problem multiply for the quantum scenario, it helps to consider a certain type of quantum entanglement that leads to spatially correlated photons. Measure the end point of a photon that’s spatially correlated with another, and the end point of its partner photon will be dictated by the correlation. While scattering media also scramble spatial correlations, a spatial modulator can also invert the scrambling process to retrieve the original spatial correlations.

The quantum bonus comes because whereas with classical light the scattering medium only appears transparent when a one-to-one correspondence between incoming beam and output beam is achieved, there are additional solutions that return an apparently identical spatial correlation distribution between incoming and output entangled photons.

Defienne and his colleagues report the derivations for the quantum approach in Optica. They also demonstrate the approach using a single photon avalanche diode to detect the quantum correlations of light transmitted through a film of paraffin, before feeding it back into a spatial light modulator that adjusts phases to manipulate spatial correlations.

“Conceptually, it’s exactly the same idea,” says Defienne. Nonetheless, almost 20 years on from Mosk and Vellekoop reporting their approach for unscrambling light, this is the first time it has been successfully applied to the quantum properties of light. “It’s just very complex,” Defienne adds. The weak photon pair source, scattering losses in the medium and imperfect detection all pose challenges, such that it can take a long time to have enough data for the required statistics.

“In fact, this is only possible because now we have single-avalanche diode cameras,” says Defienne, noting that these became available with the required sensitivity and frame rate about five years ago. “With any previous camera technology, this is totally impossible.”

Leveraging the quantum properties in this way means that the spatial light modulator unscrambles the quantum correlations while leaving the classical beam still scrambled. The researchers suggest this could serve as a quantum filter that might be useful for blocking nefarious signals intended to muddle transmitted data – by encoding data in quantum correlations it’s possible to block fake data, so long as it is classically encoded. They demonstrate this filtering process in their Nature Physics paper.

“These results mark a significant breakthrough achieved in experimental samples,” says Sushil Mujumdar from the Tata Institute of Fundamental Research in India, who was not directly involved in the current research. Mujumdar has been working on optimizing wavefront shaping algorithms for quantum light, in particular where the incoming photon count is low. He adds: “The logical segue to this work would be the application of these techniques to thicker and realistic media, which, as acknowledged in the paper, become challenging because of drastically low signal photons, characteristic of the quantum domain.”

Indeed, Defienne and his colleagues are already looking into “some new shaping approach that could be better” for quantum correlated photons passing through, for example, a layer of paint instead of paraffin. They are also looking at the potential to leverage the optical nonlinearity of entangled photon optics for quantum reservoir computing.

The post Entangled photons open up potential applications of anti-scattering optics appeared first on Physics World.

There are craters on the Moon where the Sun never shines – and researchers in the US and Germany have shown that these shady locations would be ideal for housing lasers that are more stable than similar devices operated on Earth.

Writing in the Proceedings of the National Academy of Science, Jun Ye at NIST and the University of Colorado and colleagues explain the benefits of installing a silicon optical cavity in a permanently shaded crater. Such a cavity is a block of silicon with internally facing mirrors at opposing ends. Light from a commercial laser is shone into the cavity where it bounces back and forth, growing in intensity and coherence. The length of the cavity defines the frequency of the trapped light. So if the cavity is machined to a very high precision, then the cavity light has a very narrow frequency range.

Some of this light is extracted from the cavity, creating a source of high-quality laser light. To ensure the stability of the laser, the cavity can be cooled to cryogenic temperatures to minimize thermal fluctuations. Now, Ye and colleagues have shown that this stability can be improved significantly if a cavity is operated in a shady nook on the Moon.

Cold vacuum

There are more than 300 regions of the Moon that are in permanent shadow. As well as being enveloped in darkness, these regions tend to maintain a steady temperature of about 50 K. While the Moon has no real atmosphere, it is not surrounded by a perfect vacuum. Radioactive decay and bombardment by meteorites, the solar wind and sunlight liberates molecules from the surface and these will linger briefly before escaping into space. Because dark craters are not subject to bombardment, there should be fewer gas molecules in these regions – and therefore a better vacuum than on the surface. Indeed, the team calculates that pressures of less than 10⁻¹⁰ Pa should exist in these craters, which is well within the ultrahigh vacuum regime.

As a result, dark craters should be a perfect environment for operating a silicon optical cavity. There it would experience a small number of collisions with gas molecules, boosting its stability. What is more, by radiating heat out of the crater and into space, Ye and colleagues reckon that an optical cavity could be further cooled to a chilly 16 K. At this temperature, silicon will neither expand nor contract in response to tiny temperature fluctuations – further stabilizing the output of the cavity.

According to the researchers’ modelling, such a cavity would have a very low thermal noise-limited stability of 10⁻¹⁸ and a coherence time exceeding 1 min. This performance, they say, is ten times better than that achieved by the best cavities operated on Earth.

Testing Einstein

The team proposes several different uses for light emitted by the cavity. Because it would have a very stable frequency, it could be used as a very precise lunar time signal. This would be very useful for the navigation on, or near to, the Moon as well as for scientific experiments – including those that test Einstein’s general theory of relatively.

Ultrastable lasers would also allow scientists to create long-baseline interferometers for astronomical observations, including the detection of gravitational waves. Furthermore, the cavities themselves could also be used as detectors. Gravitational waves at certain frequencies would affect the output of a cavity – as could hypothetical interactions between silicon atoms and dark matter.

Using a high-powered relay laser, the cavity signal could be transmitted to lunar satellites that contain atomic clocks – creating a timing network similar to Earth’s global navigation satellite systems such as GPS. Furthermore, light from the cavity could be used to create a quantum network that stretches from the Moon to the Earth.

Team member Yiqi Ni works for the US-based company Lunetronic, which is developing technologies for use in permanently shadowed craters. Ni says that a silicon optical cavity could be operated in low-Earth orbit within two years – and be installed on the Moon within three to five years.

The team also includes researchers from the US National Institute for Standards and Technology (NIST) and PTB, which is Germany’s national metrology and standards institute.

The post Building a better laser on the Moon appeared first on Physics World.

Here’s how the game works:

1. 1. Enter a word guess – in this game the word has six letters.
   2. After submitting your guess, each letter in the guessed word is coloured to provide feedback:
      • Green: The letter is correct and is in the correct position in the target word.
      • Yellow: The letter is correct but is in the wrong position in the target word.
      • Grey: The letter is not in the target word at all.
   3. Using this colour feedback, refine your next guess.
   4. Continue guessing until you correctly identify the hidden word(s) or run out of attempts.

If you need any hints, read the article here.

Fancy some more? Check out our puzzles page.

The post Word wave puzzle no.4 appeared first on Physics World.

Noise is the enemy of many computing paradigms. Conventional computers are power hungry because they must operate at energy levels well above those of electronic fluctuations in silicon. The problem is much more acute in quantum computing, where noise is a significant barrier to creating practical processors.

But what if we could use noise as a computational resource? That is the idea behind thermodynamic computing – which is the focus of this episode of the Physics World Weekly podcast. My guest is the theoretical physicist Stephen Whitelam – who joins me down the line from Lawrence Berkeley National Laboratory in the US.

• “Generative Thermodynamic Computing” by Stephen Whitelam

The post Thermodynamic computing: noise as a resource, not an enemy appeared first on Physics World.

Static electricity is an everyday phenomenon, but it is not well understood. Researchers at the University of Chile have now added another piece to the puzzle by conducting experiments on the charge distributions of free-falling particles. They found that same-sized particles within the sample had the same range of surface charge densities, suggesting that particle size plays a major role in static electricity. Their work could improve our understanding of how charge behaves on insulating surfaces, with implications in areas ranging from planet formation to lightning generation in volcanic plumes and clogging in industrial processes.

Static electricity is also known as contact electrification because it occurs when charge transfers from one object to another as the two touch each other. (Think of rubbing a balloon on someone’s head to make their hair stand on end). The phenomenon is present in many situations, including pollen transport, grinding coffee, and ash particles in volcanic plumes, which can generate lightning. Electrostatic charging also creates strong electric fields in sandstorms on Earth and dust storms both here and on Mars. Charged dust could even be involved in the formation of rocky planets.

To understand and model the effects of electrostatic charging, researchers need to find out how particles become charged and, once that happens, how these charges are distributed. “In an ideal experiment, we could study a large ensemble of same-material, initially neutral grains,” says Nicolás Mujica, the physicist who led the study. “After many contacts and collisions between the grains, we should observe a stationary and stable charge probability distribution function that has both positive and negative charges.”

Researchers have previously observed this effect by imaging the trajectories of particles in free fall as an electric field was applied to them in microgravity conditions. The charge probability distribution functions (PDFs) measured in these experiments are generally non-Gaussian, with “fat” tails that may point to the existence of memory effects in the charge exchange process between the particles. “It is much more likely to have highly charged particles in an ensemble that what we would naively expect,” Mujica says.

Free-fall videography technique

Mujica and colleagues measured the charge distributions of ZrO2:SiO2 composite particles using a free-fall videography technique they developed in a previous study. The particles ranged from 172 to 545 μm in diameter and each sample focused on a single size. As well as buying the particles from the same vendor to ensure they were as identical as possible, the team further characterized them using x-ray fluorescence (XRF) and atomic force microscopy (AFM) to determine their precise chemical composition and surface roughness, respectively.

In their experiments, the Chile researchers released the particles from a 3 m drop tower, which is essentially a huge, transparent hourglass structure under vacuum with electrodes on either side that generate a static electric field. Inside this tower, the particles rub against each other during their quasistatic flow and become either positively or negatively charged in the process. The static electric field accelerates these charged particles sideways, and the researchers measure this acceleration by capturing the particles on video as they exit the tower. By combining the particles’ known mass with their measured accelerations, the team can calculate the particles’ charges.

Next, Mujica and colleagues plotted the probability that a certain amount of charge would be found on a given particle. Since charges could be either positive or negative, all the PDFs, regardless of particle size, resembled non-Gaussian curves with peaks at zero charge. However, the widths of these curves varied systematically with the surface areas of the particles. According to the researchers, this result indicates that the charging of the particles depends on the particles’ size.

Towards a microscopic model of charge exchange

The researchers say their study began with a simple question: how do planets form? “There are some important missing pieces in this big puzzle and one of them is the effect of electric charges,” Mujica says. The team’s results, he says, are evidence that charge can indeed help particle clusters to form in space.

Their main challenge, he recalls, was constructing the drop tower. The first prototype did not work because of a fundamental design problem, and while the second worked better, it broke after a few years because of the forces (about 40 kN) exerted on each side of the chamber due to the vacuum within. “The third and current version is working fine and we expect it to live long enough to take more useful data,” Mujica says.

The researchers, who report their work in Physical Review Materials, say their next step will be to develop a microscopic model of charge exchange from which they can determine the measured charge distributions. “We will then adapt this model for mixtures of particles, either of different sizes or materials, and try to simulate more realistic situations, comparing the predictions with measurements,” says Mujica.

“It has also been recently demonstrated that adventitious carbon, a thin, ubiquitous layer of carbonaceous contamination (typically a few nm thick) that forms on most surfaces exposed to air, plays a big role in the way oxide particles exchange charge,” he adds. “We therefore intend to study the charge segregation that usually occurs between large and small grains and the effect of surface cleaning processes.”

The post Particle size affects contact electrification appeared first on Physics World.

MRI is a powerful diagnostic imaging tool, with more than 100 million scans performed worldwide each year. While MR signals contain rich information from multiple molecules and numerous physical and biological processes, current clinical MRI exams rely solely on signals from water molecules in tissues and generally only obtain one tissue biomarker at a time. But MRI could do so much more.

A research team headed up at the University of Illinois Urbana-Champaign has done just that, devising a new MRI technique – multiplexed MRI (MRx) – that enables simultaneous mapping of multiple molecular signals using a standard clinical 3 T MRI scanner.

The barrier to performing multiparametric imaging with conventional MRI lies in the “curse of dimensionality”, in which high-dimensional imaging requires prohibitively long scan times. Multimolecular MRI, meanwhile, is limited by weak signals from brain metabolites and neurotransmitters (typically 1000–10,000 times weaker than proton-based signals from water molecules), which often overlap, making them difficult to detect and separate.

“MRx overcomes these challenges through specialized data acquisition and processing strategies,” explains study leader Zhi-Pei Liang. “During data acquisition, MRx simultaneously excites and encodes all detectable molecular signals with sparse sampling to achieve high imaging speed. During data processing, MRx employs physics-driven machine learning methods to separate and quantify the different signal components.”

Reporting their findings in Nature, the researchers demonstrate high-resolution mapping of 22 quantitative biomarkers of the whole brain in a single scan. They also show how a new sparse sampling scheme enables acquisition of these biomarkers in just 14 min – significantly shorter than clinical multi-contrast MRI protocols that can take up to an hour.

“Our main motivation was to develop an ‘omni’ imaging technology that fully harnesses the rich biological information embedded in magnetic resonance signals, enabling us to unravel the structural, physiological and molecular fingerprints of brain function and diseases,” says Liang.

In vivo studies

MRI is widely used within brain tumour diagnosis to evaluate tumour location, size and extent, and blood–brain barrier disruption. However, standard MRI scans do not directly reveal the underlying pathophysiological changes and tumour heterogeneity. MRx, on the other hand, can acquire a wide range of biomarkers that provide valuable information on processes such as neuronal loss, energy metabolism, axonal damage, hypoxia, demyelination and many more.

To test the technique, Liang and colleagues performed MRx imaging on patients with clinically diagnosed brain tumours, using machine learning to combine the measured biomarkers into a single variable defining the tissue state at each pixel. This MRx “tissue state index” could differentiate eight distinct tissue states: grey matter; white matter; cerebrospinal fluid; oedema (fluid build-up); meningioma; low and high-grade oligodendroglioma; and glioblastoma. Standard multiparametric MRI failed to separate these states.

This ability to accurately characterize tissue states could enable a range of essential clinical tasks, such as grading low- versus high-grade brain tumours, for example, or separating glioblastoma from oedema during radiation therapy planning.

MRx could also prove invaluable for lesion characterization in multiple sclerosis (MS), a critical process for stratifying patients, planning treatment and predicting disease progression. The researchers demonstrated that MRx of patients with MS could differentiate active and chronic MS lesions without requiring contrast agents (as in current practice), attributed to the technique’s ability to visualize biomarkers specific to individual pathophysiological processes.

Such MRx biomarkers also helped to predict lesion progression, by capturing key pathophysiological features that cannot be revealed by conventional MRI, a feature that could enable early interventions and improve patient outcome.

Beyond cancer and MS, many other brain diseases could also benefit from MRx, including stroke, epilepsy and Alzheimer’s disease, for example. “MRx is expected to open up new opportunities for brain mapping and for precision healthcare of brain diseases, including neurological and neurodegenerative disorders,” says Liang.

For the proton-based studies reported in this latest study, MRx was performed without needing any modifications to the MRI scanner hardware. Instead, the method is implemented using a new pulse sequence for data acquisition plus custom software for data processing. Liang notes that extending MRx to include multiple nuclei – such as sodium, phosphorus, and deuterium – will require specialized multinuclear RF coil hardware.

“Our current efforts are focused on further improving the robustness and reliability of MRx under practical clinical imaging conditions, to facilitate both scientific studies and clinical translation,” he tells Physics World, noting that MRx has already been licensed (through Siemens) to imaging centres worldwide for evaluation of its clinical potential. “We are also expanding the technology to map additional molecular species and, ultimately, to enable multinuclear multiplexed imaging beyond protons.”

The post Multiplexed MRI expands the power of conventional brain imaging appeared first on Physics World.

Life sciences: reliable conditions for pharmaceutical freeze drying

Freeze drying (lyophilization) plays an important role in the manufacture of pharmaceuticals extending shelf life by removing water via sublimation under vacuum conditions. Because these processes run over long cycles, stable and contamination-resistant vacuum measurement is essential.

Thyracont’s VCP transducer is designed for such applications. Its platinum-rhodium filament provides high resistance against corrosion and contamination, supports sterilization and reliable operation under thermal stress. Operating in the fine vacuum range (1000 to 5 × 10^−⁴ mbar), it ensures stable process control in freeze-drying systems.

“Long-term stability and resistance against corrosive process media are decisive factors in freeze-drying processes. The VCP was specifically engineered to maintain reliable performance even withstanding steam sterilizations,” explains Frank P Salzberger, CEO of Thyracont.

High-tech and research: enabling analytical precision

Many of the cutting-edge instruments used in analytics and R&D operate under vacuum – including those used for mass spectrometry and materials testing. In applications such as beverage gas analysis, the VSP63MV Pirani transducer enables precise monitoring in the 1000 to 10⁻⁴ mbar range, supporting zero adjustment of the mass spectrometer, which is essential for the reliable detection of trace contaminants at very low concentrations.

The analysis of the thermomechanical properties of materials is necessary for the development of cryogenic technologies including those used in quantum technologies. This involves cooling materials and devices to very low temperatures and measuring how their physical properties change. Thyracont vacuum gauges such as the VSP63DL and VSM77D cover fine and high vacuum ranges down to ultra-high vacuum conditions, enabling stable thermomechanical characterization of materials at extreme temperatures.

Semiconductor and coating processes: stability in complex systems

In semiconductor manufacturing, wafer bonding requires tightly controlled vacuum conditions to ensure contamination-free and uniform layer formation. During initial evacuation, Thyracont’s VSC43MA4 is used to monitor roughing and bypass pumping stages.

In subsequent high-vacuum stages, Smartline VSM transducers provide reliable measurement from atmospheric pressure to ultra-high vacuum, combining Pirani and cold cathode technologies with optimized range switching for stable operation.

“In semiconductor wafer bonding, it is essential to maintain stable measurement across the full pressure range – from roughing to ultra-high vacuum. Our Smartline VSM series ensures exactly this seamless transition,” says Salzberger.

In optical coating applications, this approach ensures continuous monitoring while protecting sensitive sensor components.

Industrial vacuum processes: distillation and thermal treatment

Short-path distillation relies on precise vacuum control (typically 1 × 10^−³ to 1 mbar) to enable gentle separation of heat-sensitive substances such as fragrances. A thin film is formed inside the chamber, and evaporation occurs at reduced temperatures, preserving delicate compounds.

Stable pressure control is essential to ensure consistent product quality. Devices such as the VD64P and VD850 support monitoring and control functions including switching outputs, leak detection, and integrated data logging for process documentation.

Peter Gerlesberger, development manager at Thyracont explains, “Reliable leak testing ensures that vacuum chambers and systems meet the required process conditions. With the VD850 users can quickly and reliably determine the magnitude of the leak rate”.

Vacuum furnaces face similar requirements under high-temperature and contamination conditions. The VD850, as well as VSH transducers (Pirani/hot cathode), enable reliable pressure measurement across furnace inlet and outlet zones.

Packaging applications: quality control in food safety

Vacuum packaging plays a crucial role in in the food industry, extending shelf life and reducing food waste. Ensuring consistent vacuum levels is critical for product safety and quality.

Testing is performed by replacing the food with a vacuum gauge and monitoring the pressure after sealing. The compact VD810 can be temporarily integrated directly into packaging, thereby simulating real-world process conditions.

The built-in piezo-ceramic sensor measures absolute and relative pressure in a rough vacuum and records pressure curves with timestamps. The recorded measurement data can be downloaded via USB or, optionally, via Bluetooth LE and used for process analysis and quality documentation.

The common thread

Across industries, from life sciences to semiconductor manufacturing, Thyracont vacuum measurement technology enables precise, stable, and reliable process control under demanding conditions. By combining robust sensor design with wide measurement ranges and intelligent system integration, these instruments contribute to the performance and quality of modern industrial and research applications.

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Ultra-precise electron beams can rearrange atoms in a 3D crystal lattice and create structures not found in nature, an international team of researchers has shown. The work could have implications for quantum simulation and atomic-scale manufacturing.

 The 1986 Nobel Prize for Physics was divided between three researchers. Half was split between Gerd Binnig and Heinrich Rohrer of IBM’s Zurich laboratory for their development of the scanning tunnelling microscope (STM). The STM’s ability not just to image but to move atoms was famously demonstrated three years later, when Don Eigler and Erhard Schweizer of IBM Almaden in California produced a picture of 35 xenon atoms precisely placed on a crystal of nickel to spell out the letters “IBM”. STMs have become widely used in surface analysis. However, they can only manipulate 2D surfaces, are painstakingly slow and require high vacuum and ultracold temperatures.

The other half of the 1986 prize went to Ernst Ruska of Germany’s Max Planck Society for his invention of the electron microscope – which can image samples with atomic resolution. Until now, however, electron microscopes had not been able to deterministically manipulate atoms because their high-energy electron beams tend to break bonds randomly within a crystal.

Now researchers in the group of Frances Ross at Massachusetts Institute of Technology led by Julian Klein, together with Kevin Roccapriore of Oak Ridge National Laboratory and others, used Oak Ridge’s ultra-precise, extremely stable, focused electron beam to penetrate around 13 nm into a crystal of the layered van der Waals material chromium sulphide bromide.

Interesting crystal structure

 “The material has a very interesting crystal structure,” says Klein; “One individual layer has a mixture of sulphur and chromium atoms, but then on both sides of this layer there are bromine atoms sticking out in both directions. And when you stack those crystals you create atom-sized gaps between the layers.”

When the electron beam is positioned within 20 pm of its target and then moved slightly in a specific direction, the electrons in the beam can nudge the chromium atoms in the line of fire out of their original positions into the target unoccupied sites. This creates lattice defects called vacancy–interstitial complexes. Computer simulations suggest that, owing to interlayer interactions, movement of the chromium atom in one layer should encourage the transformation of layers above or below. Ross says that “[the transformed layers] do form in a timed sequence, but we can’t tell in what order they’re transforming”.

 By carefully manipulating the electron beam across the surface of the crystal, the researchers can create an array of vacancy–interstitial complexes: “Julian and Kevin have a series of images at different times,” says Ross; “You can see the quality of the result just gets better and better…The beam has to be exactly on that column of atoms because otherwise some of the energy is going to go into the wrong place and disrupt the rest of the lattice.”

More robust crystals

The resulting 3D crystal is much more robust than an STM-created surface. “The defects created in the interior of the crystal are protected from the environment,” Ross explains. This allows measurements of different properties in different laboratories without needing cryogenic refrigeration or vacuum.

This could also ease the path to practical application for what is, say the researchers, an emergent many-body state. “That’s where the fun stuff comes in,” Ross says. “I’m excited because of the scalability of this that allows us to look at the interactions between the defects rather than just creating a defect itself. The stability of the microscopes that allows us to keep going and create a huge array is really exciting.” The researchers are examining various possible applications in, for example, quantum simulation and the manufacturing of matter with atomic-scale precision.

The team describes its work in Nature.

“It’s a fascinating paper,” says materials scientist and STM expert Ludwig Bartels of the University of California, Riverside. “It’s definitely above the scale of what scanning tunnelling microscopy could do…and, as they discussed in their paper, it’s probably a really interesting scale in which they can think about electronic states extending between the different defects they are making.”

He says that, while he does not believe this will ever be the way computer chips are made “it is definitely an order of magnitude above what was possible before”. Moreover, he says that the ideas used in the paper to monitor the motion of the atoms remind him of those developed 30 years ago for STM. “They are not exactly the same, but they are reminiscent, and they are just as ingenious,” he says.

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In the arena of public engagement, astronomy holds one distinct advantage over other areas of physics: the ability to generate an endless supply of pretty pictures. But not all astronomers benefit equally from this superpower – when it comes to capturing the punter’s imagination, it is optical astronomy that reigns supreme. Whether it’s the latest image of the Horsehead Nebula from the Euclid telescope or Voyager’s “Pale Blue Dot” photograph, this narrow band of the electromagnetic spectrum dominates public discourse on outer space.

It is with this in mind that astrophysicist and author Emma Chapman’s latest book is especially pertinent. A love letter to long-wavelength astronomy, Radio Universe: How to Explore Space Without Leaving Earth sheds a new (non-optical) light on a powerful and often overlooked tool in science: the radio wave.

Chapman takes us on a cosmic tour, starting with planet hopping across our solar system, before diving through the spiral arms of the Milky Way to explore black holes, neutron stars and the origin of our universe. At each stop, our tour guide outlines all that radio wavelengths have taught us about these phenomena, with humour and endearing appreciation. She also highlights some of the uphill battles for recognition fought by radio astronomers over the years.

Throughout the book, Chapman effectively outlines distinct advantages of radio waves over the visible spectrum. For starters, they are unattenuated by Earth’s atmosphere and dust in the intergalactic medium. This allowed radio astronomers to see further into both space and time; and with less expensive instruments. Moreover, a radio telescope’s ability to make observations is not hampered by bad weather – indeed, they can happily continue collecting data at day or night.

As Chapman explains, many of humankind’s biggest achievements are indebted to the radio wave. When astronauts first walked on the Moon in 1969, they relied on radio communications to keep them on course, while their safe landing site had already been selected from detailed maps of the lunar surface assembled by radar (radio detection and ranging).

As we fly with Chapman through the inner solar system, some of radio’s biggest strengths are highlighted in contrast to other means of exploration. Take Venus. Scientists in the Soviet Union admirably sent wave after wave of space probes (14 in total) as part of the Venera programme (1966–1982). Each one lasted mere minutes or hours on the surface before being crushed by the hellish pressures and temperatures of the Venusian atmosphere. Meanwhile, radar facilitated far more efficient surveys of the surface by both Russian and US spacecraft in orbit around the planet.

Chapman also explains how, in 1956, radio astronomers provided the first realistic (and apocalyptic) picture of life on Venus. This was in stark contrast to the earlier infrared-based measurements, which had suggested a tranquil and potentially life-supporting environment. It was later clarified that the infrared waves originated from the top of the Venusian atmosphere, whereas the longer wavelengths of radio revealed the nightmarish conditions below.

Chapman goes on to outline in astonishing detail all that radio waves have taught us about the best places to set up camp on Mars. Radar surveys of the Red Planet have uncovered secret caverns below the surface, which will provide future colonisers with access to subterranean water deposits and shelter from high-energy solar particles. Her coverage of this topic, in particular, is a masterclass in making science engaging, with Chapman playing the role of a Martian real-estate agent – “Valles Marineris is a very up-and-coming area, don’t you know?” – and I for one think she could be up for employee of the month.

A consistent and thought-provoking theme that emerges in Radio Universe is “seeing is believing”. On several occasions in history, we find radio-based discoveries requiring confirmation with some other “more visible” means of investigation as a prerequisite for widespread acceptance by the field. For example, it was not until we saw the first waveform of a gravitational wave detected by the LIGO detectors, in 2016, that these predictions of general relativity were considered confirmed. This was despite the indirect detection of gravitational waves through radio observations of pulsars more than four decades earlier.

Chapman highlights the emotional impact on the astronomy community, and the world as a whole, of the first image of a supermassive black hole, assembled with radio interferometry and unveiled in 2019 by the Event Horizon Telescope. Even with all of the faith we as scientists place in Einstein’s theory of gravity, the photographic proof of these unimaginable phenomena still resonated. As Chapman aptly puts it, “a picture tells a thousand equations”.

The book also highlights the ideological battles fought by radio practitioners over the years, from confirming the temperature of Venus to validating the Big Bang theory itself. One can’t help but wonder if this visible-centric view of the world is to blame for the apparent “radio scepticism”. Or is just a case of new kid on the block, given that radio astronomy only began in the mid 20th century, while optical imaging dates back much further?

Whatever the reason, this optical astronomer comes away from Chapman’s latest book with a newfound respect and appreciation for the longer wavelengths. And as far as Martian real-estate ventures go, sign me up for one of the new builds on Utopia Planitia. After all, the property prices can’t be as bad as inner-city UK living, can they?

• 2026 John Murray Press £25hb 352pp

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Conventional particle accelerators use radio frequency cavities to push particles to high energies, but these machines are vast and expensive. Laser wakefield accelerators (LWFAs) offer a radically different approach. When an intense laser pulse travels through a plasma, it drives a rippling disturbance called a wakefield. Electrons can be trapped in this plasma wave and surf along it, being boosted to very high energies over just centimetres.

However, these electrons tend to outrun the plasma wave that accelerates them, a limitation known as dephasing. One proposed way around this problem is the flying focus: a laser pulse engineered so that its point of highest intensity moves along the propagation axis at a controllable velocity. By matching this velocity to that of the electrons, the plasma wakefield could, in principle, remain phase locked to the particles, enabling sustained acceleration. While the flying focus concept has been theoretically developed and experimentally demonstrated in principle in recent years, the detailed structure and behaviour of the resulting wakefields has not yet been optimised for applications.

In a new study, a team of researchers from the Weizmann Institute of Science probed these wakefields directly, combining high resolution experiments with advanced simulations. Using femtosecond relativistic electron microscopy, the team sent a separate electron beam through the flying focus wakefield, allowing them to image its electromagnetic structure with micrometre spatial resolution and femtosecond timing.

The results reveal that flying focus wakefields are stable but highly structured, blending linear and nonlinear features and extending off axis in ways not seen in conventional laser driven wakefields. The study also shows that factors such as plasma density, composition and ionisation dynamics can significantly reshape the wake. These effects must be carefully modelled and controlled if the scheme is to deliver on its promise.

By opening a direct experimental window onto flying focus wakefields, the work provides the crucial insight needed to turn a compelling idea into a practical technology.

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Quantum technologies often imagine distant users – Alice and Bob – sharing entangled particles and trying to learn something about them. In principle, the most powerful measurements are global: Alice and Bob act as if their systems were in the same lab. In reality, they are usually limited to local operations and classical communication (LOCC). This means that each makes measurements locally and sends classical messages back and forth. A long standing debate is how much classical communication is actually required to perform a given quantum task.

In a recent article, Arthur Dutra and colleagues, tackled this question by analysing quantum measurements that use just one round of classical communication. Rather than treating LOCC as an all or nothing option, the team asked more precise questions. Who should measure first? How many classical bits are needed? Does Bob really need to adapt his measurement based on Alice’s message?

Their key contribution is a new mathematical framework that turns these questions into efficiently solvable optimisation problems. Using a hierarchy of semidefinite programmes (a standard tool in quantum information theory) the authors placed tight upper bounds on what one round LOCC measurements can achieve, even when the size and direction of the classical message are fixed.

Applying this framework to the task of guessing which quantum state was prepared (quantum state discrimination) they uncovered several surprises. In some cases, it matters a lot who measures first: Bob first strategies can outperform Alice first ones, even when only one classical bit is exchanged. Perhaps most interestingly, they showed concrete examples of adaptive strategies (those in which Bob’s measurement depends on Alice’s outcome) are provably more powerful than any non adaptive approach.

Beyond these examples, the work offers a general way to quantify classical resources in quantum protocols. As future quantum networks face practical limits on latency, memory, and bandwidth, knowing exactly how many bits must be communicated, and when, may be just as important as entanglement itself.

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After more than 15 years of conflicting results, two independent measurements appear to have settled the debate over the charge radius of the proton. The new measurements, which are the most precise to date and are based on protons in normal atoms, suggest that the radius is 0.8406 femtometres (10^-15 m) – very close to the measured value that initiated the controversy back in 2010.

Charge radius is a measure of how far the electric charge of a particle extends into space. In protons, researchers have two main ways of measuring it. The first is by scattering electrons from hydrogen atoms, which consist of a single proton bound to an electron. The second is by analysing the Lamb shift, which slightly modifies the gap between energy levels of the hydrogen atom and arises from interactions between the electron and proton. According to the theory of quantum electrodynamics (QED), these interactions will be slightly different for electrons occupying different energy levels, so the resulting energy shift depends, in part, on the radius of the proton.

For many years, the accepted value of the proton radius – based on measurements by several groups around the world – was around 0.876 femtometres (fm). Then, in 2010, a team led by physicist Randolf Pohl at the Max Planck Institute of Quantum Optics (MPQ) in Garching, Germany performed a new measurement using muonic hydrogen. In this quasi-atomic system, the electron is replaced by its much heavier cousin, the muon. Muons are more tightly bound to the nucleus and therefore have a much higher probability of being very near – or indeed within – the proton. This makes their Lamb shift much more dependent on the proton’s radius.

Based on their measurement of the photon energy required to drive the 2S-2P transition in muonic hydrogen, Pohl and colleagues calculated that the proton’s radius was 0.8418 fm with an uncertainty of 0.0007 fm. This value disagreed substantially with previous measurements and was well outside the error bars of earlier results.

Physicists found this concerning because it implied that either QED theory had been misapplied or that the Standard Model of particle physics was somehow lacking. These concerns increased as subsequent measurements (on normal as well as muonic atoms) by various other groups produced some results that agreed with the 2010 finding, but also others that did not.

New measurements also yield a radius of about 0.84 fm

Both new studies involved placing hydrogen atoms in a vacuum and using laser light to control and measure transitions between different electron energy levels. In one of the studies, Thomas Udem and colleagues at MPQ measured the 2S-6P transition in atomic hydrogen with a precision 2.5 times higher than previous measurements, reaching the five sigma (5𝜎) threshold commonly used as a benchmark in the field. Thanks to this precision, they were able to test the Standard Model’s predictions to 0.7 parts per trillion (ppt) and the bound-state QED corrections to 0.5 parts per million (ppm).

The 2S-6P transition involves a single photon, which means it has fewer systematic corrections than the more commonly probed two-photon resonances. “Lower systematic corrections lower the possibility of making errors in those corrections,” notes MPQ team member Lothar Maisenbacher.

The downside is that the linewidth of the transition is very large compared to the precision the team needed to reach, but Maisenbacher says they were able to overcome this. “We succeeded in finding the centre of the resonance at 1 part in 15 000 of its width, which is (as far as we know) a world record for laser spectroscopy,” he tells Physics World.

The other work, by Dylan Yost and colleagues at the Colorado State University in the US, involved measuring three two-photon transitions (in 2S-ns, with n being between 8 and 10) that had not previously been studied for this purpose. Yost describes these transitions as “nice” because they are intrinsically narrow. “Generally speaking, narrower lines can be measured more precisely,” he explains. “This has us very excited that we may be able to really push our technique to higher precision with some modest additional technical improvements.”

The Colorado State researchers say that the three measurements they made were “very precise and agreed very well with each other”. By combining these results, they produced the most precise values for the proton radius to date based on two-photon spectroscopy, complementing the one-photon method used in the MPQ group’s 2S-6P measurement.

“Our new measurement, together with the new result from the Garching group and the muonic hydrogen measurements, are now the most precise spectroscopic measurements of the proton radius and all show extremely good agreement,” says Yost. “Personally, I find it remarkable that the theorists working on the required bound-state QED calculations have been able to make such accurate and reliable predictions and that these predictions have now been tested and show agreement at the parts-per-trillion level.”

The most precise spectroscopic measurements of the proton radius

According to Meisenbacher, the 2010 muonic result has now been thoroughly tested, and the proton radius puzzle has been resolved in a way that suggests that both the Standard Model and QED theory remain valid. “Our result also confirms that muonic spectroscopy is a powerful tool for studying nuclear properties,” he says. “Indeed, the community is working on extending it to heavier atoms.”

Both groups now want to repeat their measurements in atomic deuterium, where the nucleus contains a neutron as well as a proton. A similar discrepancy exists in this nuclear charge radius and measuring it precisely could reveal a hitherto undetected interaction between the electron and the neutron that is not included in the Standard Model.

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Almost 2000 scientists have signed an open letter criticising planned redundancies at the University of Nottingham in the UK. The signatories, which includes six Nobel laureates, call on the university to reverse its plan to reduce the number of staff members in the physics department from 71 to 51.

News of the possible job losses emerged on 12 May, when 2700 Nottingham staff were sent letters saying they were at risk of redundancy as part of plans to slash more than 600 academic posts throughout the university. The university says it is making the move because it could otherwise run out of money within the next five years.

Nottingham is a member of the “Russell Group” of 24 leading, research-intensive universities in the UK, with its school of physics and astronomy ranking seventh out of 44 UK physics departments in the most recent REF assessment. It is famous for its work on magnetic resonance imaging, through the contributions of the Nottingham Nobel-prize-winning physicist Peter Mansfield.

From the 2700 staff receiving letters, 56 are in physics and represent academic and technical staff across all levels. Antonio Padilla, a particle theorist at Nottingham, told Physics World that putting almost all members of physics staff at risk is an “act of academic sabotage”.

It takes years of dedication to build up a world-class reputation. I worry that it can be destroyed much more quickly

Antonio Padilla, University of Nottingham

“This is a school brimming with creativity and innovation,” he says. “There is excellence in all areas of physics, from particles to astronomy, from condensed matter to medical imaging. It takes years of dedication to build up a world-class reputation. I worry that it can be destroyed much more quickly.”

The open letter created by researchers at Nottingham in response to the cuts says that the proposals will cause “long-lasting damage” to what they claim is a “globally respected physics department”. It urges senior leaders at Nottingham to work with the University and College Union (UCU) to create “a more sustainable vision for physics and astronomy at the university”.

Stating that the job cuts will lead to fewer students applying to the university due a “decline in its reputation”, as well as a loss of student income, the letter has so far been signed by six physics Nobel laureates – Andre Geim, Andrea Ghez, Konstantin Novoselov, Roger Penrose, Didier Queloz and Brian Schmidt. Geim was once a postdoc at Nottingham.

“Physics underpins current and future economic developments; from AI, through quantum technologies to new medical imaging techniques,” the letter states. “Cutting the university’s strength in these areas is a short-sighted move that will deprive Nottingham students and the East Midlands of the capability to take advantage of these opportunities for growth.”

The university should exhaust every option to make the department sustainable before resorting to compulsory redundancies; shrinking it now is shortsighted

Catherine Heymans, Astronomer Royal for Scotland

Catherine Heymans, Astronomer Royal for Scotland, who has signed the letter, says that the UK needs “strong, geographically distributed physics departments” to help diversify the economy away from just a few centres. “The university should exhaust every option to make the department sustainable before resorting to compulsory redundancies; shrinking it now is shortsighted,” she says.

Those comments are echoed by Jim Wild, president of the Royal Astronomical Society, who urges Nottingham to reconsider the short-sighted cuts. “Reducing staff capacity by this magnitude will irreparably damage a world-class department, severely harming both its international reputation and its capacity to deliver high-quality education,” he says.

A ‘more careful approach’

Padilla, who is UCU representative for Nottingham’s physics and astronomy department, says that “a more careful approach” is required to protect staff at the university. He points out that the UCU has proposed an alternative financial model for the university that “doesn’t set fire to our academic reputation”.

After two decades in which the UK university sector has boomed, there are now fears that the problems at Nottingham could be replicated elsewhere. “What happens at Nottingham now matters for the rest of the sector,” adds Padilla. “This isn’t just make or break for physics at Nottingham – it matters for science everywhere in the UK and beyond.”

Philip Moriarty, another at-risk Nottingham physicist, says that the UCU offer, which he says has been “carefully considered, costed and modelled” has been “rejected, out of hand, with no justification by the university”. Senior management at the university, he adds, “have provided no evidence to support their strategy, including, in particular, their university-wide 18-22 student-staff ratio target”.

On 18 May all affected staff across the university were sent an e-mail to participate in a “supporting you during change” programme that involves two 90-minute online webinars “to help you consider the proposed changes that have been announced and to help you plan for what you may wish to do next”.

“Nauseatingly, even the provision of ‘support’ for staff during this process has been outsourced to an external consultancy company,” adds Moriarty. “Alongside the complete disregard for data and evidence, it’s the disingenuousness and dishonesty that rankle most. Their repeated claims that they care about staff are baseless.”

In a statement, a spokesperson at the University of Nottingham noted that “doing nothing is not an option” given the “significant financial challenges” the university faces.

“We know that change of this scale is not easy, and we do not underestimate what it means for many of our colleagues and students. We will be doing everything we can to support our people through the next few months,” the statement says. “These are really difficult decisions and we have not taken them lightly. It is vital that we respond to the changing sector demands to ensure we are sustainable for future generations and continue to deliver world leading teaching and research and an excellent student experience.”

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People have been using reinforced rubber for nearly a century, but we still don’t know why it’s so strong. Researchers at the University of South Florida (USF) in the US now say they may have the answer thanks to advanced molecular dynamics simulations. Their work could make it possible to design new materials that are safer and have even better mechanical properties.

Reinforced rubber is made by adding a nanoparticle filler – typically carbon black or silica – to elastic polymers (elastomers). The presence of this nanofiller explains why tyres, industrial seals and many other everyday rubber products tend to be black in colour. More importantly, the nanofiller makes the material robust to heat and able to withstand millions of cycles of deformation, meaning that objects can last for years, or even decades, without deteriorating.

One property that may play a central role in the materials’ mechanical performance is the stickiness of the nanofillers’ surfaces. This enables them to attract and immobilize nearby polymer segments, but USF engineer David Simmons, who led this new research effort, says the exact mechanism remains an enigma because it is hard to differentiate between the many physical processes that may be at play.

“I love this kind of problem,” Simmons says, adding that it combines “massive practical impact” with “a deep fundamental scientific question that has resisted resolution for so long that much of the field has moved on to different problems”.

A model that distinguishes between mechanisms

To disentangle the different processes, Simmons and his colleagues conducted molecular dynamics simulations of elastomeric nanocomposites. These simulations incorporated strong polymer-particle attractions, with the strength controlled by a parameter known as ϵ_{P F}.

The team studied how ϵ_{P F} and various other parameters, including nanoparticle filler loading ϕF and structure N_p, affected various reinforcement mechanisms by measuring several parameters. These included the nanocomposite’s bulk and Young’s moduli; the Poisson’s ratios for pristine and filled elastomers; and the time required for the nanocomposite to relax after being stretched.

The team then used this model to explore four possible ways that strong polymer-particle attractions might, hypothetically, increase mechanical strength. The first of these is called strain localization. If this was the key factor, strong attractions could immobilize the surrounding polymer, straining the remaining mobile elastomer domains. “This ‘bound-rubber’ mechanism was popular in the early literature,” Simmons notes.

The second mechanism is known as glassy bridging. The idea here is that regions of polymer between particles could vitrify, forming links that elongate the cohesive nanoparticle network.

The third mechanism is called transient crosslinking. Under this hypothesis, slower-moving or stationary polymer regions around particles, or adhesions to the particles themselves, act as long-lived physical crosslinks in the matrix. “This could increase the effective crosslink density of the rubber, thereby increasing the entropic elastic modulus of the polymer domains,” says Simmons.

The fourth and last mechanism is a Poisson’s ratio mismatch. Poisson’s ratio measures how materials change shape when stretched, and a mismatch between ratios for the rubber and the nanoparticles would essentially force rubber to “fight” against its own incompressibility.

And the winner is…

The results of the study, which is detailed in PNAS, show that while all four of these mechanisms play a role in reinforcing the nanocomposites, the most important is the Poisson’s ratio mismatch.

“This is an incredibly cool result because it tells us that the strength of nanocomposites doesn’t come from their polymer-like elasticity but from their resistance to volume expansion,” Simmons says. “This is an entirely different picture than the field has held for more than 80 years. What’s more, we’ve shown that some of the other leading proposed mechanisms from these past decades (for example, particle network percolation, sticky interactions and space-filling effects) actually contribute to this mechanism, enhancing it and making it more effective in strengthening rubber.”

The biggest barrier to obtaining these findings, Simmons adds, was that these materials are difficult to simulate at a molecular level. “They involve very large system sizes, very large timescales and very complex processing histories,” he says. He highlights the work of two lab members – postdoctoral researcher Pierre Kawak and PhD student Harshad Bhapkar – as “instrumental” in overcoming these challenges to generate “beautiful and insightful” simulations of these systems.

As for the work’s impact, Simmons tells Physics World that it could provide a new foundation for rational design of elastomeric nanocomposites with transformative mechanical properties. “Let’s take the tyre industry alone, for which it is important to design a rubber that combines good traction, durability and fuel economy,” he says. “The industry has had to very empirically navigate this space of competing properties – they call it the ‘magic triangle’. Our findings could help design this triangle with a grasp of the fundamental principles that govern reinforcement in these systems.”

The researchers are now trying to better understand how elastomeric nanocomposites ultimately fail and determine how this failure can be predicted and even delayed. Their work is supported by the Mechanical Properties and Radiation Effects programme within the US Department of Energy.

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The impact of quantum science and technology is going to be profound, with quantum computing in particular – but also quantum sensing, simulation and communication – set to be a major driver of economic growth and sustainable development in countries around the globe.

Ireland is no exception. It is already home to some of the world’s largest technology companies, many of which are heavily investing in quantum technologies. Moreover, the country’s quantum research and innovation community demonstrates a significant level of expertise in fundamental quantum science and quantum technology.

But to ensure Ireland is not only a user of quantum technologies but an active contributor to its development long into the future requires both strong partnerships with industry and public research bodies across borders, and the consistent production of people with the talent and skill to push quantum science forward.

Transferable skills across academia and industry

Founded in 1592, Ireland’s oldest university Trinity College Dublin hosts a future-focused MSc Quantum Science and Technology programme that fits this remit perfectly. The one-year master’s course is the ideal stepping stone into a career in quantum research, whether students want to advance fundamental knowledge in academia or develop the next world-leading quantum technology in industry.

“Unlike other fields, for many of the exciting positions in industry, the skills are very similar to what would be required of a PhD student,” explains quantum information theory expert Professor Felix Binder, who directs the course. “It’s a level of scientific rigour, it’s having a broad knowledge base and coding skills, it’s being confident to independently work on a project – these are what we focus on.”

This is why the course very much leans into helping students develop the fundamentals. Topics such as quantum computation, quantum information theory and open quantum systems are covered in depth. This provides the foundation for exploring more advanced and specialized topics, like quantum materials or tensor network theory.

The combination of fundamentals and highly specialized knowledge is designed to equip students with skills that are relevant for the long term, says Binder. Though he acknowledges that now is an exciting time when many quantum technologies are maturing and being commercialized, the course generally looks beyond the latest fads.

“If students are choosing quantum as their profession, realistically they’re looking at a potential 40-year career,” he says. “As this is their last part of formal lecture-based education, we want to be sure that we set them in good stead for at least many years, and not just the immediate future.”

Career insights

In addition to preparing students with the knowledge they will need, the course also exposes students to people working at the cutting-edge of the subject, providing them with an understanding of the types of careers available and contacts to build their network and take the first steps towards their chosen quantum profession.

For instance, world-leading academic and industry experts deliver a range of short mini-modules and specialist lectures. Some of these experts come from companies involved in the Trinity Quantum Alliance. “The Trinity Quantum Alliance is a unique space on campus where fundamental quantum science and research meets real-world applications,” says the Alliance’s Director Professor John Goold. “Here, multinational companies, SMEs and start-ups come together to work on projects with Trinity academics.”

The founding industry partners are Microsoft, IBM, Moody’s, Horizon Quantum Computing and Algorithmiq. Each partner shares research and regularly presents talks to faculty and students, and most have a presence on or near the Trinity campus. This arrangement offers students direct access to the people shaping the quantum revolution, as well as potential internship opportunities.

Further experts who have given guest lectures and shared their experiences are alumni. Several are completing PhDs at various universities dotted across the world, from the EU to the US and Australia. Many have gone on to become full-time researchers and even team leads in quantum companies, including Quandela, Horizon, Algorithmiq and EleQtron, as well as companies traditionally not associated with quantum technology, such as MasterCard. Others have taken positions at government labs across European countries, including a Max Planck Institute in Germany and a national research centre in the UK.

Although this alumni network may be relatively small – with the course having only been running for five years and graduating 60 students – it is extremely useful for the current cohort, showcasing the different paths potentially available to them and providing contacts who can offer support and advice on how to enter and thrive in those careers.

A quantum future for the Emerald Isle

Looking forward, Binder envisions even closer integration of the MSc degree and doctoral training into the European quantum ecosystem. This will be enabled through a new EU-wide training network: the European Quantum Academy. Trinity is one of the lead institutions of this new training academy, which was launched in May 2026. Composed of more than 70 partner institutions from across Europe, it will open new opportunities to students in Ireland in terms of industry interaction, international exchange and advanced training beyond the degree’s core modules.

In addition, there are ongoing plans for further research investment in Ireland, bringing together the different schools within Trinity, and other universities and industry players to work more closely together.

The result of these efforts should be a thriving quantum ecosystem that takes advantage of Ireland’s unique position within the EU and close ties with the US and UK to provide ever more new and varied opportunities in quantum science and technology, as Binder succinctly summarizes: “The field is young and growing – Ireland is a very exciting space for quantum right now”.

Applications for Trinity’s MSc Quantum Science and Technology are now open for the next academic year. Find out more and apply: www.tcd.ie/physics/quantumtech/

The post Quantum science in the heart of Dublin appeared first on Physics World.

There is a shape in physics that is remarkably hard to destroy. You can shake it, heat it, push it and disturb it in every way imaginable, but unless you physically tear the fabric it resides in, it will survive perfectly intact. This is not wishful thinking. It is a mathematical certainty. That shape is called a skyrmion.

The easiest way to picture a skyrmion is to imagine a dartboard covered in tiny arrows. At the very centre, every arrow points straight down into the board. At the outer edge, every arrow points straight up. In between, they rotate smoothly through every possible direction, completing a full rotation and closing back on themselves. This pattern has a score called the skyrmion number, and that score is locked at exactly ±1 (the sign simply defines which way the twist runs). Noise cannot nudge it. Heat cannot drift it. A stray disturbance cannot flip it. The only way to change it is to violently rip the whole pattern apart.

Scientists first found skyrmions hiding inside certain magnetic materials and immediately recognized them as dream candidates for carrying information (a skyrmion present means 1, a skyrmion absent means 0, and nothing in the environment can accidentally corrupt it). But magnetic materials are slow and confined to a chip. The next natural question was bold: what if you could take this indestructible shape and put it inside light itself, travelling freely through open space?

A team of researchers from Tianjin University in China, together with collaborators at Nanyang Technological University in Singapore and Oklahoma State University in the US, has now done exactly that – and gone one step further. As described in Optica, the researchers created not just one skyrmion in light, but two completely different kinds, and found a way to switch between them at will using nothing more than the rotation of a single thin optical half-wave plate.

The two types are an electric skyrmion, where the topological twist lives in the electric field of the light wave, and a magnetic skyrmion, where the same twist lives in the magnetic field. And they are as distinct from each other as a left-handed knot is from a right-handed one.

To generate these skyrmions, project leader Jiaguang Han and colleagues built a flat chip roughly the size of a small stamp, its surface packed with thousands of tiny C-shaped gold antennas, each one far smaller than a bacterium. When a structured laser beam hits this chip, the antennas absorb the incoming near-infrared light and re-radiate it as terahertz waves.

The key is how the antennas are arranged on the chip: one set is laid out in concentric rings pointing outward, while another set spirals around the centre like the spokes of a wheel. Each arrangement, when activated by the right kind of laser beam, generates a different skyrmion-carrying light pulse. Switching the laser from one beam shape to the other is done by rotating a single optical plate by just 45°, which flips the chip from producing one skyrmion type to the other, instantly and cleanly.

“The core innovation lies in the nonlinear metasurface that converts shaped near-infrared femtosecond laser pulses into tailored terahertz toroidal light pulses,” explains first author Li Niu in a press statement.

The team confirmed this process by mapping the full three-dimensional structure of each light pulse at multiple positions in space and time. The skyrmion numbers they measured came out at –0.990 and +0.992 for electric skyrmions, and –0.991 and +0.994 for magnetic skyrmions, within 1% of the mathematically perfect value of ±1. The tiny deviation from a perfect score of ±1 is simply down to the limits of any real measurement – sampling a fleeting pulse of light in three dimensions will always leave a small rounding error. However, the topology itself remains exactly intact.

The importance of this result reaches far beyond the elegance of the experiment. The next wave of wireless communication technology – already being designed to operate at terahertz frequencies, which can carry vastly more data than current mobile networks – has a serious enemy: the real world. Humidity, atmospheric turbulence, buildings and even rain can scramble a terahertz signal in ways that are very hard to protect against.

Conventional optical signals encode information in the brightness or precise timing of a wave, but both of those are fragile; noise corrupts them the same way that a smudge ruins ink on paper. A skyrmion signal is fundamentally different. The information is encoded in the topological shape of the light pulse, and that shape cannot be accidentally altered by the environment. It is protected not by better engineering or thicker shielding, but by mathematics itself.

On top of that, having two switchable skyrmion states, electric and magnetic, effectively enables two distinct channels of information to travel along the same beam, doubling the capacity without using any extra bandwidth.

What this team has built is a proof of concept for a new kind of communication: one where the message is written in a shape that the universe, by its own rules, refuses to erase.

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Analysis by physicists in China suggest that if dark matter carries even a tiny electric charge, it will generate a magnetic “hum” in Earth’s geomagnetic field. And what is more, data from existing magnetometer networks can already constrain this effect.

Dark matter is one of the biggest open questions in modern physics. Astronomers infer the existence of hypothetical dark-matter particles from their gravitational influence. The invisible presence of dark matter explains why galaxies rotate too rapidly for their visible mass, for example. Also, the gravitational lensing of starlight suggests a similar invisible mass in galaxy clusters. Yet the exact nature of dark matter particles remains unknown.

Ariel Arza at Nanjing Normal University and colleagues have explored what happens if dark matter carries a tiny electric charge, far smaller than that of an electron. The charge would be so small that dark matter would still be effectively “invisible” to most particle-physics experiments. However, the researchers argue that Earth’s own magnetic environment could turn our planet into a huge dark-matter detector.

Millicharged dark matter

This idea of millicharged dark matter (mDM) appears in several extensions of the Standard Model of particle physics, especially where the visible sector and a hidden dark sector mix slightly. In such models, dark matter can acquire a minuscule effective coupling to electromagnetism. Not enough to behave like ordinary charged matter, but enough to open new detection channels.

In a recent study described in Physical Review Letters , Arza and colleagues focused on bosonic mDM in the ultralight regime. This regime is particularly interesting because ultralight dark matter would behave collectively like a coherent wave, which makes its signal easier to model and search for in frequency space. This wave picture predicts a nearly monochromatic signal at a frequency tied directly to the dark-matter mass.

Earth as a dark matter detector

If dark matter has an extremely tiny electric charge and behaves like an oscillating field, it can act like a weak source that drives a small alternating current. In Earth’s magnetic field, that current would create an extra magnetic signal, a faint, repeating “hum” added to the usual geomagnetic field. This hum should appear at a specific, well-defined frequency set by the dark-matter mass, rather than being spread across many frequencies like most natural magnetic noise. In the mass range for this study, the signal is predicted to get stronger for lighter dark matter (roughly scaling like 1/m², where m is the dark-matter particle mass).

At the very low frequencies expected for ultralight millicharged dark matter, the electromagnetic fields change slowly, almost like steady magnetic fields with a small repeating wobble added on top. The ground acts like a conducting boundary below and the ionosphere acts like another conducting boundary above, so together they shape how these low-frequency magnetic signals travel and spread. Instead of needing to build a special resonant chamber in a lab, the “detector” is the space around Earth itself.

Testing with real data

The researchers predict that mDM would result in a narrow, single-frequency signal in Earth’s magnetic field. The frequency of the signal is determined by the dark-matter mass and the signal’s amplitude defined by dark matter’s tiny electric charge.

Azra and colleagues looked for this signal in real magnetometer data. They used null (no-signal) results from two major efforts: SuperMAG, which combines geomagnetic measurements from stations around the world, and SNIPE Hunt, which searches magnetometer data for narrow, single-frequency signals that could indicate new physics. Since neither dataset shows the persistent monochromatic oscillation expected from ultralight mDM, they used this absence of a signal to set upper limits on how large the dark matter’s tiny electric charge could be, for particle masses roughly in the range 10⁻¹⁸–10⁻¹⁴ eV/c².

Constraining mDM has already been done using astrophysical observations – for example, looking for the effect of mDM on how stars lose energy. However, these bounds often rely on complex environments and modelling assumptions. This latest study demonstrates that Earth-based magnetometer data can be just as powerful. Indeed, the ultralight mass range the researchers find limits that exceed stellar-cooling constraints by more than 13 orders of magnitude in some cases.

Modelling choices

Because the team’s argument relies on modelling choices (like boundary conditions and simplifying limits), one might question how sensitive the results are to these choices. Team member Jing Shu  at Peking University in China, tells Physics World that the final calculation is not limited to the small-parameter approximation. “Our calculation is valid across the full parameter space of ε and κ, not only in the ε, κ ≪ 1 regime.” Here, ε is the dark matter charge, and κ is its electromagnetic coupling. He explains that the small-ε, small-κ discussion is mainly there to give a clearer physical picture.

The researchers also note an important limitation: if the dark matter’s tiny charge is still “too large,” Earth’s magnetic field can deflect it enough that the signal no longer keeps increasing and instead levels off. Related to this, Shu explains that the result does depend on ionospheric conductivity because it helps set the boundary conditions of the Earth’s ionosphere cavity. “Variations in conductivity, for example due to solar activity effectively modify this boundary and therefore change the geometric factors that determine the signal amplitude. In practice, this leads to variations that can be on the order of unity in the predicted signal.”

Finally, Shu says the next step is to make the search more targeted and coordinated. “A natural next step is to carry out dedicated measurements in electromagnetically quiet environments, for example in remote field sites across different locations in China, and to build a coordinated network of magnetometers.” This would help distinguish a global, coherent signal from local noise and improve sensitivity to weak oscillations.

The post Earth’s magnetic field could be ‘ringing’ with dark matter appeared first on Physics World.

Alfred Tennyson was “the only poet since the time of Lucretius who has taken the trouble to understand the work and tendency of the men of science” said the English biologist Thomas Huxley on the occasion of Tennyson’s burial in the Poets’ Corner of Westminster Abbey on 12 October 1892. Tennyson’s acquaintance with science and its impact on his poetry is the subject of historian and broadcaster Richard Holmes’s new book The Boundless Deep: Young Tennyson, Science and the Crisis of Belief.

Born in 1809 – the same year as Charles Darwin – Tennyson matured at a time when science was transforming ideas about the universe. “It was stranger and vaster than previously thought,” writes Holmes, “and yet more vulnerable and paradoxically, more temporary. There were no Biblical eternities anymore.”

As a teenager Tennyson looked through telescopes and microscopes, and read books on physics, chemistry, botany and astronomy. In notebooks he interspersed poetic verses with careful observations of plants, birds, animals and other natural phenomena. In one poem he imagined himself on the Moon’s surface, in another as a microscopic creature. His verses expressed both wonder and suspicion. “O suns and spheres and stars … are you realities or semblances?” wrote the 14-year-old poet.

An unbreakable bond

While studying at the University of Cambridge, Tennyson met Arthur H Hallam and the two became inseparable, sharing interests in nature, poetry and science. In 1833 they spent a “science week” in London, visiting the new London Zoo in Regent’s Park, the Gallery of Practical Science in Piccadilly, and displays of magnets, microscopes and steam cannons.

That year several books on astronomy appeared, including one by Tennyson’s Cambridge tutor William Whewell, who coined the term “scientist”. The publications acquainted readers, including Tennyson and Hallam, with newly discovered star systems and “the nature of their formation, their growth over immense and previously inconceivable periods of time, and finally their slow but inevitable extinction”, as Holmes describes. “These ideas of so-called deep time and deep space were gradually transforming the whole notion of the material universe.”

That autumn, at age 22, Hallam unexpectedly died from a brain haemorrhage. It was the most traumatic event of Tennyson’s life, “a particular extinction from which he never recovered”, writes Holmes. Tennyson spent nearly two decades coping by writing In Memoriam A H H, published in 1850. In several sections near the poem’s midpoint, Tennyson seems to invoke nature as a possible source of solace in imagery that has challenged scholars ever since.

“Every evolutionist can cite the line,” wrote the evolutionary biologist Stephen J Gould in his 1995 book Dinosaur in a Haystack. “We would draw and quarter any imposter who couldn’t.” Gould was referring to the line “Nature red in tooth and claw”, a phrase from In Memoriam that many scholars think anticipates Darwinian evolution and consoled Tennyson. But Gould instead finds that the line only reflects the biological and geological catastrophism of Tennyson’s time and adds that Tennyson knew it held no comfort. “Science cannot tell us why a man should die so young,” Gould writes, “or how a grieving lover should resolve his suffering.”

Holmes gives a more nuanced interpretation, saying that Tennyson did not grieve and then seek solace in science. Rather, Tennyson’s grief began with his awareness that scientific truths prevented him from turning to religion; that the “death of an individual”, as Holmes writes, “counted for nothing within the vast and pitiless scale of geological death and extinction”. Tennyson’s grief sprang from his experience of a conflict between science and religion, which put him in a “state of hovering, or trembling, between science and religion, between empirical evidence and traditional faith”.

Life, poetry and science

Holmes has spent his career writing about Romantic poets and their world. For example, one of his previous books was The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science. Holmes’s vast command of the era shows in his ability to identify the people from whom Tennyson learned what he knew.

He introduces us to Jane Marcet, an innovative scholar and writer whose books about physics and chemistry inspired not only Tennyson but also embarked the geologist Charles Lyell and physicist Michael Faraday on their scientific careers. Marcet would have been elected to the Royal Society, Holmes writes, “except for the slight hindrance that no female Fellow was admitted until 1921”. (Marcet’s husband, a Swiss doctor, made it in.) Meanwhile, the mathematician Mary Somerville – said to be “one of the only six persons in England who understands Laplace” – was a polymath whose books acquainted Tennyson with the entire spectrum of hard sciences.

Science, Holmes shows, is not a privileged knowledge that poets must bow before, nor a set of facts to accept or deny. Rather, its constant development reshapes our experience of the world as much as families and friendships, mentors and myths. The Boundless Deep is as instructive about the science found in Tennyson’s poetry as it is about science in human experience.

• 2025 William Collins 448 pp; £25.00 hb; £14.99 ebook

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While LiMn_xFe_1-xPO₄ (LMFP) cathode materials have been investigated academically for decades, they have been adopted by dominant battery manufacturers only in the past three years. What has prompted this sudden commercial interest? What market share might LMFP gain, can it outpace LFP and NMC? What are the outstanding limitations, and how might these be overcome?

In this webinar, we aim to answer these questions, covering challenges ranging from the fundamental characteristics of LMFP to large-format cell manufacture and industry trends. We will also showcase recent research carried out at WMG to better understand LMFP behaviour and how AI can be used to design improved LMFP electrode microstructures to enable fast charging.

Join this webinar to find out how this emerging material may alter the EV and battery manufacturing landscape.

Gerard Bree is an assistant professor in the battery materials and cells (BMAC) research group at WMG at the University of Warwick, where he carries out research to better understand how lithium-ion battery performance can be improved so that batteries provide more energy over a longer lifetime at a lower cost. He is interested in the interaction between academia and the battery industry and works on many projects supporting companies to build a battery supply chain in Europe. Bree received his undergraduate degree from Trinity College Dublin and his PhD from the University of Limerick.

The post Is LMFP the next big thing for EV batteries? appeared first on Physics World.

A single atom is one of the last places one would expect to find a gravitational wave. These ripples in spacetime are caused by movements of massive objects such as black holes, and they are typically detected using instruments that measure tiny changes in the distance between mirrors separated by kilometres.  Their home territory is on large scales, not the microscopic scale of an atom.

Despite this, physicists have questioned for decades whether gravitational waves might affect how often atoms spontaneously emit photons. Previous theoretical studies suggested that the answer was no: the total spontaneous emission rate of a single atom remains unchanged, so the atom appears unaffected by the wave.

This null result is not surprising. Gravitational waves stretch space in one direction while squeezing it in a perpendicular direction. Detectors such as LIGO measure this effect by sending light between mirrors in perpendicular “arms” and comparing how long the light takes to travel along each arm. For a single atom, there is no comparable separation to measure, so scientists did not expect that passing gravitational waves could be detected this way.

A hidden signal

In a new study, published in Physical Review Letters, Navdeep Arya and collaborators at Stockholm University in Sweden and Eberhard Karls Universität Tübingen in Germany identified a loophole in this argument. Although gravitational waves do not leave an imprint in the number of photons emitted, Arya and colleagues calculated that they do affect how those photons are distributed in angle and frequency.

This distinction is crucial. Because a gravitational wave does not make the atom emit more or fewer photons overall, its effects will cancel out if one only measures the total number of photons. However, if the photons are sorted by their direction and frequency, a characteristic pattern emerges that reflects the wave’s stretch-and-squeeze geometry. Depending on the wave’s frequency, this pattern can manifest either as a small shift in the emitted photon frequencies or as additional sidebands in the spectrum.

The reason this is possible, Arya explains, is that the atom isn’t the only thing the gravitational wave interacts with. “It’s actually the atom and the [quantum] field,” he says. Because the field is a global object, he adds, it can carry information about the gravitational wave even when the atom itself does not.

Beyond counting photons

The existence of these effects opens a new way of thinking about gravitational-wave detection. Instead of watching how spacetime changes the distance between mirrors, a next-generation detector might look for how a passing wave changes the light emitted by atoms. This approach would make it possible to detect lower-frequency gravitational waves, which are difficult to reach with ground-based detectors such as LIGO.

A system that could detect these effects experimentally would look very different from a traditional gravitational-wave detector. Instead of measuring how a passing wave changes the distance between mirrors, one would need to excite a large cloud of atoms, collect the photons they emit through spontaneous emission, and resolve the angles and frequencies of those photons.

Though this is not a standard experiment, parts of the required technology already exist. Cold-atom experiments, for example, routinely trap and control millions of atoms. The challenge is to combine these capabilities with sufficiently precise measurements of the directions and frequencies of the emitted photons, while also controlling technical noise.

The researchers say their next step is to understand whether the signal will survive under realistic experimental conditions. According to Jerzy Paczos, the Stockholm PhD student who led the study, the most important task will be to consider the full range of technical noise that would appear in a real experiment, determine which noise sources matter most, and conclude from that whether their proposal is truly feasible. The researchers are also interested in whether cavities or collective effects in atomic arrays could amplify the signal.

For now, the work suggests that gravitational waves may leave traces in a place that physicists have not fully looked before: not in how fast an atom emits light, but in the detailed pattern of the light it gives off. In doing so, it points to a new way of using quantum systems to probe spacetime itself.

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Researchers in the US and Canda have discovered a naturally occurring “Voronoi pattern” in the Chinese money plant.

Voronoi diagrams were introduced in the 1600s by French philosopher René Descartes and are named after the Russian mathematician Georgy Voronoi, who defined and studied them in the early 1900s.

Voronoi diagrams are geometric patterns used to divide space into regions. The plane is divided up into tessellating polygons, known as cells, that each contain a “seed” point. Every location inside a cell is closer to its seed than any other seed in a neighbouring cell.

Voronoi patterns have numerous applications across mathematics, as well as in various other disciplines such as modelling animal territories, city planning or crystal growth.

Voronoi-like patterns are common in nature, such as giraffe stripes. However, the difference between textbook Voronoi patterns and what we see in nature is that the latter usually lacks visible seed points.

Now, Saket Navlakha from Cold Spring Harbor Laboratory in New York and colleagues have found an exception in Pilea peperomioides, the Chinese money plant.

Chinese money plants are perennials native to China’s Yunnan and Sichuan provinces. The plant has round, flat leaves that feature prominent pores called hydathodes. These points are then surrounded by looping reticulate veins that transport water and nutrients to and from the leaf.

By mapping the pores and veins, the team discovered a naturally occurring, visible, Voronoi pattern with the veins acting as the cell boundaries and the pores being the seed points. They then built a mathematical model to match the observed patterns.

“To our knowledge, this is the first demonstration of the occurrence of Voronoi diagrams in plant venation patterns, where both edges and centres are visible and functional,” they write.

The researchers now plan to use the model to understand why other plants that have similar vein structures do not stick to the Voronoi structure in the same way as the Chinese money plant.

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Researchers in China have developed a new way of probing the magnetic domains within altermagnetic materials and used it to study a prominent altermagnet candidate, alpha-phase iron oxide. According to their measurements, this material shares certain properties with ferromagnets despite having a near-zero net magnetization – a fact the researchers say supports its classification as an altermagnet.

In most magnetically ordered materials, the spins of atoms (that is, their magnetic moments) can either line up parallel with each other or antiparallel, alternating up and down. These arrangements are driven by spin-exchange interactions between the atoms, and they lead to ferromagnetism and antiferromagnetism, respectively.

Altermagnets, which were identified as a distinct class of magnets in 2022, behave differently. While their neighbouring spins are antiparallel, like an antiferromagnet, the atoms hosting these antiparallel spins are related to each other by rotational or mirror symmetries rather than the spatial inversion and half-lattice translation symmetries found in conventional antiferromagnets, explain physicists Luyi Yang and Wanjun Jiang of Tsinghua University, Beijing, who led this study. This unique property leads to a zero net magnetization in altermagnets while still allowing for the spin-split electronic band structures typically found in ferromagnets.

An altermagnet candidate

Alpha-phase iron oxide (α-Fe₂O₃) is a naturally occurring mineral commonly known as haematite. It was long believed to be an antiferromagnet, but recent theoretical research has suggested that it should be relabelled as an altermagnet.

To shed more light on the nature of α-Fe₂O₃, the team turned to a phenomenon known as the giant magneto-optical Kerr effect (giant MOKE). Named after the Scottish physicist John Kerr, who discovered it in 1877, it occurs when linearly polarized light reflects off the surface of a magnet. Interactions between the light and the material’s magnetic domains cause the polarization vector of the light to rotate, and the direction of rotation can be reversed by reversing the direction of magnetization. The effect therefore provides a “window” into materials’ magnetization states, enabling scientists to monitor and characterize them.

The Tsinghua University researchers say they found evidence of a connection between the material’s MOKE responses and its Néel vector, which is a parameter that defines its so-called staggered magnetic order. In altermagnets, the orientation of this Néel vector determines the material’s magnetic space group, which in turn dictates whether magneto-optical responses are allowed or not, they explain.

“By using magnetic fields to switch the Néel vector through a tiny canted magnetization in α-Fe₂O₃, we selectively measured the symmetry-permitted MOKE signals and confirmed the absence of symmetry-forbidden components on different surface orientations of α-Fe₂O₃ single crystals,” they say.

The researchers also observed that at large applied magnetic fields, the MOKE signals remain constant. This finding further rules out contributions from canted magnetization, which should increase with the field. These experiments therefore strengthen the idea that the MOKE signal they measured is truly driven by the Néel vector and the corresponding symmetry of α-Fe₂O₃.

Broadening methods for imaging altermagnetic domains

To date, most experimental studies on altermagnets have focused on spin transport. Yang, Jiang and colleagues say that they turned to MOKE-based measurements because they would like to study insulating altermagnets, for which electrical transport measurements are inaccessible. “We aimed to uncover the symmetry requirements for magneto-optical responses and broaden the methods for imaging altermagnetic domains,” they explain.

The main challenge they encountered was proving that the MOKE they observed predominantly originates from the Néel vector, rather than from the canted weak magnetization. The researchers say they addressed this through symmetry analysis, first-principles calculations and performing the experiment in different configurations to show that the Kerr signal remains nearly constant even as the canted magnetization keeps increasing at large applied magnetic fields. “By examining such effects on single crystals with different surface orientations, we confirmed that different Néel vector orientations produce distinct MOKE responses, which are consistent with the symmetry of magnetic space group predicted by theory,” they tell Physics World.

The researchers say their work shows that MOKE responses are not limited to ferromagnets, as is conventionally understood. Provided the symmetry requirements are satisfied, altermagnets can also exhibit giant MOKE. “We have shown that standard MOKE imaging microscopy can be used to visualize altermagnetic domains and domain walls in α-Fe₂O₃,” they say. “This could accelerate the development of altermagnetic spintronics based on these structures, with potential applications in advanced memory and logic devices.”

The researchers now plan to extend their approach to other altermagnetic insulators and metals and to use the magneto-optical response to study the (presumably) ultrafast dynamics of domain walls. Their present study is detailed in Chinese Physics Letters.

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This episode of the Physics World Weekly podcast features an interview with Paul Howarth, who became president of the Institute of Physics (IOP) in February.

The IOP is the professional body and learned society for physics in the UK and Ireland. Representing 21,000 members, it supports physicists at all stages of their careers and seeks to make physics accessible to people from all backgrounds.

With a PhD in nuclear physics, Howarth has had a long career in the nuclear sector working on the European Fusion Programme and at British Nuclear Fuels, as well as co-founding the Dalton Nuclear Institute at the University of Manchester and serving as chief executive officer of the National Nuclear Laboratory.

He talks to Physics World’s Michael Banks about his career in nuclear energy and his priorities now as president of the IOP. These include improving physics education and raising the profile of physics and physicists across society.

Howarth also voices concerns about recent funding cuts to particle physics, astronomy and space science in the UK, saying it could hamper the flow of students into the subject, with a potential impact on burgeoning areas such as quantum tech.

• The Institute of Physics owns IOP Publishing, which brings you Physics World.

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Signs of an exotic atom-like system made up of a neutral meson bound to an atomic nucleus via the strong interaction have emerged in experimental data from two international collaborations. If confirmed, this hitherto unobserved system could shed light on the origins of hadron masses and provide new insights into the fundamental symmetries of quantum chromodynamics in nuclear matter.

The strong interaction is one of the four fundamental forces of nature, alongside gravity, electromagnetism and the weak interaction. It is responsible for binding quarks into hadrons, which are three-quark particles such as protons and neutrons, and for holding protons and neutrons together within atomic nuclei. Electrically neutral mesons – short-lived particles made up of a quark and an antiquark – are likewise subject to the strong interaction, which can bind them to atomic nuclei in a way that is conceptually similar to an electron bound to a nucleus by the electromagnetic force.

Studying these meson-based nuclear systems is important because it helps us better understand the properties of the strong interaction, says study co-leader Yoshiki Tanaka of RIKEN in Japan. The eta prime meson, η′, is particularly interesting, Tanaka adds, because its relatively large mass cannot be explained by a simple quark model. “This U(1) problem, as it known, was raised as long ago as the 1970s by the physicist Steven Weinberg,” he notes.

Direct experimental access to the 𝜂′-meson mass in nuclei

Modern theories attribute the η′ meson’s large mass to the presence of chiral symmetry breaking in quantum chromodynamics, which is the fundamental theory of the strong force. These theories predict that this mass should be reduced in a nuclear system, and this is what Tanaka and colleagues set out to test.

“Spectroscopy studies of 𝜂′-mesic nuclei provide direct experimental access to the 𝜂′-meson mass in nuclei and offer a unique opportunity to investigate the underlying mechanisms of how the mass of hadrons comes about,” he explains.

In the team’s study, a beam of protons strikes a ¹²C atomic nucleus at near-relativistic speeds and removes a neutron from it. This neutron, together with a proton, forms a deuteron that propagates away in a forward direction, leaving behind a nucleus of ¹¹C in a highly energetic state. It is this excess energy that gives rise to an 𝜂′-meson.

In rare cases, the researchers explain, the meson then binds to the ¹¹C nucleus, forming an 𝜂′-mesic nuclear system. But because these events are so rare, they are hard to find. “One of the major challenges we encountered in the work was the very large amount of background events we registered during our measurements,” Tanaka recalls. “These were about 100 to 1000 times higher than the signal events.”

The researchers overcame this problem by developing a new experiment that allows them to efficiently select signal events associated with the formation of 𝜂′-mesic nuclei by “tagging” the particles they decay into. This enabled them to measure not only the forward-travelling deuteron, but also the decay products of the short-lived 𝜂′-mesic nuclear state.

The researchers say that their results, which they describe in Physical Review Letters, indicate that the 𝜂′-meson mass drops by about 60 MeV in nuclear matter. “This result qualitatively supports the theoretical scenario [that attributes] the origin of the 𝜂′-meson mass to chiral symmetry breaking together with the dynamics of gluons (massless particles that mediate the strong nuclear force) in general,” Tanaka says.

Members of the team, which also includes researchers from the η-PRiME Collaboration and the Super Fragment Separator Experiment Collaboration, together with physicists from Justus Liebig University Giessen in Germany with their working groups GSI/FAIR, say they are now planning follow-up experiments to confirm that they have indeed observed 𝜂′-mesic nuclei. “We also aim to increase the significance to the 5σ level, which is required to firmly establish the discovery on new quantum states in particle and nuclear physics,” Tanaka says.

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There are two difficulty settings: choose between a 96-piece jigsaw and the 48-piece version.

Image courtesy: NASA

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The prestigious Cavendish Laboratory at the University of Cambridge in the UK has an iconic status in the history of science.

The university’s physics department was initially based in central Cambridge. It is where Francis Crick and James Watson famously worked on the double-helix structure of the DNA molecule.

Yet in 1974 – 100 years after its foundation – the Cavendish moved to a new home on the outskirts of the city.

The building was built in a drab style, covered in grey-brown pebble dash, and featured a maze of interconnected blocks. It was home to generations of physicists, and many thousands of students over the last 50 years.

But the outdated and crammed structure is no longer deemed fit for use and in October last year the lab moved to the nearby larger, brighter and airy purpose-built Ray Dolby Centre. The new centre has been designed to encourage meetings and exchanges with a single entrance, common foyer and centralized café, which are also open to the public.

The move to the Dolby Centre took almost a year to complete, during which time about 180 truckloads moved 3000 m³ of research equipment, crates and furniture belonging to the lab’s 31 research teams.

This included specialized equipment such as 47 cryostats, 98 optical tables, various molecular beam epitaxy set-ups as well a teaching laboratory and museum collection, which includes the model of DNA created by Watson and Crick as well as the cathode ray tube that was used to discover the electron.

Pending chemical and asbestos decontamination, the old building will now be demolished by third-party contractors.

Once complete, the site will host a cycle route until plans are developed for the future use of the site.

Physics World visited the old building in February and this article presents a selection of images from the site.

The post Final look inside the Cavendish lab’s 50-year home before demolition appeared first on Physics World.

Photonic crystal slabs are periodic structures that confine light in two dimensions while allowing it to leak in the third. Their in‑plane periodicity forces light to behave like an electron in a crystal, forming bands rather than isolated modes.

These objects can host an array of novel physical phenomena, from ultra‑sharp resonances to exotic singularities such as exceptional points. Among the most intriguing are bound states in the continuum (BICs). These are modes that, despite lying in an energy range where radiation is allowed, remain perfectly confined.

In a new theoretical study, a team of researchers from China showed that this leakage, and its surprising absence in certain cases, can be understood from a single first‑principles viewpoint. Central to their approach are Bloch waves and the scattering matrix.

Bloch waves are the natural building blocks of waves in periodic structures. Instead of spreading freely, light inside a photonic crystal is organised into Bloch waves whose fields repeat from one unit cell to the next, up to a phase factor. Even in an open slab, only a small number of these Bloch waves propagate across the thickness and carry energy towards the surrounding medium.

The scattering matrix describes how incoming waves are converted into outgoing ones by the periodic structure. The values of frequency where the matrix becomes singular (its poles) correspond to resonant modes. For open systems, these frequencies are complex: the real part sets the resonance position, while the imaginary part measures how fast energy leaks away.

One key insight of this work is that the complexity of the problem collapses dramatically once the analysis is restricted to the minimal set of Bloch waves that actually propagate. Interference between just two waves can already explain “accidental” bound states in the continuum (BICs), where radiation vanishes despite the mode lying in an open channel. Including three waves naturally produces Friedrich–Wintgen and symmetry‑protected BICs near band crossings. Adding polarisation reveals far‑field vortices and exceptional points.

By grounding resonant photonics in a minimal scattering‑matrix picture, the authors unify a wide range of phenomena within a single, transparent framework. This should prove valuable for designing efficient resonators, lasers, and topological photonic devices.

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Ferroelectric materials have a permanent electric dipole, an internal separation of the centres of positive and negative ionic lattices, that can be flipped by applying an electric field. They also undergo a structural change at a material dependent temperature. known as the Curie temperature, above which this dipole behaviour disappears. Despite having permanent dipoles, ferroelectrics are insulating materials. These properties make them valuable in technologies such as sensors, actuators, and memory devices. 

In this work, the researchers study the band gaps of ferroelectric materials to better enable their use in energy conversion, catalysis, and optoelectronic devices, where understanding light absorption and electron behaviour is essential. Traditionally, the band gap in ferroelectrics has been treated as a single number. However, ferroelectrics are not conventional semiconductors. They contain localized charges, polarons, internal dipoles, and structural disorder. These features give rise to three distinct band gaps, not one. 

There is the intrinsic fundamental band gap, defined as the ground state difference between the fully occupied valence band and the completely empty conduction band. The smaller optical gap is associated with light induced transitions involving bound electron-hole pairs (excitons), and the even smaller transport gap associated with electrical conduction via localised electronic carriers. 

In this study, the authors determine the fundamental, optical, and transport gaps using X‑ray photoelectron spectroscopy, optical spectroscopy, and electrical conductivity measurements, respectively, for NBT‑6BT and NaNbO₃. The fundamental gap values are further supported by DFT calculations. Because these three gaps differ by about 1 eV or more, different experiments have actually been probing different gaps all along, meaning past optical and electrical results were often compared incorrectly, leading to widespread misinterpretation. The conclusion establishes that ferroelectrics possess three fundamentally different energy gaps, explains why they differ, provides a framework for measuring them, confirms their values theoretically, and highlights why this distinction is crucial for designing future energy and electronic technologies. 

Do you want to learn more about this topic?

Prospects and applications near ferroelectric quantum phase transitions: a key issues review by P Chandra, G G Lonzarich, S E Rowley and J F Scott (2017)

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Tests of fundamental physics that were previously impossible could become a reality thanks to a new way of producing extremely intense beams of light. Using a state-of-the-art high-power laser, researchers at the University of Oxford, UK demonstrated that they could dramatically increase the efficiency of a nonlinear optical technique called relativistic harmonic generation. According to the team, this increase could herald a paradigm shift, making it possible to achieve hitherto unheard-of electromagnetic field intensities in the laboratory.

The theory of quantum electrodynamics (QED) predicts that at very high intensities, light can interact with the vacuum, converting light energy directly into matter. “If we can achieve such intensities, we could test theories about the fundamental nature of the universe,” says Robin Timmis, who led the new study. “However, doing so requires a laser system a million times more intense than those currently available.”

Relativistic harmonic generation

In the new work, Timmis and her colleagues in Peter Norreys’ group at Oxford used the Gemini laser at the UK Science and Technology Facilities Council’s Central Laser Facility (CLF) to generate coherent extreme ultraviolet (XUV) and X-ray photons via relativistic harmonic generation. They began by firing high-frequency, ultrashort, sub-picosecond (10^-12 s) laser pulses onto a solid glass target. This creates a plasma that acts like an oscillating mirror, and Timmis likens the next step to shining a flashlight at this mirror while it is rushing towards you at near-light speed – a concept known as “Einstein’s flying mirror”. The result is that the light reflected from the plasma becomes compressed, and gains intensity.

Working with researchers from Brendan Dromey‘s group at Queen’s University Belfast in Northern Ireland, the team used a process called coherent harmonic focus to concentrate this light into a region as small as a few nanometres across. This step may have boosted the light beam’s intensities as high as 10²³ W cm⁻², although Timmis acknowledges that this is an estimate based on previous theoretical simulations, as the team was unable to measure it directly.

“If confirmed with further experiments at Gemini, or indeed even larger facilities, we may have made the most intense source of coherent light ever,” says Timmis, who received this year’s Institute of Physics Culham Thesis Prize in part thanks to this work, which is described in Nature. “The energy in our XUV beam was over three orders of magnitude brighter than previous measurements,” she adds. “By resolving a long-standing gap between theoretical expectations and experimental results, we confirmed the required energies to support a coherent harmonic focus and therefore offer a substantial boost in intensity above that of the original laser pulse.”

Towards the next generation of extreme electromagnetic field studies

According to the researchers, these results demonstrate that there is a realistic experimental pathway to next-generation laboratory studies of extreme electromagnetic fields. In particular, they say that the quantum critical field for QED tests, which is known as the Schwinger limit and has a value of >10¹⁶ V cm⁻¹ or >10²⁹ W cm⁻², is now open, paving the way towards all-optical studies of the quantum vacuum. As well as fundamental physics, Timmis says that more efficient harmonic generation could also have applications in ultrafast imaging of physical and biological systems, photolithography and fusion science.

The Oxford team is now analysing data from a follow-on experiment at the CLF that will guide their next steps. “We will be shortly publishing results about a new harmonic beam that we have discovered on that run,” reveals Timmis, “and future studies will focus on actively controlling the coherent harmonic focus and directly measuring its intensity.”

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Researchers at Stanford University in the US have found a way to generate light deep within living tissues, potentially leading to new forms of gene and cancer therapies. The proof-of-concept approach uses ultrasound to trigger luminescence in nanoscale particles travelling through the bloodstream, and it has already been tested in tissue-mimicking “phantoms” and live mice. However, its developers caution that human trials are still some way off.

Light has numerous applications in medicine and biological research. It is widely used, for example, to stimulate cell growth and in photodynamic therapies for skin and eye conditions, as well as certain types of cancer.

The problem is that many potentially useful wavelengths of light are easily scattered by tissues and become attenuated over relatively short distances. This means they cannot penetrate very far into the body without help from invasive methods such as removing overlying tissue or inserting/injecting optical implants and light-emitting nanoparticles into the target area.

Sound and light

The new work by Stanford materials scientist and engineer Guosong Hong and colleagues involves nanoparticles made from a ceramic material with the chemical formula Sr₄Al₁₄O₂₅:Eu,Dy. This material is mechanoluminescent, meaning that it emits light when subjected to mechanical stresses and deformations. In Sr₄Al₁₄O₂₅:Eu,Dy, these mechanoluminescent effects can be induced by exposing the material to sound waves, which penetrate more deeply into tissue than light waves.

The Stanford researchers began by coating their nanoparticles with a biocompatible film. They then suspended the particles in a solution and injected the resulting colloid into the veins of mice. Thanks to the rodents’ vascular systems, the particles soon travelled to all parts of their bodies.

The researchers then showed they could make the nanoparticles emit blue light with a wavelength of 490 nm simultaneously in multiple locations (such as the brain, gut, hindlimb and spine) by applying sound waves to different parts of the mouse’s body. In addition, they showed they could create precise patterns of in-situ light generation throughout the three-dimensional volume of the animal, controlled over distances of 100 to 200-μm in the focal region. The ultrasound can also be used as a scanner to define where the light is generated.

A host of applications

The team picked the 490 nm wavelength because it has many applications, including neuron modulation and photodynamic cancer therapy. However, applying the same technique to different materials could produce other useful wavelengths, too. Indeed, Hong and his colleagues are exploring the possibility of using materials that emit ultraviolet light, which has antiviral and antibacterial properties.

The researchers say their approach is broadly applicable to virtually all therapeutic modalities that requires light to be delivered deep within the body, including optogenetics, phototherapy and photo-switchable gene editing. This last technique currently suffers from off-target effects, but the researchers say that by pairing light-producing nanoparticles with a light-activated gene-editing system, they may be able to use ultrasound to turn gene editing on and off in localized areas of the body.

“The overarching theme of my lab’s research is to develop new strategies to deliver and receive light throughout the body in its native, living state,” Hong tells Physics World. “In 2024, we reported on a method to render living tissue transparent using strongly absorbing dye molecules. In the present study we have taken a complementary approach: rather than modifying how light propagates through tissue, we leverage the intrinsic penetrative capability of ultrasound, together with the pervasive reach of the circulatory system, to generate light directly within deep regions of the body.”

Reporting their work in Nature Materials, the researchers are now working to integrate their approach with other light-activatable control systems, including photo-switchable Cas9 gene editing in collaboration with Michael Lin’s lab at Stanford. In parallel, they hope to develop alternative mechanoluminescent materials that will break down safely in the body. While the materials studied in this work did not seem to show adverse effects in mice, they also did not break down quickly, and the researchers say they could accumulate in organs such as the liver.

“What we’re demonstrating here is a proof-of-concept showing that you can produce light emission in a programmable manner deep within the body,” Hong says. “If we can replace the material with one that is safer to be used in humans, that will start to pave the way for clinical applications.”

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Quantum technologies are undoubtedly going to have a large impact on our world, potentially revolutionizing everything from healthcare and the environment, boosting the economy and helping with large-scale optimization challenges. But for them to deliver on these many promises, it will be vital for many countries to train and build a quantum-ready workforce.

There are four pillars to the quantum sector – quantum computing; quantum simulation; quantum communication; and quantum sensing and metrology. But in each case there is a lack of trained individuals who can take on jobs across the board. Indeed, statistics in both the UK and the US suggest there is only one qualified worker for every three quantum jobs. With governments continuing to invest lots of money into national quantum programmes; a growing number of new quantum start-ups being launched; and ever more multi-national firms zoning in on quantum, the shortage of those with the right skills to work across the sector is expanding.

The Colorado School of Mines in the US is now trying to remedy this situation by launching the country’s first bachelor-level quantum systems engineering degree programme, due to start this autumn. An undergraduate degree specializing in quantum and systems engineering might, at first glance, seem odd. But 2021–2023 data from the Chicago Quantum Exchange show that 55% of quantum tech jobs only require a BSc or two-year associate degree. For instance, roles that ask for just a BSc include systems assembly and maintenance, measurement engineers, technical sales and marketing.

“Industry demand especially values engineers with a systems-level understanding of quantum devices, and there is also a need for quantum technicians who can build and maintain quantum hardware,” says Frédéric Sarazin, director of the quantum programme at Colorado School of Mines. As the first standalone bachelor’s degree in quantum systems engineering in the US, the programme is designed specifically to supply industry-ready graduates.

The main focus for Sarazin and colleagues was to bring into the programme key aspects of systems engineering – which involves understanding and overseeing all aspects of a complex system, from its inception through to practical production, and even managing the final product. The goal: to help companies get their products and technologies out of the lab and into the marketplace. Rather than focusing on isolated components, systems engineers are trained to understand how complex technologies behave as integrated entities.

“A quantum computer, for example, is more than just its qubits,” says Sarazin. “It’s cryogenics, optics, electronics, control software, signal processing and the user interface, all interacting with each other.” Companies are keen to hire people who can understand and help develop their quantum product as an end-to-end system, bridging the gap between the physics and engineering aspects, as well as making sure the end product is robust, scalable and manufacturable.

The physics may be what Sarazin calls the “secret sauce” – but turning it into a device that is reliable, manufacturable and maintainable is an engineering problem “with a quantum flavour to it”. “What companies want is people who understand the product as a system, from beginning to end,” Sarazin explains.

Quantum hotspot

Colorado, in America’s mid-west, is a quantum innovation hotspot, with quantum companies employing more than 3000 people across the state. To develop the new programme, Sarazin and colleagues carried out an extensive consultation process with companies, institutions and organizations that all look to hire quantum engineers, to get a clear idea of the skills that students should have at the end of their course. They also collaborated with Elevate Quantum – a consortium of 120 organizations advancing quantum workforce development and commercialization in Colorado, New Mexico and Wyoming – to design an interdisciplinary course that will integrate physics, electrical and mechanical engineering, computer science and engineering design.

While the students will learn plenty of foundational quantum physics, they won’t cover the full curriculum of a traditional physics degree. “You’d be talking about a six-year degree if we covered everything,” says Sarazin. Certain advanced topics, such as quantum error correction, remain overwhelmingly in the domain of PhD-level jobs and so are deliberately excluded.

The lab is meant to be a signature experience. It’s where students start interacting with industry in a meaningful way

A key feature of this degree will be hands-on practical engineering experience in the lab. Plans are under way to build a dedicated quantum device laboratory for the students, allowing companies to bring in their tech and partner with the on-campus facilities. “The lab is meant to be a signature experience,” says Sarazin. “It’s where students start interacting with industry in a meaningful way.”

That connection is reinforced through internships and a year-long design project in the final year, with project topics supplied directly by quantum companies. “The junior-to-senior year is when internships really matter,” explains Sarazin. “That’s often what leads directly to a job.”

Future prospects

Although the programme is firmly industry-focused and aims to get graduates straight into the job market, students can progress to the Colorado School of Mines’ existing master’s programme in quantum engineering, launched in 2020. “At the bachelor’s level, you’re building breadth,” says Sarazin. “If students want to specialize further, they absolutely can.”

Many of the skills that the students will develop – from electronics and embedded systems to control software and algorithms – are highly transferable too. “Looking beyond the quantum sector, our systems engineering students will have acquired a set of skills that is highly applicable in other industries,” says Sarazin.

The first cohort will likely be around 15–20 students this year. Looking ahead, Sarazin has a clear benchmark for success: “a near-100% placement in industry at the end of the degree – that’s what we’re aiming for”.

Beyond that, success will mean continuously refining the programme in response to industry feedback. “This isn’t static,” Sarazin says. “If companies tell us something needs adjusting, we want to respond.” For students still hesitant to take the leap into a specialized BSc or the quantum sector, Sarazin’s message is clear: quantum careers are here to stay and the direct path into the industry is starting earlier than ever before.

The post Building up the quantum workforce: an undergraduate route into industry appeared first on Physics World.

The amount of oxygen that a heart consumes is a key indicator of its health. If the heart is not receiving or using enough oxygen, heart tissue can be damaged, contributing to future heart failure.

With abnormal myocardial oxygen consumption an indicator of potential cardiac dysfunction, its measurement could help in the early detection and treatment of heart failure. And as one in four individuals are likely to develop heart failure in their lifetime, this is of critical importance. But measurement of myocardial oxygen consumption is not a simple process. The gold standard for determining the heart’s oxygen use is cardiac catheterization. But this test – which involves threading a catheter from a patient’s neck or groin into the coronary sinus (CS), the largest coronary vein – is highly invasive, time-consuming and comes with a level of risk.

A new MRI technique may soon offer a rapid, non-invasive alternative. Developed by an international research team headed up at Cedars-Sinai Health Sciences University, the high-resolution MRI method can assess the heart’s oxygen consumption in just three minutes. In an initial study of 22 patients with heart failure, reported in Science Translational Medicine, the team validated its accuracy, feasibility, performance and repeatability.

MRI is sensitive to blood oxygenation via the blood oxygen level–dependent (BOLD) signal, originally developed for mapping brain activity. Use in the heart remains challenging, however, due to the need for complex calibration, motion sensitivity and long acquisition times. Hsin-Jung Yang, of the Biomedical Imaging Research Institute at Cedars-Sinai, and collaborators overcame these obstacles by developing a rapid, self-calibrated cardiac MRI framework that enables free-breathing blood oximetry (measurement of blood oxygen saturation) in the CS and quantification of whole-heart myocardial oxygen extraction, without requiring contrast agents or pharmaceutical stress.

The researchers’ primary objective was to determine the accuracy and precision of MRI-derived measurements of CS blood oxygenation, compared with those obtained by invasive CS catheterization. They also aimed to perform non-invasive quantification of global myocardial oxygen consumption and myocardial oxygen efficiency, with comparisons between healthy controls and patients with heart failure.

To achieve this, they developed a motion-resolved reconstruction algorithm for cardiac BOLD MRI that enables clear imaging of the moving heart during breathing and heartbeats. The team first validated the method in pigs, and then applied it to a group of 22 patients with heart failure and a history of previous heart attack, as well as 11 healthy volunteers.

The researchers acquired clinical cine images to define the cardiac anatomy, localize the CS and measure ventricular function for estimating the oxygen–mechanical work coupling efficiency. Using this approach, they identified impaired myocardial oxygen consumption in the patient group, including those with preserved ejection fraction (how much blood the left ventricle pumps out with each contraction, a low value of which can indicate a heart problem). The finding that impaired oxygen consumption was measurable even before detectable structural or functional decline may facilitate the early detection of cardiac dysfunction.

The researchers note that their self-calibrated MRI framework directly addresses the difficulty of performing quantitative oximetry of the CS – a mobile blood vessel that undergoes marked displacement throughout the cardiac cycle. “Our framework directly addresses these challenges with a continuous, free-breathing, motion-resolved 3D acquisition that retrospectively sorts data across cardiac and respiratory phases, ensuring stable CS tracking despite its complex motion and size variation,” they write.

By eliminating the dependence on gating and calibration, the method could be applied across diverse clinical populations, including those with arrhythmias, intolerance of breath-holding or physiologic stress, for whom conventional gated acquisitions are unreliable. The team suggests that the framework also holds promise for extending oxygen consumption imaging to other moving organs, such as the liver and kidney, and that in the future, the motion-resolved BOLD framework could be applied to tissue-based quantification.

The researchers are performing ongoing clinical studies to evaluate the MRI technique in aortic stenosis (narrowing of the aortic valve) and hypertrophic cardiomyopathy (thickening of the heart muscle), where altered oxygen extraction and metabolic efficiency have revealed disease severity, risk and treatment response beyond conventional imaging.

More broadly, the Yang Lab is extending this approach to characterize oxygen utilization in all cardiometabolic diseases and associated emergent therapies, with the goal of noninvasively defining myocardial energetic supply–demand balance, identifying therapy–response phenotypes, and monitoring disease progression and metabolic remodelling over time.

“By enabling a fast, non-contrast, non-ionizing radioactive method for measuring cardiac oxygen metabolism, [this MRI method] can unlock frontiers for early diagnosis, personalized therapy, and the development of next-generation cardiometabolic treatments to combat the global heart failure epidemic,” the team concludes.

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A vast complex of steel beams for a next-generation neutrino detector has begun its descent underground in what officials have called a “pivotal phase” towards construction of the $3.3bn Deep Underground Neutrino Experiment-Long-Baseline Neutrino Facility (DUNE-LBNF).

An event was held yesterday – attended by senior officials including CERN director-general Mark Thomson and Dario Gil, undersecretary for science at the US Department of Energy (DOE) – to commemorate the start of moving 4.5 million kilograms of steel beams underground that will be used to hold DUNE’s detectors in place.

In February 2024, excavation work finished on two huge underground spaces for DUNE. Located 1.6 km underground at the Sanford Underground Research Facility in South Dakota and are some 150 m long and seven storeys tall, the spaces will be used to house DUNE’s four neutrino detector tanks that are each filled with 17,000 tonnes of liquid argon and cooled to 88 K.

When complete in 2031, DUNE-LBNF will study the properties of neutrinos in unprecedented detail, as well as the differences in behaviour between neutrinos and antineutrinos.

DUNE will measure the neutrinos that are generated by Fermilab’s accelerator complex, which lies around 1300 km away just outside Chicago.

The cryostat materials, which have been contributed by the CERN, are now scheduled to be moved underground and installed in the next few months.

“Today represents the start of a pivotal phase for DUNE, the development of the far detector structures in South Dakota,” noted Fermilab director Norbert Holtkamp. “Our focus remains on safety, quality and schedule — in that order — to ensure we successfully deliver on behalf of the US Department of Energy, our nation and the world.”

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Physicists have determined the mass of the W boson with the highest precision yet by analysing more than a billion proton collision events at CERN’s Large Hadron Collider (LHC). The new result confirms a prediction from the Standard Model of particle physics while refuting a comparably precise measurement made by Fermilab’s CDF Collaboration in 2022. This is significant because the older measurement, which used data from the defunct Tevatron collider, differed from the Standard Model’s predictions by seven standard deviations, suggesting that the W boson might be far heavier than the model allows.

The W boson is one of two elementary particles that acts as a carrier for the weak force (the other is the Z boson). As one of the four fundamental forces in nature, the weak force is what allows protons to change into neutrons (and vice versa), making it the driving factor behind radioactive decay and nuclear fusion. Precise measurements of the W and Z boson basses are therefore important for understanding these processes as well as for testing the Standard Model.

While physicists have measured the mass of the Z boson to an extremely high precision of 22 ppm (or 2.0 MeV), measuring the mass of the W boson with the same exactitude has proven more difficult. The main hurdle is that the W boson cannot easily be detected in colliders such as the LHC because it decays almost instantly. Scientists can look for its decay products instead, but that, too, is awkward. In one important channel, for example, it decays into a neutrino and a muon – and neutrinos are even more elusive than W bosons.

A fading mystery

In the new work, CERN’s Compact Muon Solenoid (CMS) Collaboration studied more than a billion proton collision events produced at the LHC in 2016. Amongst these, they identified 100 million as producing a W boson that decayed into a neutrino and a muon.

By analysing these events and simulating all the possible scenarios that could produce them, they measured the mass of the W boson to be 80360.2 ± 9.9 MeV. This is significantly less than the CDF Collaboration’s measurement, but it agrees with other previous experiments. Importantly, it also lies within the range the Standard Model predicts, leaving the CDF result – the most precise measurement before this one – looking like an outlier.

“If you take the CDF measurement at face value, you would say there must be new physics beyond the Standard Model,” says Christoph Paus, a physicist at the Massachusetts Institute of Technology (MIT) in the US and one of the lead investigators of the CMS Collaboration. “And of course, that was the big mystery.”

Now that the new, even more precise measurement agrees well with predicted values for the W boson mass, that mystery is fading, Paus tells Physics World.

Some physicists may find this disappointing. However, study lead author Kenneth Long, who was a senior postdoc in MIT’s Laboratory for Nuclear Science at the time and has since moved to a research position in Lyon, France, says the new result is “just a huge relief to be honest” and “a strong confirmation that we can trust the Standard Model”.

A starting point for precision measurements

To obtain their result, the CMS researchers needed to measure the momentum of the muon and use it to infer the W boson’s mass. This is possible for two reasons. The first is that in the W’s rest frame, its decay energy is shared roughly equally between its two daughter particles (the muon and the neutrino). The second is that muons are charged leptons, and the strong magnetic field inside the CMS detector makes them travel in a path whose curvature is a function of their momentum.

“The momentum is different to the mass, of course, but is strongly correlated with it,” explains Paus. “The challenge is therefore to track the path of the muon and every possible interaction it could have with other particles and its surroundings to estimate a value for its initial momentum.”

The CMS experiment had long planned on doing such a measurement, but it took a while to set up. Now that the measurement is complete, Paus, whose MIT group joined the W boson mass analysis effort in earnest at the end of 2020, describes it as an important starting point for the collaboration. He explains that the result proves it’s possible to measure the W boson in what he calls a “high pile-up environment”, meaning one where many proton-proton collisions overlap in a single recording, without using the Z boson mass as a calibration (as was previously done in analyses at hadron colliders). “It has put the CMS experiment finally on the map for an electroweak precision measurement of this kind,” he says.

The CMS researchers are now collaborating with experimentalist colleagues at CERN’s ATLAS and LHCb detectors, as well as their theorist partners, in hopes of setting a new standard in electroweak precision physics. Their measurement is published in Nature.

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Nuclear fusion powers the Sun, and scientists and engineers have long been trying to harness the process to generate clean energy. While much progress has been made, the commercially-viable generation of fusion energy remains elusive.

One important challenge is developing a range of specialized materials that can contain an extremely hot, radiation-emitting plasma in close proximity to ultracold superconducting magnets.

Our guest this week is Jacob John of the UK Atomic Energy Authority, who studies how radiation damages materials. In conversation with Physics World’s Matin Durrani, he talks about the near-oxymoronic materials requirements for fusion reactors and how they can be met.

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How did you get on?

16 words Warming up nicely

24 words Getting hot, hot, hot

30 words Top dog!

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After 54 years, numerous failed starts and countless abandoned dreams, earlier this year humanity finally returned to the Moon in an epic 10-day flight that gripped the planet. The Artemis II mission and its four astronauts – mission commander Reid Wiseman, pilot Victor Glover and mission specialists Christina Koch and Jeremy Hansen – gave us something to smile about during a dark time of global geopolitical turmoil.

The primary objective of the mission was to fly a crew around the Moon, to demonstrate and test the systems needed to support astronauts in deep-space exploration. In doing so, Wiseman, Glover, Koch and Hansen ventured farther from our planet than any human has ever gone and saw things on the lunar surface that no human eye has seen before.

That the crew did not land and walk on the Moon did not diminish the enthusiasm for the mission. Through today’s online world, the astronauts were able to share their own excitement with the millions watching from Earth with such relatability that the popularity of the mission was cemented in the history books.

Moreover, their voyage and safe return has paved the way for future Artemis missions. These will not only see astronauts set foot on the lunar surface for the first time since 1972, but also include building a permanently crewed outpost at the lunar south pole.

The astronauts of Artemis II

The Artemis II crew broke records by travelling further from Earth than any humans had before. But they also made history by including the first person of colour, the first woman and the first Canadian to go beyond low Earth orbit, and to travel around the Moon. Here’s who they are:

Reid Wiseman – mission commander

A former US Navy fighter pilot and test pilot, Wiseman was selected as an astronaut by NASA in 2009 and flew to the International Space Station (ISS) in 2014 as part of Expedition 41, where he took part in space walks. He was chief of the Astronaut Office between 2020 and 2022 before being made mission commander on Artemis II. A crater on the Moon seen by the crew of Artemis II has been named after his late wife, Carroll.

Victor Glover – pilot

Having joined NASA’s astronaut corps in 2013, Glover’s first venture into space was as pilot on the first post-certification flight of SpaceX’s Crew Dragon capsule to the ISS. As part of Expeditions 64 and 65, Glover performed four space walks during his time on the station. Like Wiseman, he is also a former US Navy pilot and test pilot.

Christina Koch – mission specialist

In 2019 Koch spent 326 days onboard the ISS as part of Expeditions 59, 60 and 61, setting the record for the longest continuous spaceflight for a female astronaut. During this time she also participated in the first all-female spacewalk. Prior to being chosen as an astronaut in 2013, Koch worked as an electrical engineer at NASA’s Goddard Space Flight Center, and spent time in Antarctica at the Amundsen-Scott South Pole Station and Palmer Station.

Jeremy Hansen – mission specialist

A colonel in the Royal Canadian Air Force, Hansen became an astronaut for the Canadian Space Agency in 2009. His training included taking part in the European Space Agency’s CAVES programme – spending time living underground in Sardinia – and NASA’s NEEMO 19 seven-day undersea mission. Artemis II was Hansen’s first flight into space.

The journey begins

On 1 April 2026 spectators on the ground, millions online and even the crew of the International Space Station (ISS) watched as Artemis II blasted off from pad 39B at the Kennedy Space Center in Florida at 6.35 p.m. EDT.

At launch, the four crew members were safely enclosed in their home for the next 10 days – the Orion spacecraft they had named Integrity. In turn, Integrity sat atop NASA’s gigantic Space Launch System (SLS), a rocket more powerful than the mighty Saturn V. Standing 98 m tall, the SLS was driven by four RS-25 liquid propellant engines and supported by two solid-rocket boosters, producing in excess of 39,000 kN of thrust at lift-off.

It was only the second flight of the SLS following 2022’s Artemis I, an uncrewed Moon-orbiting mission to test the SLS rocket and Orion spacecraft. Yet the Artemis II launch was flawless, with the thunderous roar deafening spectators and astounding the assorted news media present.

As the rocket left the atmosphere, the solid-rocket boosters, protective panels and launch abort system (there in case of ascent emergencies) were all successfully jettisoned, followed by the core stage of the SLS. Next, using the interim cryogenic propulsion stage (ICPS) or upper stage – fuelled by a liquid hydrogen/oxygen mix and powered by a single RL10 engine providing 110 kN of thrust – the mission performed a series of manoeuvres to raise its altitude, reaching an orbital elevation of 74,000 km.

Following that, the upper stage was separated; but before leaving it (and Earth) behind, the astronauts used it as part of their demonstration tests, which included showing they could manually pilot Integrity. While in high orbit, the mission also deployed four cubesats – one each from Argentina, Germany, Saudi Arabia and South Korea – designed to study the effects of space radiation from the Sun and in Earth’s Van Allen radiation belts, and how electrical systems perform in such radiation-drenched environments.

With all that done, it was time to leave Earth’s orbit. On day two, the engine of the service module (constructed by the European Space Agency (ESA)) performed the trans-lunar injection burn – firing for almost six minutes to propel the capsule and crew out of Earth orbit and towards the Moon. Artemis II would not orbit the Moon, but swing around it and head back to Earth, following a flight path known as a free-return trajectory. This means that after the trans-lunar injection burn, Integrity coasted for four days through space with only occasional minor course corrections to keep the Moon dead ahead. No further engine burns were required in order to get home (hence “free”) – their trajectory used lunar gravity to naturally slingshot them around the Moon while Earth’s gravity drew them back home. On a diagram, Integrity’s trajectory looks like a figure 8, which follows gravitational gradients between the Earth and the Moon.

Close encounter

On 6 April the mission flew round the Moon just once, giving the crew a seven-hour fly-by observation period of both the near and far sides.

The astronauts’ view of the lunar surface was “amazing” in the words of mission commander Wiseman. “The four of us have looked at the Moon our entire lives and the way we are responding to what we’re seeing out the window is just like we’re a bunch of kids up here. We cannot get enough of this,” he radioed back to Earth.

For much of the fly-by, the four astronauts were like space paparazzi, taking it in turns to photograph the Moon. Although lunar science wasn’t part of the mission, they had a list of 35 targets to find and record that had been selected by the Artemis II science team led by Kelsey Young from NASA’s Goddard Space Flight Center. Among them were impact craters with radial streaks of ejecta that can help planetary scientists understand how craters evolve over time; and a bright swirly feature known as Reiner Gamma that contains a magnetic anomaly and is a possible future landing site for robotic explorers.

The astronauts also targeted parts of the far side that had never before been seen by human eyes because they had been in darkness during the Apollo missions. They were aided in their efforts by a custom-designed app, called the Lunar Targeting Plan, which contained information on the targets, what features to look out for, and how to correctly photograph them – there were even prompts for discussions about what they were seeing.

Some have suggested that the crew’s efforts were more about aesthetics than science, since the entirety of the Moon has previously been mapped by past missions. These include Japan’s Kaguya orbiter, the spacecraft in India’s Chandrayaan programme and Europe’s SMART-1 mission back in 2003. Indeed, none have mapped the Moon as comprehensively as NASA’s Lunar Reconnaissance Orbiter (LRO), which launched in 2009 and to this day continues to map the entire lunar surface to 100-metre resolution, and in some places reaches an unprecedented half-metre resolution.

However, Amanda Hendrix, who is director of the Planetary Science Institute (PSI) in Arizona and who works on LRO, disagrees that lunar science wasn’t a part of the Artemis II mission.

“I think there was science to do on the fly-by,” she says. While LRO’s cameras catch a lot on the lunar surface, particularly how features seem to change with the shortening and lengthening of shadows throughout the lunar day, there’s something very crucial that is missing. “LRO’s instrumentation is limited,” explains Hendrix. “Its cameras don’t have that many filters, so we don’t get that much colour information.”

As it turns out, the Moon isn’t just a boring silver-grey sphere, but a world of many subtle colours, which Apollo 17 astronaut and geologist Harrison Schmitt discovered in 1972, when he found orange regolith made of volcanic beads rich in titanium.

“What the Artemis II crew brought is the spectral coverage that they could see with their eyes that we don’t have with LRO,” says Hendrix. “Plus, we could hear the astronauts talking about how impressed they were with the change in lighting geometry as the spacecraft went around behind the Moon, and how the day/night terminator moved across the surface. So I do think there is new scientific information there.”

The far side

Most of the science targets were found on the far side, including the mighty Orientale impact basin, which is located on the limb of the Moon as seen from Earth. (The limb is what we call the edge of the Moon when we look at it in the sky, but we can’t call it an edge since the Moon, as a sphere, doesn’t have an edge. Features on the limb are foreshortened because of perspective as the lunar surface curves away from us.) Thought to be the youngest of the Moon’s large impacts, Orientale features a lunar sea (known as a mare) at its centre, and a stunning double-ring structure at its edge. The exterior ring has a diameter of 930 km, making it one of the largest impact sites in the entire solar system.

“What really struck me is that this was the first time that humans themselves saw so much of the Moon and I think a lot of people don’t really appreciate that,” says Jeffrey Andrews-Hanna, a planetary scientist at the University of Arizona’s Lunar and Planetary Laboratory. “A great example is the Orientale impact basin. We have an incredible amount of data from orbiting robotic spacecraft, but humans had never actually laid eyes on so much of it until now. The Artemis II astronauts had a prime view looking on the surface and seeing the basin in its entirety.”

At one point shortly after the closest approach – which saw the astronauts get to within 6545 km of the lunar surface – they witnessed the Sun spectacularly fall into total eclipse behind the Moon. Then, as Integrity was cast into the Moon’s shadow, the crew saw five remarkable events – flashes of light as meteorites slammed into the surface, gouging out small new craters. The flashes were so fast that the crew were unable to catch them on camera, but they knew to be on the lookout for them nevertheless.

Lunar impacts have been sporadically witnessed before by spacecraft and amateur astrophotographers, but this was the first time it has been possible to ascertain the rate of impacts occurring on the Moon.

“To have seen five of them during that short time frame tells you the rate at which they must be happening all over the Moon, whether you can see them or not,” says Hendrix. “That’s important for telling us how much material is still out there impacting not only the Moon but also Earth, or at least the top of our atmosphere.”

Looking to future Artemis missions that will land on the Moon (currently planned from 2028), Andrews-Hanna sees a way in which the study of meteorite impacts can be enhanced by seismometers placed on the surface. “Understanding the impact flux is important,” he says. “And there’s a lot that can come from linking an impact that is seen with the seismic waves that are measured.”

A seismometer can give some indication of the size of the impacts, providing information about the mass of the meteorites impacting the Moon as well as their frequency. The seismic waves can even be used as probes into the Moon’s interior structure.

Back to Earth

The farthest that Integrity got from Earth was 406,771 km, breaking Apollo 13’s distance record of 401,171 km. While behind the Moon, the crew were out of contact with Earth for 40 minutes (as planned), far from home and completely alone.

That perfect isolation would not last long, and soon Integrity was embarking on the journey home, to arrive on Friday 10 April. Yet even if NASA and the Artemis II crew didn’t show it, there was some nervousness ahead of that return.

During Artemis I the heat shield on the empty Orion capsule suffered serious damage, cracking to the point that large chunks of the heat-resistant Avcoat material ripped dangerously away in temperatures of 2760 °C while plummeting through Earth’s atmosphere. Upon investigation, NASA scientists found that the problem was triggered by the skip guidance entry technique they had used to return Orion to Earth, which involves dipping the capsule in and out of the atmosphere so that atmospheric drag helps slow the re-entry.

In ground tests to simulate the technique, the scientists had used heating rates that had allowed a permeable char layer to form and ablate, releasing gases produced by the Avcoat layer. But in reality, dipping in and out of the atmosphere resulted in less severe heating and slower char formation. Gases accumulated in the Avcoat layer and could not escape, causing cracking.

Obviously, something needed to be changed for Artemis II. Rather than modify the heat shield that had already been built, NASA decided to change the re-entry profile. Integrity’s trajectory was made steeper, reducing time spent in the part of the atmosphere where Artemis I had problems – however, this would make it the fastest atmospheric entry ever attempted by a crewed spacecraft.

During the 13-minute fall from the sky, the heat shield held up well, staying hot long enough to release the gases. Eleven parachutes in total were deployed, slowing the capsule from 40,230 km/h while 120 km above the Earth, to 523 km/h at 8 km altitude. By the time the main parachute unfurled, Integrity was gently drifting down at less than 32 km/h for a successful splashdown in the Pacific Ocean near San Diego.

From II to V

Artemis II was a success, proving that we can send humans back to the vicinity of the Moon. Artemis III was originally planned to finally land on the lunar surface again, but it has now been repurposed for practising docking and rendezvous procedures in low Earth orbit, just as Apollo 9 did following Apollo 8’s triumphant flight around the Moon. Artemis IV, planned for early 2028, is currently the mission that will land, and hopefully later that year Artemis V will begin construction of a lunar outpost at the South Pole–Aitken Basin, among permanently shadowed craters that harbour water-ice.

After Artemis II, landing on the Moon doesn’t feel as far away as it did

After Artemis II, landing on the Moon doesn’t feel as far away as it did. Certainly, Wiseman is more optimistic now than he ever was. “I’m going to eat these words, but [landing on the Moon] is not the leap I thought it was,” he told journalists at a media conference in Houston a week after splashdown. “Once we were around the Moon in a vehicle that was handling great, if you’d given us the keys to a lander, we would have taken it down and landed on the Moon. It’s going to be extremely technically challenging, but it is absolutely doable, and doable soon.”

Visiting our orbiting companion

The first crewed mission to the Moon took place in December 1968 when NASA’s Apollo 8 entered lunar orbit. Over the next four years, the US sent another eight crewed spacecraft, including the historic Apollo 11 mission that saw Neil Armstrong take humanity’s first steps on the Moon.

But we then stopped sending people to our rocky satellite. The Apollo missions were cancelled due to budget costs and changing political priorities, while the Soviet Union’s efforts to land cosmonauts on the Moon stalled on the launchpad with the failure to develop their N1 heavy lift rocket. Many uncrewed missions from around the world have impacted, orbited, flown by or landed on the Moon, but – until now – none have had human passengers, leaving Gene Cernan as the last person to set foot on the Moon on 13 December 1972 as part of the Apollo 17 mission.

While science was not the priority for Artemis II, the scientific community is already positioning itself to make the most of returning to the Moon. Hendrix points out that three researchers from PSI have been selected as participating scientists for Artemis IV. Meanwhile, tangential to the Artemis programme is the Commercial Lunar Payload Services (CLPS), in which NASA is working with private contractors to build small landers that can take scientific experiments to the Moon. Although their success in landing has been somewhat mixed so far, it opens the Moon up to a wider range of scientists.

That’s important, says Hendrix, because there’s less grant money coming from NASA, which has seen its budget remain more or less the same while shouldering the burden of more large-scale missions.

“There is concern in the planetary science community that opportunities have been shrinking and it is because the budget hasn’t increased enough over the past couple of decades to accommodate all the programmes that are happening,” says Hendrix. There is also great uncertainty in the US science community around funding and budget changes under the current administration. “Planetary scientists can at least do some science on the Artemis missions as part of the landing science team, and they can be part of the science teams for instruments on CLPS missions, and those are the bulk of the opportunities now.”

The US is not the only country with its sights set on the Moon. China is also hoping to send astronauts – or taikonauts – by 2030. They will travel in the Mengzhou seven-person spacecraft, which is currently scheduled to do its first orbital uncrewed test flight in September 2026. The corresponding lunar lander, called Lanyue, is also under development. In the meantime, China has been sending regular robotic missions to both the near and far side of the Moon, and has brought precious lunar samples back to Earth. These missions have involved some – albeit limited – international co-operation, particularly with European scientists who have had experiments flown on the missions.

Inspiring the world from the Moon

Since the safe return of the Artemis II crew, the reaction has been as philosophical as it has been admiring of the technical feats of the mission. This was especially notable during the astronauts’ press conference, in which they discussed not the sights they had seen, but the way the mission had brought the whole world together in support.

“When we came home, we were shocked by the global outpouring of support, of pride, of ownership of this mission,” admitted Wiseman. “The four of us wanted to go out and do something that would bring the world together.”

Public interest is vital if the Artemis programme is to continue being funded, explains Hendrix. “The whole of planet Earth was brought along with them, as we watched on our screens,” she says. “Getting everybody on Earth behind these missions is important, especially the people who make the budget.”

When Apollo 8 took three astronauts around the Moon for the first time during Christmas week of 1968, it brought the American public together during a time of national strife because of the Vietnam War. The famous “Earthrise” photograph taken during the mission also became a rallying cry for the burgeoning environmental movement.

The global circumstances around the time of Artemis II’s launch were not dissimilar, with wars in South-West Asia and Ukraine continuing against a backdrop of impending environmental disaster and social and political strife. Perhaps our return to the Moon will help bring people back on Earth together once again.

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A new analysis of data from the IceCube Neutrino Observatory suggests that the energy spectrum of cosmic neutrinos is more complex than was previously thought. Whereas a previous study found that the energies of these ubiquitous, nearly massless particles follow a simple power law distribution, the latest analysis reveals a knee-like bend in the spectrum at around 30 TeV. The discovery could help astrophysicists better understand where cosmic neutrinos come from and what objects and processes in the universe are producing them.

Neutrinos are subatomic particles that are around a million times less massive than electrons. They are known to come in (at least) three different “flavours” – electron, muon and tau – but they have no electrical charge, and they interact with matter only rarely, via the weak nuclear force and gravity. This means they can travel vast distances through the universe without being deflected by magnetic fields or absorbed by interstellar material along the way.

Astrophysicists think cosmic neutrinos are produced in collisions between high-energy cosmic rays and other particles. Since cosmic rays are accelerated by a range of astrophysical sources – including gamma-ray bursts, active galactic nuclei powered by supermassive black holes, and other extreme cosmic processes – the neutrino spectrum is a way of gleaning information about where these sources are and how they work.

The catch is that because neutrinos interact so weakly, they must be studied using detectors with a very large volume. For this reason, neutrino scientists often use natural structures such as deep water or expanses of ice to support their detectors. These locations also have the advantage of being shielded from muons, cosmic rays and other sources of background noise.

Measuring neutrinos since 2010

The 5000 optical sensors that make up the IceCube observatory are suspended within a cubic kilometre of Antarctic ice. They are designed to detect the telltale flashes of visible and ultraviolet light that occur whenever a neutrino interacts with a molecule of ice. During these rare detection events, the neutrino either leaves behind an elongated track or produces a “cascade” in which its energy is contained in a small, spherical volume inside the ice.

IceCube’s detectors have been operating since 2010 and the earliest data they produced suggested that the energies of the detected neutrinos followed a single falling power law distribution. Researchers were initially pleased with this result because it agreed with simple models that related cosmic neutrinos to cosmic rays, says Aswathi Balagopal V, a postdoctoral researcher at the University of Wisconsin, US, and a member of the IceCube collaboration. These models suggested that cosmic ray acceleration takes place exclusively in so-called shock environments where collision events produce neutrinos.

In the new work, Balagopal V and colleagues performed two different, independent, types of analysis on more than 10 years’ worth of neutrino observations in the 1 TeV to 10 PeV range. The first analysis involved measuring a sample of neutrino cascades and a sample of neutrino tracks in the detector. The team then combined the results of both sets of measurements to characterize the neutrino spectrum.

The second analysis used a new event sample consisting of neutrinos with “interaction vertices” inside the detector. “This sample therefore contains neutrinos of all flavours,” explains Balagopal V, “and we performed a fit to the energy spectrum using these events.”

Both analyses arrived at the same conclusion, rejecting a single power law distribution with a confidence of more than 4𝜎 (the usual maximum confidence being 5𝜎). The best fit for the data was instead a broken power law, with the spectrum of neutrino energies falling more steeply at higher energies than at energies below around 30 TeV, Balagopal V tells Physics World.

“This implies that there are fewer lower energy neutrinos when compared to what one would obtain with a simple extrapolation of the prediction from higher energies,” she says. “This changing shape of the spectrum can indicate several things: either a changing population of cosmic neutrino sources; or a change in their production mechanism.” If cosmic neutrinos come from more than one kind of astrophysical source, she adds, then each type may be accelerating cosmic rays in a different way.

A final option, Balagopal V notes, is that some theories suggest that interactions with dark matter can also produce such a spectral feature. “With these measurements, we have opened up the possibility of discoveries in any of these directions,” she says. “With more detailed analyses, we could identify if there are additional features in the energy spectrum and we are already analysing new IceCube data to this end.”

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In the ongoing quest to improve cancer treatments, the radiation oncology community is looking to add to its armoury of radiation-based treatments. In particular, radiopharmaceutical therapy (RPT) – also known as molecular radiotherapy (MRT) – and the emerging sub-field of theranostics are set to play an expanded role as radiation medicine shifts towards a more integrated, multidisciplinary approach.

RPT is an evolving modality that uses a tumour-targeting molecule attached to a therapeutic radioisotope to deliver radiation directly to tumour cells. Theranostics takes this approach a step further, pairing the therapeutic radioisotope with a diagnostic analogue to image the disease before therapy and predict how the radioactive drug will be taken up by a specific patient.

“Interest in theranostics has really exploded since the clinical approvals of two radioactive drugs that are being used right now to treat patients,” explained Jeff Kapatoes, vice-president of regulatory, physics and product at Mirion Medical, at the recent QA & Dosimetry Symposium (QADS) hosted by Sun Nuclear.

The two approved drugs – Lutathera and Pluvicto – are approved for treating neuroendocrine tumours and certain prostate cancers, respectively, currently for later-stage disease but with multiple clinical trials ongoing to expand their remit to early-stage disease. “There are also active trials that treat other disease sites, such as lymphoma, breast and lung,” Kapatoes noted. Alongside, some 70 companies are developing their own therapeutic radiopharmaceuticals, with nine candidates now in phase-three trials and closing in on approval.

But despite its vast potential, theranostics is still in the early stages of widespread clinical adoption. While external-beam radiotherapy benefits from established treatment and quality assurance methodologies, this is simply not the case for theranostics. And as demand continues to grow, it’s vital that the full theranostic workflow is standardized – from radioisotope production through to final delivery to the patient.

Mirion Medical can support this integration of theranostics into radiation oncology, offering a broad portfolio of products designed for the entire theranostics lifecycle. The transition will also rely heavily on the contribution of medical physicists, who are uniquely positioned to implement theranostics programmes within their institutions.

Theranostics today

Speaking at the QADS event, John Sunderland from the University of Iowa explained the current situation. “The reality is, in external-beam radiotherapy, there are methods to ensure that the beam reaches the right place and the energy deposited is what you think. In RPT, you don’t control where the dose goes, biology and biochemistry do.”

He described a typical theranostic prostate cancer treatment, which begins with a PET/CT scan to visualize how a diagnostic radioisotope binds to the patient’s prostate cancer cells. Candidate patients are then injected with a therapeutic radioisotope comprising the same cancer-targeting molecule labelled with the beta emitter lutetium-177 (¹⁷⁷Lu), which delivers highly localized radiation dose to the tumours. Importantly, this drug can also be imaged, using SPECT/CT to track its delivery.

Serial imaging enables treatment to be tailored to a patient’s response. Sunderland discussed one patient who had almost complete response after three treatments with Pluvicto (which is delivered in up to six cycles of 200 mCi). “There’s no reason to keep giving radiation dose to this patient, which might result in adverse events, we may as well stop,” he explained.

More typically, a patient will exhibit stable disease or a modest response – likely because not enough dose was delivered to the tumour. Simply increasing the amount of injected activity, however, risks increasing the dose to non-target organs such as kidneys or bone marrow. “Instead, we’re trying to move to dosimetry-modulated RPT where you modulate the amount of injected activity based upon the dosimetry in that first cycle,” Sunderland explained. “Then you can optimize the efficacy while maintaining critical organ toxicity levels to below where they might have adverse effects.”

Such dosimetry modulation requires three things: accurate measurement of the injected activity using a radionuclide calibrator; quantitative SPECT mapping of the absorbed radiation dose; and uniform software tools. But challenges remain, due to a lack of standardization at all three stages.

“Even expert physicists making the same dosimetry measurements with the same image data could vary by 20 to 30%, just because of the methodology they choose,” said Sunderland. “We have to standardize. We’re not where the external-beam people are, we’re all doing it differently because it’s so new.”

The PDIB project

The Precision Dosimetry Imaging Biomarker (PDIB) project hopes to remedy this situation via three parallel projects: establishing a network of secondary standards calibration laboratories (SSCLs); standardization of SPECT/CT scanner calibration procedures; and standardization of dosimetry calculation workflows. “Only if we can do that are we actually going to be able to define our radiation dose-effect curves, as the external-beam field has been doing for years,” said Sunderland.

The first project aims to enable accurate measurement of the injected dose. To achieve this, four SSCLs – at BC Cancer, the University of Iowa, the University of Alabama Birmingham and the Belgian Nuclear Research Centre – will work with the national metrology labs NIST and NPL to support clinical trials worldwide. Using high-purity germanium detectors, the labs will perform absolute activity measurements of the six most commonly used radionuclides (¹⁷⁷Lu, ¹³¹I, ²²⁵Ac, ¹¹¹In, ²⁰³Pb and ²¹²Pb). These samples can then be used by radiopharmacies and imaging/therapy sites to adjust their own dose calibrators to the SSCL measurements, targeting an overall activity uncertainty of less than 3%.

The second project, designed to harmonize quantitative calibration of SPECT/CT for therapeutic radionuclides, involves 12 imaging sites across the US, Europe and Australia. “There’s no standard way to calibrate right now and there’s no way to validate the calibration,” said Sunderland. The plan is to calibrate seven common quantitative SPECT/CT scanner models, using three different phantoms and the six radionuclides, using SSCL-supplied samples to ensure accurate activities.

The final project addresses the dosimetry calculations. Led by five international experts (two in North America, two in Europe and one in Australia), the project will examine ¹⁷⁷Lu dosimetry for kidneys, bone marrow and tumours using 20 curated ¹⁷⁷Lu-DOTATOC datasets. The teams will use five cases to develop standard operating procedures, then test these procedures on the other 15 cases, using five different dosimetry software packages, to investigate inter-user dosimetry variability.

“Radiopharmaceutical therapy is a big deal,” Sunderland emphasized. “The market for nuclear medicine is growing exponentially; it’s going to be double that of external-beam radiotherapy by 2030. And there are not nearly enough nuclear medicine physicists to do this work.”

In the US, RPT is a shared domain between radiation oncology and nuclear medicine, with active discussion around which department should be handling radiation for therapeutic versus purely diagnostic purposes. In Europe, meanwhile, theranostics generally sits solely within the remit of nuclear medicine.

“We need to recruit the external-beam physicists into the fold,” said Sunderland. “From a dosimetry and physics standpoint, there’s a lot of overlap here and a lot of expertise.”

Supporting the theranostics workflow

This blurring of traditional boundaries between nuclear medicine and radiation oncology creates both opportunities and complexities. With a comprehensive portfolio of products that span both domains, Mirion Medical aims to ease this convergence of disciplines and support the physicists navigating this transition.

Designed to standardize and streamline the full theranostics workflow, ec² Software enables radioisotope manufacturers, radiopharmacies and clinical facilities to provide traceability and support precision, safety and regulatory adherence.

“Products from ec² Software enhance precision through accurate dose tracking and documentation across the radiopharmaceutical lifecycle, improve safety by reducing manual steps, and support regulatory compliance with auditable records,” Kapatoes explained. “Overall, ec² Software helps health systems move from fragmented processes to consistent, scalable operations.”

Meanwhile, Mirion’s broader Radiopharma offering supports the physical and operational infrastructure required for safe and accurate delivery of theranostic procedures. This includes dose calibrators, SPECT calibration phantoms and shielding systems from Capintec, all of which will be key enablers for the introduction of dosimetry-modulated RPT.

“While ec² provides the workflow, traceability and compliance layer, Mirion’s hardware and monitoring solutions address the measurement, protection and safety environment in which those workflows operate,” said Kapatoes. “Together, they create an integrated approach, linking what’s happening operationally with what’s happening physically. This alignment helps health systems standardize processes, reduce variability and maintain compliance as programmes scale.”

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Smaller, faster, more efficient: the quest for relentless miniaturization has served the global semiconductor industry well – and, in fact, continues to do so, with the number of transistors on a microchip still doubling (per Moore’s Law) roughly every two years. Increasingly, however, applied scientists and engineers are redefining semiconductor progress along multiple axes of innovation.

The drivers? On the one hand, there is a convergence of new materials, advanced device concepts and heterogeneous integration (which combines different materials or technologies within one high-performance microelectronics package); on the other, the market-pull of disruptive technologies like AI and machine-learning, quantum computing and electrified transportation.

For the UK, “the opportunity is real and the direction is clear”, according to a new semiconductor metrology roadmap published by the National Physical Laboratory (NPL), the UK’s National Metrology Institute.

Following a three-year consultation exercise with around 500 semiconductor experts, the report – UK Priorities in Semiconductor Metrology and Standards to Drive Innovation and Growth – states that the UK must invest in foundational metrology and standardization capabilities to unlock commercial opportunities across the semiconductor supply chain.

“There’s been a gap in understanding – in policy circles and in industry – about the critical role that semiconductor metrology plays in defining what good looks like,” says Gareth Edwards, head of advanced manufacturing and materials strategy at NPL. “Publication of this roadmap is an attempt to reset the narrative by ensuring that metrology and standardization are treated as integral components of the UK’s semiconductor strategy, not as peripheral technical concerns.”

By shaping how emerging semiconductor technologies are measured, qualified and trusted, the roadmap argues the UK can help define the rules of future markets, support resilient supply chains and convert scientific excellence into sustained economic and strategic advantage.

“There’s a lot at stake here,” adds Edwards. “The countries that drive the conversation on standards development can ensure first-mover advantage for their domestic manufacturing base when it comes to roll-out and acceptance of new semiconductor materials, processes and products.”

Punching above its weight

While the NPL roadmap acknowledges that the UK is unlikely to become a leader in large-scale advanced silicon manufacturing alongside the likes of Taiwan, Korea and the US, the country has notable strengths that align well with the long-term trajectory of the global semiconductor industry.

The UK’s academic and industrial R&D base, for example, consistently punches above its weight, underpinning world-class capabilities in compound semiconductors, materials science, photonics, power electronics, device modelling, semiconductor tooling and applied measurement science. Through organizations like NPL and BSI, the national standards body, the UK also has an unrivalled reputation for rigour and trust in metrology and standardization.

All of which matters even more given that next-generation semiconductor technologies are advancing much faster than the standards that govern how they are made, tested and integrated.

For context, mature silicon platforms are built upon decades of recognized best-practice and widely adopted specifications. Novel materials and device architectures, by contrast, often arrive without agreed performance metrics, standard test methods or even consistent terminology.

“This means that NPL, and other national metrology institutes like it, have significant work to do where new technologies have to compete or integrate with incumbent semiconductor products,” explains Sebastian Wood, principal scientist for semiconductor materials and devices in NPL’s electronic and magnetic materials group.

The NPL roadmap therefore lands at an apposite moment, setting out 12 metrology priorities to address the UK’s capability gaps in semiconductor technology and manufacturing (see “Made to measure: the path to next-generation semiconductors”, below).

The roadmap’s call-to-action spans the full life-cycle of semiconductor innovation – from materials and structures, through process development and scale-up, to device and system performance – with the aim of exerting influence where global semiconductor markets are still evolving rather than competing where they are already mature.

“As a facilitator,” says Wood, “NPL’s role is to address these metrology priorities by mobilizing key stakeholders across the UK semiconductor ecosystem.”

Operationally, that means bringing together representatives from industry, academia and government to work on all aspects of semiconductor performance metrics, benchmarking and standards development; at the same time, reinforcing the UK’s voice in the European and international standards development organizations. “We want the UK to be a country that defines semiconductor standards, not one that must adapt to them,” he adds.

Joining the semiconductor dots

Encouragingly, the effort to translate the strategic vision for “UK Semiconductor” into economic upside is already under way. The official launch of the semiconductor metrology roadmap is a case in point, with a well-attended workshop at NPL’s Teddington campus in March yielding recommendations for delegates at all levels of the semiconductor supply chain.

The roadmap states that industry must engage earlier and more consistently in pre-competitive metrology and standards activity, recognizing it as an investment in market access and competitiveness. Academia, meanwhile, must align fundamental research more closely with the measurement and qualification needs that shape industrial adoption. Government, too, has a critical role to play by recognizing standards as strategic assets and through targeted funding for pre-competitive standards metrology and research.

“The metrology and standards roadmap offers a framework for a more joined-up innovation pipeline in semiconductor technology,” Wood concludes. “In this way, we will enable UK companies to not only translate their breakthroughs in basic science, but commercialize, scale and project them on global markets.”

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A memory device that can operate at temperatures over 700 °C could enable electronic systems to withstand harsh conditions with less need for cooling. The device, which is a memristor based on graphene, tungsten and a hafnium oxide ceramic, can store data for over 50 hours, has a working voltage of just 1.5 V, and is robust to more than 10⁹ switching cycles. It also has a high switching speed of just tens of nanoseconds, according to its developers at the University of Southern California (USC), US.

“Our work provides one of the most critical electronic components – memory – for a wide range of applications, particularly in extreme environments,” says Joshua Yang, who directs USC’s Center On Neuromorphic Computing undeR ExTreme Environments (CONCRETE). “These include space exploration, deep-Earth drilling (for geothermal energy) and nuclear and fusion energy plants in which intense heat is generated.”

Heat-tolerant electronics could also dramatically reduce the need for energy-intensive cooling systems, cutting both power consumption and fan noise, Yang adds. “Our work also shows that these devices require significantly lower voltage and current to operate at elevated temperatures – meaning higher ambient temperature can actually improve energy efficiency of computing systems.”

A device to remember

Rather than being fixed, the resistance of a memristor (or memory-resistor to give it its full name) changes depending on the current or voltage previously applied to it. This means that specific resistances can be programmed into the devices and subsequently stored. Importantly, the “remembered” value of the resistive state persists even when the power is switched off, making it a non-volatile form of electronic memory.

Memristors are also capable of processing large amounts of data in parallel, making them faster and more energy-efficient than conventional memories for certain calculations such as matrix-vector multiplication. They are therefore useful for in-memory computer technologies, including those that are now routinely employed in artificial intelligence (AI) hardware.

An unexpected discovery

The memristor described in the new CONCRETE Center study consists of a hafnium oxide (HfO₂) layer sandwiched between two electrodes: a tungsten one on top and a graphene one on the bottom. Tungsten has the highest melting point of any metallic element, and the study’s first author, Jian Zhao, notes that graphene (a sheet of carbon just one atom thick) can also withstand high temperatures without degrading. Nevertheless, Yang says they didn’t specifically set out to make a super-high temperature device.

“As often in science, this work originated from an unexpected discovery,” he explains. “We identified a material stack with significantly higher temperature tolerance while investigating something else completely – namely trying to build a different kind of device using graphene.”

Understanding why this stack could withstand such high temperatures and validating their hypotheses took considerable effort, Yang tells Physics World. The team used a combination of advanced electron microscopy, spectroscopy and first-principles calculations to work out the physical mechanisms behind the process, he adds.

The role of graphene

In conventional ceramic-based memristors, like those with a platinum bottom electrode, high temperatures cause the metal atoms from the top electrode to migrate through the ceramic layer until they reach the bottom electrode. When this happens, the two electrodes permanently connect and the devices short-circuit.

In the USC team’s memristor, though, this simply wasn’t happening. “Graphene puts an end to this process,” Yang explains. “Tungsten atoms still drift towards the graphene electrode as expected, but because of its surface chemistry and structure they cannot anchor onto it. These atoms therefore end up migrating away from the electrode, so avoiding short-circuiting and device failure.”

The researchers, who report their work in Science, say that one future research direction might be to search for materials that have a similar surface chemistry to graphene, but are easier to handle. Their next goal, which they acknowledge will be challenging, is to integrate their high-temperature memristors with logic devices (such as those based on SiC substrates) that can also withstand extreme temperatures.

To advance their memristor technology, Yang and his colleagues Glenn Ge, Miao Hu and Qiangfei Xia have founded a start-up company, Tetramem Inc., focused on developing memristor-based machine learning/AI accelerators. Though scaling up their devices will take time – the current examples were made by hand in the lab at the sub-microscale – Yang says that creating high-operating-temperature accelerators could enable intelligent computing in extreme environments, including space applications or datacentres.

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Complex oxide materials form a large family of compounds with highly tuneable electronic properties, making them important for electronics, magnetic devices, and energy technologies. In many of these materials, electrons interact strongly with lattice vibrations and form polarons, quasiparticles consisting of an electron plus the surrounding lattice distortion. Polarons play a key role in determining how materials conduct electricity, but they are difficult to study because theoretical modelling requires advanced methods to describe strong electron-lattice interactions characteristic of polarons, and experiments must be performed on ultraclean samples to reveal intrinsic behaviour.

In this work, the researchers combine experimental and theoretical approaches to study polarons in TiO₂, a material that is ideal for this purpose because it has a simple crystal structure, well‑known phonon modes, well‑characterised defects, and strong, reproducible electron-phonon coupling. They use a state of the art simulation method called first‑principles electron‑phonon diagrammatic Monte Carlo (FEP‑DMC), which accurately predicts polaron formation and transport. The calculations predict a room temperature mobility of around 45 cm² V⁻¹ s⁻¹ and a characteristic temperature scaling of μ ∝ T⁻¹·⁹, while also revealing microscopic details of polaron structure, phonon cloud distribution, and lattice distortion that experiments alone cannot access.

The team then grew ultrahigh‑quality TiO₂ thin films with controlled oxygen vacancies using hybrid molecular beam epitaxy, achieving record high electron mobility in excellent agreement with the theoretical predictions. Microscopy and spectroscopy measurements show that oxygen vacancies act as intrinsic n‑type dopants and strongly influence low‑temperature transport, including in‑plane resistance anisotropy and signatures of the Kondo effect.

Together, these results provide the most detailed picture to date of how large polarons move in TiO₂ and demonstrate that the theoretical method is a reliable predictive tool for polaronic materials. This unified framework will help guide the design and engineering of improved electronic and energy materials in the future.

Do you want to learn more about this topic?

Review Phonons and thermal transport in graphene and graphene-based materials by Denis L Nika and Alexander A Balandin (2017)

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Weyl semimetals are quantum materials in which electrons behave as if they are massless, moving with a linear energy-momentum relationship similar to photons. These materials also host Weyl fermions with a built‑in chirality, meaning their spin and momentum are locked in either a left‑ or right‑handed configuration.

A distinctive feature of Weyl semimetals is the presence of Fermi arcs which are surface electronic states that connect projections of bulk Weyl nodes. Because these arcs inherit the chirality of the underlying Weyl fermions, their motion is directionally biased and highly sensitive to the surface environment. This makes them promising for surface‑state engineering in topological devices.

The researchers show that the surface of the Weyl semimetal Co₃Sn₂S₂ can generate a strong, tunable second‑order nonreciprocal electrical response, which depends sensitively on the surface termination and can be further controlled by adjusting the surface potential. Crucially, when the Fermi arcs undergo a Fermi arc Lifshitz transition, a change in how the arcs connect across the surface Brillouin zone, the nonlinear current reverses sign. This sign flip arises from the chiral nature of electron velocities on the arcs.

The work demonstrates that measuring nonreciprocal transport provides a direct and experimentally accessible fingerprint of Fermi arc topology, offering a practical route to track and control surface states in Weyl semimetals without relying on complex surface‑sensitive probes.

Do you want to learn more about this topic?

Recent progress on correlated electron systems with strong spin–orbit coupling by Robert Schaffer, Eric Kin-Ho Lee, Bohm-Jung Yang and Yong Baek Kim (2016)

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A non-invasive cancer therapy known as tumour treating fields (TTFields) uses low-intensity alternating electric fields to inhibit cancer cell division and cause cell death. A new study providing fresh insights into how the applied electric fields kill cancer cells could help optimize future treatment of the brain cancer glioblastoma (GBM).

Most patients with GBM will have surgery to remove as much of their tumour as possible, before undergoing radiotherapy and chemotherapy. For newly diagnosed or recurrent GBM, tumour growth or spread can sometimes be slowed by adding in TTFields treatment. TTFields directs low-intensity (1–3 V/cm) alternating electric fields through the scalp to the tumour via insulated ceramic transducer arrays. The 200–300 kHz frequencies precisely target the rapidly dividing GBM cells, creating biophysical forces that disrupt cell division.

Simultaneously, the interaction of the electric fields with local conductive biological tissue heats those areas to between 38 and 39.5°C. While careful thermal management is required to prevent this “intrinsic mild hyperthermia (iMH)” side effect from injuring the scalp, studies in pancreatic cancer models have shown that deliberate application of additional hyperthermia in combination with TTFields can enhance cytotoxicity and inhibit cell migration. In this latest study, a team of researchers, led by Aili Zhang from Shanghai Jiaotong University in China, investigated whether the intrinsic heating during TTFields treatments for GBM could be optimized to produce similar advantageous effects.

“Our initial interest was to understand the biological effect of the electric field itself to find out why TTFields therapy works for some people but not for others,” explains Zhang. “As we looked more closely, we found that applying the field inevitably generates heat, which makes it difficult to distinguish the pure electrical effect from the accompanying thermal effect.”

That problem led the team to focus on electrothermal decoupling, in other words, separating the electrical and thermal components: an important step for clarifying the exact mechanism by which the GBM cancer cells are killed and for developing possible treatment optimization protocols.

As detailed in Physics in Medicine & Biology, Zhang and colleagues used numerical simulations to help them create an in vitro experimental platform capable of decoupling TTFields’ electrical and thermal components. The 230 kHz, 2 V/cm electric fields were applied via custom-designed, conductive, 2 mm-wide titanium electrodes created to safely enable precise delivery to in vitro wells containing murine GBM cells.

The team used numerical modelling to estimate temperature, and to optimize the electrode geometry and spacing such that a stable and sufficiently uniform electric field could be generated in the central monitoring area where the cells were being analysed.

“Just as importantly, the modelling told us how much intrinsic heating would be generated during TTFields exposure and how to compensate for it. Based on those results, we could set the incubator conditions to create a pure electric condition, a pure thermal condition and the combined TTFields condition,” explains Zhang.

Their results revealed that while the electric field component of TTFields was more closely associated with suppressing the proliferation and migration of cells, the decrease in both cell viability – thanks to elevated levels of calcium ions which help mediate cell death – and metabolic activity was primarily due to the thermal iMH.

“We became genuinely excited when the decoupled experiments started to show that the electric and thermal components were not simply producing the same biological effect at different intensities, but were contributing in clearly different ways,” Zhang tells Physics World.

“That was a significant moment because it suggested that the heat generated during TTFields should not be viewed only as an unwanted by-product, but as a potentially meaningful therapeutic component,” she continues, explaining that, importantly, “the combined TTFields condition performed better than would be expected from a simple additive effect”. This electrothermal synergy, the researchers believe, comes from the thermal component sensitizing the cells by increasing membrane vulnerability and disturbing calcium homeostasis, thereby allowing the electric field to more effectively drive cell death.

Next, Zhang plans to confirm the synergistic effect at the molecular level and “systematically examine how the electrothermal interaction changes across different TTFields frequencies, field strengths and thermal conditions for different GBM human cell lines”. The ultimate aim is to find the “optimized treatment protocol” for glioblastoma. Understanding such heating effects could also help optimize other medical treatments such as cardiac ablation, she adds.

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A first-in-human study from researchers at the Mayo Clinic has shown how proton therapy could provide a new treatment option for patients with hard-to-treat ventricular tachycardia (VT), a life-threatening heart rhythm disorder. In the small group of patients examined in this early feasibility study, the treatment led to a 79% reduction in VT episodes.

VT is a type of abnormal heartbeat in which faulty electrical signals in the ventricles cause the heart to beat too quickly, meaning that it can’t pump enough blood around the body. Treatments include antiarrhythmic drugs or the use of catheter ablation to destroy the areas of myocardium (cardiac muscle) responsible for the abnormal signals. Sufferers can also be fitted with an implantable cardioverter-defibrillator (ICD) that automatically delivers a shock to reset the heart’s rhythm during a VT attack.

Some patients, however, don’t respond to conventional therapies, including antiarrhythmic medications and catheter ablations, and ICD shocks can significantly impact quality-of-life. For these cases, cardiac radioablation – which uses external-beam radiotherapy to target the problematic myocardium – is under investigation as an alternative, catheter-free treatment for VT.

Previous clinical studies of cardiac radioablation have employed photon-based irradiation, which can expose surrounding cardiac tissue to low-to-moderate radiation doses. Beams of protons, on the other hand, deposit almost all dose at a defined depth (the Bragg peak) and could enable more precise targeting with reduced irradiation of nearby healthy tissue.

“The main motivation for investigating cardiac radioablation is to improve upon the limitations and suboptimal outcomes of catheter ablation of VT in some patients,” explains lead investigator Konstantinos Siontis. “The motivation specific to protons is the potential dosimetric advantage, allowing more precise myocardial targeting while minimizing radiation to surrounding cardiac and extracardiac structures compared with photons.”

In this new study, reported in Heart Rhythm, Siontis and colleagues used proton-based cardiac radioablation to treat seven patients with advanced cardiomyopathy (disease of the heart muscle) and recurrent VT despite drug treatment and previous catheter ablations.

First-in-human investigation

To define the target myocardium for radioablation, the team integrated data from multiple imaging modalities (primarily MRI, plus CT) with information from electrocardiogram (ECG) and electrophysiology mapping originating from the patient’s prior invasive ablation procedures. The CT images were then used to contour the target and organs-at-risk (OARs) and for treatment planning.

The researchers designed treatment plans to deliver a single 30 Gy fraction of expiration-gated intensity-modulated proton therapy to the cardiac internal target volume (ITV, the target myocardium expanded to include cardiac motion) while sparing surrounding OARs. They point out that, due to safety uncertainties in thisfirst-in-human study, they took a generally conservative approach to target definition. In all patients, at least 90% of the ITV received 100% of the prescription dose, while a median of 96.2% of the ITV received at least 95%. Importantly, only 4.3% of non-target myocardium received a dose of 20 Gy or above.

After treatment, the investigators performed follow-up evaluations for up to two years (median 514 days). Most patients experienced recurrent VT during this time, although less frequently than before the radioablation. Across all patients, the rate of VT events declined from 7.24 per patient-month in the three months before treatment to 1.52 per patient-month afterwards – corresponding to a 79% reduction in VT event rate. None of the group experienced serious treatment-related side effects and key heart function measures remained largely stable.

All patients in this study had advanced structural heart disease with severely reduced ventricular function and recurrent VT, putting them at high risk of both arrhythmic and heart failure-related mortality. In line with this profile, two patients required heart transplantation (at 66 and 514 days after treatment) and three died (at 155, 502 and 529 days), due to progressive heart failure.

“This early feasibility study demonstrates that proton cardiac radioablation for refractory VT can be safely planned and delivered with encouraging reductions in arrhythmic burden and no clear treatment-related toxicity,” the researchers conclude. “These findings support the feasibility of proton-based cardiac radioablation and justify further investigation,” they write.

Siontis notes that alongside the emergence of cardiac radioablation techniques, catheter ablation tools are also constantly improving. “Radioablation is unlikely to replace catheter ablation broadly, but it could become an important complementary or salvage option for patients with refractory VT who are poor candidates for invasive procedures,” he tells Physics World.

The team is now planning a larger prospective trial to better define the safety, efficacy and optimal targeting. “We are also investigating improved radiation delivery techniques, such as optimizing treatment planning around cardiac motion,” says Siontis. “In parallel, we continue to investigate photon radioablation in a pivotal randomized trial (RADIATE-VT), while we also offer proton therapy as a compassionate use option for patients in need in our clinical practice.”

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Quantum mechanics is so full of strange phenomena that it’s not surprising that physicists have had to dream up some vivid metaphors to explain them. Who can’t help but think of cats in boxes when contemplating superposition or balls of jumbled yarn when musing over entanglement? Like all metaphors, these use familiar experiences to help understand the unfamiliar.

Metaphors come in many different types. “Love is a rose”, for instance, is a “filtrative” metaphor, in which a secondary subject (a rose) guides us how to perceive another, primary subject (love) by drawing our attention to key features.

In a “creative” metaphor, however, the secondary subject eventually becomes the technically correct term for the primary subject. This has happened over and over again in quantum mechanics: entanglement, superposition and spin are all examples.

A third kind is a “perceptual” metaphor, which seeks to recast our overall view of something. A good example is physician Lewis Thomas’s remark that the Earth is “most like a single cell.”

But one extraordinary metaphor proposed 10 years ago by Christopher Fuchs, a physicist at the University of Massachusetts Boston, involves a type of algae known as Euglena. Fuchs decided to invoke this single-celled, biological organism to help understand not just one quantum-mechanical phenomenon but possibly the deepest mystery of all: the relationship between quantum formalism and the world around us.

Subjective matters

Ever since Werner Heisenberg and others developed quantum mechanics more than a century ago, physicists have been debating what it means and what it says about the world. Over the years, there have been many different points of view, or “interpretations”, of quantum mechanics, but they all fall into two main camps.

One set claims that the formalism of quantum mechanics quantifies some actual, objective structure that existed even before humans and is independent of what we do. Another set of interpretations treats the formalism like a tool that lets humans make predictions about the world. In philosophical terms, the former interpretations are “ontological” and the latter “epistemological”.

Fuchs and a loose conglomerate of physicists and philosophers, however, have been advocating an entirely different approach, known as QBism. It says that any measurement we make – whether determining the spin of an electron or stamping our feet on the ground – is a new creation; it’s an experience that never existed in the world before. Quantum states aren’t therefore real states of affairs in nature but subjective probabilities we assign to our interactions with the world.

Subjective probabilities aren’t as strange as they sound, simply describing a user’s degree of belief about an individual event. Objective interpretations, in contrast, see probability distributions as physical. QBism’s conclusion that many pieces of the formalism are subjective simultaneously distances our subjective control over nature. For a one-horse race, I can predict the winner with certainty, but nevertheless, the race can still get washed out by rain. Even if I make a prediction with certainty about an event, nature can throw us a curveball and do otherwise.

For Fuchs and his supporters, quantum theory is therefore an appendix to Bayesian probability theory. Originally developed by the British philosopher and statistician Thomas Bayes in the 18th century, it evaluates a user’s judgment about how likely an outcome is (such as whether a horse will win a race) rather than being about pre-existing states of affairs (such as passively recording the speed of particles in a gas).

Fuchs calls his interpretation of quantum mechanics QBism as it derives from the term “Quantum Bayesianism”. Quantum mechanics, according to Fuchs, is a “user’s manual” that “anyone can pick up”, devised by experienced players to guide individual experimentalists to make wise bets on measurement outcomes.

Subjective interpretations of quantum mechanics treat the formalism as something for individuals to use and apply for all kinds of physical phenomena

The key point is that while quantum state assignments are subjective, the rules underlying them aren’t. They have been analysed, evaluated and corrected over time by communities of physicists. Subjective interpretations of quantum mechanics treat the formalism as something for individuals to use and apply for all kinds of physical phenomena.

Enter Euglena

If you’re struggling to get your head around all of this, that’s where Euglena comes in. It’s a single-celled freshwater algae, roughly 50 microns long, that has a long whip or “flagellum” that can sense nutrients and propel the organism towards the food. The tail, which is the product of many years of evolution, helps only the organism to which it is attached. However, by studying it, we can learn not just about an individual Euglena but also the wider environment in which it moves.

The metaphor of Euglena’s tail therefore does two things. First, it expresses the idea that quantum formalism is a manual – a means to get around in the world. Second, it says something about how we interact with the world.

Each organism uses its inherited tail, constantly tested and improved by a community of others, to “guess” how to get around in its environment. But each time the organism does, it encounters something in the environment it never did before.

Euglena’s tail can, in other words, help us to explain why quantum mechanics can be both a single-user theory and the product of extensive study. “By dissecting it,” Fuchs wrote in a 2016 arxiv preprint (1601.04360), “you can learn something about the world that all of us are immersed in.”

Like all metaphors, however, Euglena has its shortcomings.

Imagine standing above the Euglena and observing it through a microscope. It would be perfectly reasonable to say that “there is” an environment that the organism senses “thanks to” the whip. We might also conclude that what a Euglena encounters is objective, independent of its presence, and could be predicted by the organism, provided it had enough data and processing ability.

But all this assumes we are looking down from above to adopt a point of view completely detached from Euglena and its environment; we, as researchers, are outsiders. The Euglena organism itself is different. It has no such outside standpoint and each move is creative, encountering a fresh environment.

Physicists have no external standpoint from which to look down on the world

Now here’s the key point of the metaphor. Quantum physicists, too, cannot become “outsiders”. They have no external standpoint from which to look down on the world. They have the quantum formalism, but it’s a guide to what we find in our fresh encounters with the world.

The critical point

Fuchs’s Euglena metaphor has a much broader scope than the other scientific metaphors mentioned above. It is not so much about comparing a piece of the organism to quantum mechanics, but a way of comparing an organism’s adaptation to its world to the experimentalist’s user-manual; in turn, it becomes a story about what the world is.

The Euglena’s tiny whip is a way to grapple with the ontological lesson of quantum mechanics. You might, in fact, call it an “ontologizing” metaphor.

Robert P Crease  (click link below for full bio) is a professor in the Department of Philosophy, Stony Brook University, US, and Gino Elia is a philosopher of physics who is spending 2026–27 at the Ludwig Maximilian University of Munich, Germany, e-mail gino.elia@stonybrook.edu

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Researchers at the University of Pennsylvania and the University of California, Los Angeles, have created a tiny, soft knot-like fibre that can jump metres into the air.

The fibre is less than a millimetre thick, and a few millimetres long and contains a Kevlar core surrounded by a shell of liquid crystal elastomer (LCE).

The Kevlar provides strength and stiffness while the LCE adds some flexibility and responsiveness.

“People think of a knotted fibre as something passive,” says Shu Yang from the University of Pennsylvania. “But if you design the elasticity and materials carefully, the knot itself becomes an active system.”

When the fibre is knotted it behaves like a spring held in place by a latch, which can be undone via changing the temperature.

When the temperature is increased to 60–90 °C, the LCE shell contracts and untwists, which loosens the knot just enough to trigger an abrupt untying.

All that stored elastic energy then converts into kinetic energy, propelling the fibre almost 2 m into the air – a feat comparable to the jumping capabilities of a springtail bug (for a video see here).

Changing the knot’s topology and the materials used allows the researchers to tune how the fibre moves after take-off. For example, a simple overhand knot results in a flipping motion while a figure-eight knot leads to the fibre spinning.

Inspired by the flight of Maple seeds, the team attached a thin, leaf-like appendage to the fibres, finding that where the wing is positioned on the knot resulted in the fibre landing far away or curving backwards towards its starting position.

Given the fibres can be activated with temperature, the researchers think the robot could find applications in agriculture and reforestation.

“We often start by exploring interesting phenomena,” adds Yang. “Then we ask how far we can push them and whether they can solve real problems.”

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See how much you know about the subject by trying our interactive crossword. Most of the clues are based on the article, but there are a few additional brain teasers thrown in. If you’re feeling stuck, check out the “assist” menu for help.

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The majority of printing processes today are performed using different coloured pigments. However, there’s another type of colour called structural colour, which typically uses nanoscale structures that interact with light to produce a colour. By refracting and reflecting light at specific wavelengths, these nanostructures can produce incredibly bright colours that (unlike pigments) do not fade over time, unless the structure is physically altered. Structural colour is often found in nature – creating the brilliant colours of a peacock’s tail feathers, for example – but has been difficult to print using conventional printers.

Most instances of creating structural colour involve diffracting light through periodic polymers or transparent oxide nanostructures, but these approaches cause a strong iridescence – where the colour changes depending upon the viewing angle – which can limit the practicality for some applications. To print structural colour materials, other options are needed.

Researchers from Kobe University in Japan have now achieved this, by developing a Mie-resonant silicon nanoparticle ink that can be printed onto flat or three-dimensional surfaces using an inkjet printer. Mie resonant systems are highly refractive particle systems that enhance light–matter interactions at specific wavelengths and can boost optical effects.

“We undertook this research to bridge fundamental Mie-resonant nanophotonics with scalable printing technologies, enabling structural colour to move from laboratory demonstrations to practical, large-area applications,” explains Hiroshi Sugimoto, one of the study’s lead authors.

The research team at Kobe University has been developing spherical crystalline silicon nanoparticles with a high refractive index and low extinction coefficient that reflect specific wavelengths of light to produce certain colours. These particles, ranging in diameter from 100–200 nm, were used as the basis for the new ink, moving away from more traditional, unprintable structural colour materials.

The researchers wanted to develop structural colour inks that can be processed like conventional inks or paints. However, they initially found that when the solvent dried, the particles tended to aggregate. This aggregation changed how the particles interact with light and degraded the colouration of the ink. To overcome this issue, the team coated the silicon nanoparticles with thick silica shells and formulated them into a water-based acrylic emulsion. Unlike the crystalline silicon particles, the protective shells have a low refractive index so they don’t they don’t bend the light. As such, they provide a transparent coating that prevents aggregation without affecting the structural colour output.

The researchers used the nanoparticle ink to print images on a flat polymer film and a 3D metallic surface, using an inkjet printer at resolutions of between 250 and 125 dots per inch. They found that the images exhibited optical asymmetry – showing a different colour when light passes through the image (transmission) to when it is reflected from above – due to the Mie refraction that the particles exhibit.

The researchers also found that that the hue can be tuned by changing the diameter of the nanoparticles. This allowed them to create multi-colour patterns with tuneable reflection/transmission colour asymmetry by using nanoparticle inks with different particle sizes.

“The most important finding is that we achieved structural colour printing using silicon nanoparticles, overcoming the long-standing reliance on periodic arrays in conventional structural colour systems,” says Sugimoto.

Potential applications of these tuneable and printable inks include anti-counterfeiting images, semi-transparent smart windows, smart displays and vibrant art pieces (that won’t fade over time). For example, when the ink is printed on to a monitor, the printed images will be invisible when the display is on. However, when the display is turned off, the images become visible, which allows for information display without using any energy.

When asked about where they plan to take the research next, Sugimoto tells Physics World that “building on this work, we aim to further control and exploit this optical asymmetry for multifunctional systems, such as anti-counterfeiting and decorative films on buildings and windows, using scalable nanophotonic printing”.

The research was published in Advanced Materials.

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Food physicists have a lot on their plate just now. Across academia and industry, the community faces systemic challenges, not least the obesity epidemic, mounting health-and-safety concerns around ultra-processed foods, and the regulatory backlash against plastic food-packaging waste.

The war in the Middle East is another uncomfortable wake-up call. While the effective closure of the Strait of Hormuz to commercial shipping has sent oil and gas prices soaring, that strategic choke point has also shut off around one-third of the seaborne trade in fertilizers, fuelling price spikes and warnings of global food shortages to come.

All these factors will intensify the push from policymakers and the public for a more sustainable “food system”. The goal is to make better use of water, energy and raw materials, while minimizing environmental impacts like deforestation and pollution.

What’s cooking?

The food-physics community is a diverse mix of senior academics, early-career researchers and R&D scientists from the food-and-drink industry. Many of them came together recently in Leeds, UK, at Food Physics X – the 10th annual conference of the food-physics group of the Institute of Physics (IOP). Top of the agenda was how the food industry can deliver nutritious and tasty products, while at the same time accelerating technology and process innovation to cut manufacturing costs and time-to-market.

“Food physics and its multidisciplinary practitioners have a key enabling role here,” says Zachary Glover, an industrial biophysicist who has chaired the IOP’s food physics group since 2021. “Collectively, the challenge lies not just in improving food security and resilience of supply, but also in supporting industry R&D initiatives towards enhanced productivity, circularity [to minimize waste] and environmental sustainability.”

Glover is optimistic about the food industry’s ability to reinvent itself, especially when it comes to addressing the growing regulatory and geopolitical challenges through new digital technologies. “AI and machine learning are already transforming best practice in research, publishing and education,” he says. “Our task as a food physics community is to leverage what these tools have to offer to boost innovation and minimize the risks of bland homogeneity in our at-scale food production.”

Yet reinvention for food manufacturers will not be easy. The path to smart manufacturing (what’s sometimes dubbed “industry 4.0”) is more of a digital evolution than a revolution – whether that’s using “cobots” to reduce physical loading during manual-handling operations or exploiting AI to control manufacturing processes.

“Nationally, there is a huge sunk cost in the food industry’s existing manufacturing asset base,” says Glover. “This cannot and will not be replaced wholesale, while economic and geopolitical factors will ultimately dictate the pace at which industry is able to disrupt itself with new digital technologies.”

Out of the lab, into the factory

Despite the conservatism of those in the food industry, academics are pressing ahead, with physics-informed AI and machine learning (PIAI and PIML) fuelling both technology push and food-process innovation. According to University of Leeds food physicist Megan Povey in her keynote presentation at Food Physics X, physicists have integrated fundamental models of transport phenomena with PIML to create hybrid model systems that are both data-efficient and physically consistent. “The payoff is a reduced reliance on costly trial-and-error experimentation,” she says.

Povey uses ultrasound spectroscopy for food characterization and ultrasound processing in food manufacturing R&D. She also focuses on the computer and mathematical modelling of foods, pointing out that PIML can now solve complex partial differential equations relevant to heat transfer, mass transfer, microbial inactivation and structural changes, even when limited data are available.

“PIML has improved the accuracy of forward and inverse modelling, accelerated virtual prototyping of food products, and increasingly supported the development of real-time digital twins [interactive computer simulations] for process optimization,” Povey told delegates at Food Physics X. She and her colleagues are putting such advances to practical use at the Leeds Food AI Lab, which brings together experts from a range of disciplines in sensing, machine learning, optimization and life-cycle assessment.

By training PIML models on food-system-relevant data generated using the lab’s “sensor-fusion” capability, the Food AI Lab and its research partners are, for example, transforming variable, low-value agri-food residues into reliable sources of sustainable protein – what’s known as “agri-food waste upcycling”. The lab also uses near-infrared spectroscopy and machine learning to detect allergens in powdered food and applies ultrasonic sensing, machine learning and Bayesian optimization to cut the cost and environmental impact of industrial cleaning processes.

“We are engaged in creating a more sustainable food industry at AI Food Lab,” Povey says. “Along the way, new measurement techniques, advances in mathematics, plus PIAI and PIML innovations will transform our understanding of the physics of food and nutrition.”   

For both Povey and Glover, who this summer ends his five-year stint as IOP food physics chair, being part of an organization that promotes and defends physics is integral to their professional identities. “With the help of our colleagues at the IOP, we weathered the COVID years with online events and have had three strong in-person annual conferences since then,” says Glover. “The feedback on our conferences is fantastic and it genuinely feels like our members want to be there, engaging face-to-face with their peers.”

For Glover, the food physics group is all about bringing like-minded scientists and engineers together, with a self-sustaining community of shared practice among the main achievements during his tenure as group chair. “Looking ahead, the group will continue to educate physicists in academia about the richness of questions in food science,” he says. “Just as important, we will engage industry scientists about the role of physics as a ‘quiet enabler’ of technology translation and food-product innovation.”

Food physics: the next generation

One notable feature of the IOP food physics group’s annual gathering is the prominence given to early-career researchers. Food Physics X in February was no different, with the work of two early-career scientists recognized by best poster awards.

Best oral poster: Molly Massey, University of Leeds, UK

The crystallization and melting behaviour of blends of cocoa-butter equivalents and milk fats using small- and wide-angle X-ray scattering (SAXS/WAXS).

The texture, gloss and shelf-life of chocolate are largely governed by fat crystallization during production, with developers’ ability to control the various crystalline forms (or “polymorphs”) of cocoa butter underpinning the quality of the end-product. However, growing demand for plant-based alternatives means that food manufacturers want to replicate the qualities of cocoa butter using cocoa-butter equivalents (CBEs).

With this in mind, Massey is using synchrotron SAXS/WAXS experiments to evaluate the role of anhydrous milk fat – traditionally used in milk chocolate to influence texture, polymorphic transitions and melting profiles – on the crystallization behaviour of CBE blends. Her long-term goal is to replicate those structural and thermal effects in dairy-free material systems that rely on milk-fat replacement blends.

Best paper poster: Ashley Roye, King’s College London, UK

Biomimetic modelling of oral mucus microstructure for understanding lubrication and taste transport.

Roye is investigating the interaction between the mouth’s salivary/mucus layers and “tastant” molecules, which are food compounds that trigger the sensation of taste. Her research focuses on how mucins (large protein molecules with carbohydrate attachments) in saliva and the mucosal lining mediate tastant transport to the taste buds and, in turn, how that process influences lubrication, mouthfeel and textural sensation of different food components.

The post In food physics, connection and collaboration are ingredients for a thriving IOP community appeared first on Physics World.

A new study shows that one of quantum mechanics’ strangest properties may be the secret ingredient that makes powerful quantum computers possible. According to research by physicists at A*STAR and the National University of Singapore (NUS), this property, known as contextuality, plays a central role in error-correcting codes – the mathematical tools that protect quantum information from noise. The finding suggests that quantum weirdness is not just an exotic curiosity. Instead, it’s baked into the very structure of the codes that keep quantum computers alive.

The tiniest disturbance – a stray vibration, a fluctuation in temperature – can corrupt the information that quantum computers process. To deal with this, physicists use quantum error correction: a clever strategy that spreads information across many physical quantum bits (qubits) and continuously checks them for faults, without directly reading the data they encode. But there’s a catch. Even a perfectly error-corrected quantum computer isn’t automatically powerful. To run any quantum algorithm you could ever want – what physicists call being “universal” – you need to perform a complete set of operations on your qubits, known as gates. These are the quantum equivalent of the logical operations that underpin classical computing.

It would be nice if we could accomplish this with gates that act independently on each physical qubit, as this would prevent errors from spreading between qubits. Unfortunately, a fundamental theorem called the Eastin-Knill theorem states that no single error-correcting code can implement a universal set of gates using only this type of gates, which are known as transversal gates.

The standard workaround is to use two complementary codes and switch between them, with each one supplying the transversal gates the other cannot. This strategy is called code-switching, and physicists regard it as one of the most promising routes towards truly capable quantum hardware.

For years, though, a basic question lingered: what allows code-switching to work? What resource makes universal fault-tolerant quantum computation possible in the first place?

A quantum resource hiding in plain sight

A new PRX Quantum paper by Kishor Bharti and colleagues at NUS and A*STAR points to a surprising answer: quantum contextuality. This is one of those quantum properties that sounds philosophical but has very real consequences. In everyday life, measuring something – say, the temperature of a room – gives you the same answer regardless of what else you measure at the same time. In contrast, the outcome of a quantum measurement can depend on the context – that is, on which other measurements you perform alongside it.

To make this more concrete, imagine you have two qubits. Some pairs of measurements you can perform on these qubits are incompatible. In mathematical terms, they do not commute with each other, and you cannot perform them simultaneously without one disturbing the other. Position and momentum are good examples: Heisenberg’s uncertainty principle states that they cannot be measured simultaneously at arbitrarily high precision. On the other hand, measuring the spin of qubit 1 along the x-axis and the spin of qubit 2 along the z-axis at the same time is perfectly allowed: these variables commute, so these measurements are compatible.

But here’s the really strange part: the statistics of what you observe for qubit 1 can depend on which measurement you choose to perform on qubit 2, even when the measurements are compatible. This isn’t a matter of ignorance or experimental imprecision. It is a provable, fundamental feature of quantum theory with no counterpart in classical physics, one that was made rigorous by the mathematicians Simon B Kochen and Ernst Specker in 1967 as a generalization of the more famous notion of quantum nonlocality articulated by John Bell.

Contextuality was already known to play a role in specific quantum computing tasks. In particular, it is important for a technique called magic state distillation, which is used to boost the power of fault-tolerant hardware. But the latest work goes much further. It shows that contextuality is not just a useful tool you can optionally invoke. Instead, it is a built-in feature of any error-correcting code capable of supporting universal computation.

A clean threshold with big consequences

Bharti and colleagues studied a broad family of error-correcting codes known as subsystem stabilizer codes, which use a mix of commuting and non-commuting measurements. They found a remarkably clean result: one of these codes is contextual if and only if it has at least two so-called gauge qubits, which are extra degrees of freedom that arise from those non-commuting measurements. Below that, the code’s measurement statistics can always be explained classically. Above it, quantum weirdness is irreducible.

When this criterion is applied to code-switching protocols, the finding becomes even more striking. Every major protocol known to achieve universal quantum computation – including well-studied examples like switching between the Steane code and the Reed-Muller code – sits above this threshold. As team member Andrew Tanggara explains: “We show that a large family of code-switching protocols must necessarily use a contextual subsystem code.” The mathematics suggests this is no coincidence: universality and contextuality appear to be inseparable.

A new lens for quantum hardware design

The team’s result means that contextuality now joins entanglement as a fundamental resource that error-correcting codes possess to enable universal computation. This gives quantum engineers and theorists a powerful new diagnostic tool. If a proposed code architecture turns out to be non-contextual, no amount of clever engineering will make it universal through code-switching alone. Contextuality is not a nice-to-have – it is a prerequisite.

The new findings also deepen our understanding of why quantum computers can do things classical ones cannot. It is not simply because qubits can be in superposition, or because they can be entangled. It is because quantum systems are contextual – and that contextuality, it turns out, is precisely what gets encoded into the structure of the most powerful error-correcting codes we know how to build.

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Large language models (LLMs) could help human scientists identify interesting research topics that have not previously been explored, say scientists at Germany’s Karlsruhe Institute of Technology (KIT). By analysing abstracts in materials science publications and mapping connections between different concepts, the model was able to generate predictions for future areas of interest that the KIT team says are more precise than those produced by traditional, rule-based algorithms.

The number of research articles published each year is increasing so quickly that it is impossible for scientists to keep up with everything, observes team leader Pascal Friederich, who heads a KIT research group on artificial intelligence for materials sciences. While experienced scientists know how to find connections between research areas within their field, identifying links between these and other, unfamiliar topics is a different story.

Training the model

Friederich suspected that machine learning (ML) could help solve this problem by identifying hitherto unthought-of combinations of topics and expanding the list of areas to explore. To test this hypothesis, he and his colleagues used an open-source LLM called LLaMa-2-13B to zoom in on key words and phrases in abstracts of papers in materials science. They then used a database of manually labelled abstracts to train the model, fine-tuning it to focus on only the most relevant concepts. These initial training data can be iteratively extended by adding LLM annotations that have been checked and corrected by human researchers.

Using this model, the KIT team isolated approximately 510 000 chemical formulae and 3 600 000 concepts from the 221 000 abstracts in their database – an average of 2.3 chemical formulae and 16.3 concepts per abstract. After removing duplicates, these numbers dropped to around 52 000 unique formulae and 1 241 000 unique concepts.

The researchers then constructed a graph that included only the concepts that appeared at least three times in the journal articles, and that consisted of at least two words. The resulting knowledge network has approximately 137 000 nodes, one for each key word or phrase.

Connecting the nodes

The team used a second ML model to connect nodes when different terms are often mentioned together. “For example, if our LLM observes that terms like ‘perovskite’ and ‘solar cell’ appear more often together, it will draw a new link in the concept graph,” explains Thomas Marwitz, who began the study as part of his undergraduate thesis. “Then an ML model analyses trends in these links to predict which combinations of scientific concepts could become more significant in the next two or three years.”

Marwitz, who is now studying for a master’s in computer science, explains that the ML model does this by analysing how links between terms change over time. When certain concepts are becoming linked with increasing frequency, this may indicate that a new field of research is developing. On the other hand, a decrease in the number of links might imply than certain topics are attracting less attention.

The results of these analyses suggest that LLMs could indeed be used to direct researchers toward topic combinations that had previously received little attention, Marwitz says. In follow-up interviews conducted as part of the study, researchers in many fields confirmed that at least some of the AI-generated suggestions were genuinely innovative and promising. Some examples include: “conventional ceramic” + ”graphene oxide”, “tensile strain” + ”molecular architecture” and “multiphase structure” + ”selective laser melting”.

Not “an invention machine”

According to Friederich, the concepts extracted are more precise than was possible with rule-based approaches. The LLM’s capabilities also reduced the amount of manual annotation work required. For example, it was able to extract concepts that were not present verbatim in the text, while also removing “filler” words and making plural-to-singular conversions.

However, Friederich stresses that the technique is not an “invention machine” for automating scientific discoveries. “It is simply an analytic tool that can help to identify new ideas and opportunities for collaboration more effectively,” he says. “Our aim is to provide targeted support for scientific creativity.”

The study, which is detailed in Nature Machine Intelligence, is clearly only a first step on the way to true AI-supported science, he tells Physics World. “Much still needs to be done to improve the methodology behind our approach, extend its scope beyond just core materials science and extend the capabilities of the AI system from idea generation to autonomous hypothesis formulation, planning, execution, and analysis,” Friederich says.

He adds that the study was a departure from the group’s usual research, and it was not easy to get funding for it. “I hope that more such bold and exploratory research ideas will receive support in the future, given that LLM-based agentic systems are starting to perform standard research tasks with increasing reliability and complexity,” he says.

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Predictions that black holes cannot form within a certain “forbidden zone” of stellar masses have gained support thanks to a new analysis of gravitational waves detected by the LIGO–Virgo–KAGRA network of observatories. The analysis, which was conducted by researchers at Australia’s Monash University, adds weight to the theory that stars between 50 and 130 times more massive than our Sun end their lives in a type of supernova that was predicted in the 1960s but has never been directly observed.

Most massive stars collapse at the end of their lives to form black holes. Theories of stellar evolution, however, suggest that stars in a middling-to-higher range of masses will instead explode as so-called “pair-instability” supernovas. These events are so powerful that they completely destroy the star, leaving nothing – not even a black hole – in its wake.

If this explanation is correct, there should be a gap in the observed range of black hole masses. Finding evidence of such a gap is not easy, but in recent years, researchers have developed a way of searching for it using observations of gravitational waves – the tiny ripples in space-time produced when super-heavy objects like black holes collide.

A mass gap for secondary black holes

In the new work, researchers led by Hui Tong analysed data from LIGO–Virgo–KAGRA’s fourth Gravitational-Wave Transient Catalog (GWTC-4), which contains information on the distribution of masses within binary black hole systems. Based on these data, the team report that there is indeed a gap in the masses of the smaller of the two black holes in the binary. None of these so-called secondary black holes had masses between 44 and 116 times the solar mass, M_⊙.

The masses of the primary (that is, larger mass) black holes in the binaries showed no such gap. However, the Monash researchers argue that their findings nevertheless support the “forbidden zone” theory. They point out that the mass range they identified is very similar to the range over which primary black holes in a binary start to spin more rapidly. According to Tong, this shift could mean that these black holes formed via a different mechanism. For example, they may have formed from merging black holes rather than directly from collapsing stars.

If confirmed, Tong says this hypothesis could change our understanding of how massive stars evolve and how black holes are born. “We are essentially using something invisible, black holes, as a record of some of the brightest explosions in the universe,” he says. “Instead of observing the explosion directly, we infer its effect from what is left behind in the black hole population. In doing so, we can connect the properties of these remnants to what happened inside the star at the moment of explosion.”

The challenge of detecting an absence

Although pair-instability supernovae were predicted six decades ago, Tong says that traditional light-based (electromagnetic) telescopes struggle to detect them because they are rare, distant and leave little direct trace that can be uniquely identified. In this respect, he says that gravitational-wave astronomy could be game-changing: “The detection of gravitational waves allows us to ‘hear’ the violent collisions of the most compact objects in the universe and directly measure the properties of black holes across cosmic time.”

Even with this new tool, though, the work was not without difficulties. One of the biggest challenges, Tong recalls, was figuring out whether patterns observed in the black hole masses were real. “A large part of our work therefore involved testing different assumptions in our models and checking whether the results still held,” he says. “That process takes time, but it’s essential for building confidence that we’re truly uncovering how black holes form and evolve.”

“Next generation gravitational wave observatories will be transformative”

Tong hopes that future gravitational-wave observations will steadily increase the number of detected black hole mergers, allowing researchers to build a much clearer picture of black hole mass distribution. “In the near term, current detectors such as LIGO will continue to improve this picture by finding more events and reducing uncertainties, helping us confirm how robust the features really are,” he explains. “Then, next generation gravitational wave observatories planned for the 2030s will be transformative. With their much greater sensitivity, they will be able to detect black hole mergers from across a large fraction of the observable universe, potentially observing tens of thousands of merging black holes per year.”

Turning gravitational wave astronomy from a field with hundreds of detections into one with an almost continuous stream of black hole signals would bring enormous advantages, he adds. “It would allow us to see far more distant and fainter systems, including black holes formed when the universe was only a few billion years old (compared to its current age of about 13.8 billion years), during its early and more active stages of star formation and trace how stars evolve over the history of the cosmos.”

The present work is described in Nature.

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The latest episode of Physics World Stories dives into a remarkable archival release. A series of audio interviews with Robert Oppenheimer, recorded in the 1960s, is now accessible through the American Institute of Physics (AIP). Made available for non-commercial use in collaboration with the Oppenheimer family, these recordings offer a rare chance to hear the physicist’s voice and experience his unfiltered thoughts.

AIP digital archivist Allison Buser guides listeners through the significance of the collection, interspersed with clips. The first interview (1960) captures Oppenheimer reflecting on the lead-up to and aftermath of the Trinity test. A 1963 oral history with science historian Thomas S Kuhn shifts focus to Oppenheimer’s personal journey and his views on quantum and nuclear physics. The final interview (1966), sees him discussing Enrico Fermi’s legacy and the physics community of his era.

Hosted by Andrew Glester, this episode provides a rare glimpse into one of the most consequential scientists of the 20th century. You can find links to the full archive material in the AIP newsletter, along with further context in this article by Allison Buser. You can also hear an interview with Kai Bird, co-author of American Prometheus, the book that inspired the 2023 blockbuster film Oppenheimer.

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Since taking up the role of CERN director-general earlier this year, Mark Thomson has already had to contemplate the consequences of funding changes within the UK’s research councils.

Late last year, UK Research and Innovation, the umbrella organization for the UK’s research councils, did not commit any further contributions towards a major £150m upgrade to the LHCb detector – one of the four large experiments at the Large Hadron Collider that continues to do pioneering science.

As we report in the Physics World 2026 Particle & Nuclear Briefing, unless the decision is overturned or other avenues of funding are found, the experiment will now finish operations in 2033 and not take advantage of the High-Luminosity LHC (HL-LHC) that is currently being installed at CERN.

Another item in Thomson’s in-tray will be setting the course for the next flagship collider at CERN after the HL-LHC finishes operations in the 2040s.

In the ongoing process to update the European Strategy for Particle Physics, the Future Circular Collider (FCC) is the preferred option. Constructed near the LHC, this huge 91 km circumference electron–positron collider will come with a significant cost of $18bn. Thomson could find it a hard sell with some of the funding needing to come from outside CERN’s 24 member states.

As physicist and historian Michael Riordan points out in the briefing, the eye-watering cost of the FCC together with the worsening geopolitics of a fragmenting world order could make funding and building such colliders risky.

There are still many open questions over building the FCC, and indeed the future of particle physics, and some of those issues are set to be discussed at the 17th International Particle Accelerator Conference, which will be held in Deauville, France, from 17-22 May.

Elsewhere in the briefing, we talk to six physicists working across the nuclear energy industry, highlighting how a background in physics can open many doors in this expanding sector, and take a look at an obscure theory of elementary particles that proved to be key to China’s re-emergence as a scientific nation after the Cultural Revolution had stalled its development.

• The free-to-read Physics World 2026 Particle & Nuclear Briefing is available here.

The post The Physics World 2026 Particle and Nuclear Briefing is out now appeared first on Physics World.

It is straightforward to produce polycrystalline metal films on wafers but producing single‑crystal metal films is far more challenging. Because single crystals have no grain boundaries (the joints between differently oriented crystal regions in polycrystalline materials), they offer much better electrical performance: higher conductivity, lower resistive losses, improved high‑frequency behaviour (important for high‑speed communication and 5G), and reduced noise for quantum technologies. As a result, methods for reliably producing single‑crystal films are highly sought after. 

Single‑crystal silver and copper films are particularly valuable. Silver is an exceptional conductor of both electricity and light, while copper provides excellent thermal management and reduces resistive heating. However, growing silver on copper is notoriously difficult because the two materials have a large lattice mismatch (13%), which normally introduces strain, defects, dislocations, and rough, low‑quality films. This makes conventional epitaxy essentially impossible. 

In this work, the researchers overcame this barrier using Atomic Sputtering Epitaxy, which allows precise atomic deposition, combined with post‑annealing to reduce twin boundaries. They discovered that the mismatch strain is absorbed entirely within the first atomic layer of silver. This occurs because the atoms at the interface shift sideways in a periodic, controlled pattern that releases the strain. This represents a new form of heteroepitaxy in which two materials with different lattice periodicities can still grow together seamlessly. 

They demonstrated wafer‑scale, defect‑free single‑crystal silver films on copper despite the huge lattice mismatch, enabling ultra‑high quality metal films for advanced optical and electronic technologies. This approach opens the door to new heteroepitaxial systems and provides a route to producing silver films with exceptional optical and electronic performance. 

“What we find most notable is that a 13% lattice mismatch, which would normally prevent clean heteroepitaxy, is absorbed almost entirely within the first monoatomic Ag layer at the Ag/Cu interface, allowing the film above to grow as if on its own native lattice and yielding wafer-scale, grain-boundary-free films with atomically flat surfaces. We hope this concept of a strain-absorbing monolayer interface can be extended to other dissimilar metal pairs.” – Professor Young-Min Kim, Sungkyunkwan University

Do you want to learn more about this topic?

Si/Ge nanostructures by Karl Brunner (2001)

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Physicists study ultracold lithium‑6 because it is a fermionic isotope of lithium: its nucleus contains three protons and three neutrons, giving it a half‑integer total spin. This makes lithium‑6 behave like other fundamental fermions such as electrons, protons, and neutrons, in contrast to lithium‑7, which has an integer spin and is a boson. According to the Pauli exclusion principle, fermions cannot occupy the same quantum state, so lithium‑6 provides a clean, controllable system for exploring how fermionic particles behave. It is also relatively easy to cool to ultracold temperatures, and its interactions can be tuned very precisely using magnetic fields. At these temperatures, atomic motion slows dramatically, allowing quantum mechanical effects to become directly observable. 

In this work, the researchers studied three‑body recombination processes, where three atoms collide and two of them form a molecule while the third atom carries away the excess energy. The escaping atom has information about how the three atoms interacted. By tuning the interactions with a magnetic field using a Feshbach resonance, the researchers were able to access a p‑wave resonance (where atoms collide with orbital angular momentum) rather than the more common s‑wave (head‑on collisions). P‑wave interactions are especially important because they are linked to exotic quantum systems such as topological superfluidity and strongly correlated fermionic phases. 

The researchers developed a highly stable technique to measure how often atoms are lost due to three‑body recombination for different orbital orientations of the collision. This high‑precision method allowed them to distinguish the orbital components, measure how the recombination rate changes with temperature and magnetic field and extract microscopic parameters that characterize p‑wave interactions. This work establishes a precise benchmark for p‑wave scattering theory, introduces a powerful method for probing direction‑dependent interactions, and lays the groundwork for exploring complex quantum phenomena such as anisotropic pairing, few‑body universality, and topological superfluidity relevant to future quantum technologies.  

Do you want to learn more about this topic?

Single atom detection in ultracold quantum gases: a review of current progress by Herwig Ott (2016)

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Dark points within light waves can travel faster than the waves themselves. This finding, which is based on new measurements by researchers at Technion – Israel Institute of Technology, confirms a 50-year-old prediction and could help push atomic-scale imaging past its current limits.

Formally known as optical phase singularities, dark points are vortices within light waves where the wave’s amplitude drops to zero. “Simply put, these ‘zero points’ are points of complete darkness embedded within the light field,” explains study team member Tomer Bucher.

In the 1970s, theoretical studies by the physicists John Nye and Michael Berry suggested that such points could move faster than the waves in which they form. Until now, though, no-one had managed to test this prediction by measuring these structures’ movement experimentally.

Unprecedented spatial and temporal resolution

The Technion team’s experiments did not involve beams of light propagating through a vacuum. Instead, the researchers searched for optical phase singularities within flakes of hexagonal boron nitride (hBN), an atomically thin, two-dimensional (2D) material. Light waves in this material travel in the form of polaritons, which are particle-like entities that develop when the electric field of a photon interacts with the conduction electrons in a material. “These hybrid structures can be thought of as light waves that have unusually low velocities (roughly 100 times slower than the speed of light in vacuum) or as sound waves that have unusually high velocities,” Bucher explains.

Even with these reduced velocities, Bucher and colleagues needed special instrumentation to observe the processes at play deep within a single cycle of light. For this, they turned to a modified ultrafast transmission electron microscope (UTEM) composed of a laser and advanced opto-mechanical apparatus. Using an interferometry technique known as free-electron Ramsay imaging, they achieved what Bucher calls “an unprecedented combination of spatial and temporal resolution” of 20 nm in space and 3 fs in time.

To make sense of the complex interference patterns they observed, the researchers developed advanced computational algorithms to extract the exact amplitude and phase of the light-matter waves and reveal their hidden “singular skeleton”. They also deployed automated tracking algorithms to follow the exact space-time trajectories of dozens of singularities simultaneously across massive datasets.

These techniques revealed that when singularities with opposite charge meet, they annihilate each other. Just before this happens, though, they accelerate to extreme (formally divergent) velocities that exceed the speed of light in a vacuum – something that is allowed under Einstein’s principles of special relativity because the singularities are massless and carry neither energy nor information. “This result highlights a beautiful ‘paradox’ where the slower light-matter waves are the ones found more likely to host topological features that ‘race’ across its surface at impossible, superluminal speeds,” Bucher says.

A bad cavity comes good

As is often the case, the study started out as a completely different project. The researchers’ original goal was to study unique light-matter interactions and high-resolution dynamics in high-quality hBN cavities fabricated by a colleague, Bar-Ilan University’s Hanan Herzig Sheinfux, during a stint with Frank Koppens at ICFO in Barcelona, Spain.

“Ironically, the specific sample that became the focus of this paper was initially considered a ‘bad’ cavity,” Bucher recalls. “However, my colleague Arthur Niedermayr noticed something surprising in the raw data: patterns that looked like multiple singularities moving around. We therefore pivoted our focus; reconstructed the full phase and amplitude from the raw measurements; and created a fully aligned temporal movie to track these singularities frame by frame.”

It was during this tracking that the researchers observed vortices that accelerated to extreme velocities right before vanishing. This unexpected finding triggered a deep dive into the possible origins of such behaviour. Eventually, their search led them to Nye and Berry’s 1974 paper, as well as related work by Berry and Mark Richard Dennis in 2000. “Our experimental measurements agree incredibly well with the old and the new theoretical predictions,” Bucher says.

A universal advanced theory

As well as confirming the spatial statistics of the singularities laid out in these previous works, Bucher tells Physics World that he and his colleagues were able to extend the theory to capture the singularities’ full joint distance-velocity dynamics. Importantly, the extended theory is universal, meaning that the phase-space correlations they observed should apply to phase singularities across all types of wave systems, not just in optics. “Our findings will thus deepen our understanding of topological defects, which are common to all areas of physics – from superfluids to superconductors,” Bucher says.

In terms of direct applications, Bucher says the singularities he and his colleagues studied could be used to advance super-resolution microscopy and to encode high-density information within the orbital angular momentum of light. “The analytical methods we developed could help mitigate common artifacts in electron microscopy (such as the notorious ‘bee-swarm’ effect), ultimately pushing atomic-scale imaging to new limits,” he adds.

The researchers, who report their work in Nature, say they now plan to probe 3D line singularities and higher-order topological defects, which offer an even richer landscape for information encoding. “We also plan to investigate topological phases in other 2D materials and heterostructures, with the goal of resolving exotic phenomena like ‘optical skyrmions’ in real-time,” Bucher reveals. “Finally, we are actively developing near-field tomography techniques to capture the full 3D bulk dynamics of these complex waves – which if successful, will be a major milestone in electron microscopy.”

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Espresso, flat white, cappuccino, cortado – there are dozens of ways you can get your coffee fix. Every day more than two billion cups of coffee are brewed worldwide, making it one of the most traded products on Earth. In fact, it is the seventh most traded commodity on the planet (after crude oils, natural gas, gold, silver and copper).

Produced mainly in south and central America, south-east Asia and east Africa, coffee sustains the livelihoods of more than 25 million farming households. But its future is increasingly precarious. Coffee plants need the right temperature range, rainfall patterns and altitude to thrive, but climate change is disrupting it all.

This has led to falling yields and rising prices. For example, the price of Arabica beans – the most dominant coffee variety – rose by more than 80% in 2024. In the UK, this led to the price of beans at supermarkets rising 20% and the cost of some instant coffee surging by 40%, while coffee shop prices were up 30% from 2021 to 2024.

And it’s not just that coffee is affected by climate change – the climate is impacted by coffee. It has one of the largest carbon footprints of any plant-based product, mainly due to the clearing of tropical forests, fertilizer and water use, and processing techniques.

So how can those of us making the drinks help with the coffee and climate crisis?

At-home scientists

Coffee is an unusual drink. Unlike products such as whisky, wine and beer, it is brewed at the point of consumption, whether that’s in a café or restaurant, or in a home. “The very last step, which is probably the most complicated, is all done by untrained scientists,” says Christopher Hendon, a computational materials chemist and coffee expert at the University of Oregon.

It is estimated that it takes 155 people to make a cup of coffee – all the way from the farmer who plants the seed in the ground, to the barista who hands you your cup of coffee. “154 people can do their job perfectly,” says Dan Pabst, manager of innovations and product development at coffee provider Melitta North America. “But if that last person doesn’t pay attention, does something wrong and the coffee doesn’t taste right, they’ve just ruined all that hard work.”

This is where physics can help. Beyond longer-term, large-scale solutions such as re-engineering coffee plants or tackling climate change, physics can actually tell us a lot right now about what happens during the seconds and minutes it takes to brew a cup of coffee. It is a surprisingly complex process and by understanding it, we can improve the quality of the drink and even reduce the amount of coffee needed, cutting waste and helping the environment.

Under pressure

Let’s start with the espresso – those concentrated coffee “shots” you get in tiny cups that also form the base for your latte, americano or cappuccino (and many more).

The Specialty Coffee Association (SCA) has historically defined an espresso as a 25–35 ml beverage prepared from 7–9 g of coffee through which water heated to 90–96 °C is forced at 9–10 bars of pressure for 20–30 seconds. “While brewing, the flow of espresso will appear to have the viscosity of warm honey and the resulting beverage will exhibit a thick, dark golden crema,” states the SCA. This can be achieved using an espresso machine (figure 1), or with smaller contraptions at much lower pressures such as a moka pot or AeroPress.

1 Espresso basics

If you’ve ever had an espresso-based coffee, you’ll know that making that base shot of concentrated caffeine is more than just putting some beans in a machine and pressing go.  Like with any experiment in a lab, there is a strict process with a range of variables (and a bunch of lingo). Here’s a quick and very basic guide to making an espresso with an espresso machine:

1. The coffee beans are ground down into a powder-like substance
2. The ground coffee is then measured out in a “basket” at the end of a “portafilter” (top left)
3. To ensure this coffee is evenly distributed, baristas then lightly tap the basket, and some may manually move it around
4. Next the coffee is pressed down in the basket using a “tamper” to make it tightly and evenly compacted (top right), creating the coffee “puck”
5. Before the portafilter is attached, it’s a good idea to purge the machine with water to ensure no contamination from the previous brew
6. Now it’s time to actually “pull the shot”. The portafilter clicks into place (bottom left) and, if following the historical definition, high-pressure hot water (9–10 bars, 90–96 °C) is pushed through the puck for 20–30 seconds resulting in 25–35 ml of espresso (bottom right)

In 2017 the SCA and the Barista Guild of America surveyed baristas around the world to see how they were preparing their cups of espresso and if they were following the historical definition. Turns out that the average barista brews an espresso with 18–20 g of coffee in 25–30 seconds using water heated to 93 °C at 9 bars of pressure. This produces an average shot of 36.5 g.

Go online and you’ll also find all sorts of claims about how to produce a perfect coffee. “From a scientific point of view, this advice is often given with no substantial evidence,” says Maciej Lisicki, a physicist at the University of Warsaw. Keen to understand the real science behind a good espresso, Lisicki and his colleagues looked at the complexity of flow in coffee brewing (arXiv:2512.21528).

One frequent claim by coffee experts is that the optimal brewing pressure for an espresso is around 6–9 bars, and that pushing it higher yields diminishing returns. To find out why, Lisicki’s team rigged a café-grade espresso machine with a pressure sensor at the pump outlet, and a precision scale under the coffee cup so they could calculate flow rate. They prepared the puck using a high-spec coffee grinder and automatic tamper to ensure consistency, and then brewed shots of espresso at pressures ranging from 1 to 12 bars. “We strive for our espresso to be the same every time,” says Lisicki. To visualize their structure, the researchers also took X-ray micro-computed tomography (micro-CT) scans of the coffee pucks before and after brewing.

Fluid flowing through a porous medium, such as sand, glass beads or packed soil, usually follows Darcy’s law, with flow rate increasing linearly with the pressure of the liquid. But the researchers found that this was only true for coffee up to around 5 bars.  Above that, the flow rate flattened and then fell as pressure increased.

The team observed that as the coffee is brewed, the puck starts compacting under mechanical load, causing its pores to collapse and its permeability to decrease faster than the rising pressure can increase the flow. “The dynamics of espresso brewing is governed by this poroelastic effect,” Lisicki says. “There is an interplay between the porosity and the elasticity of the coffee matrix.”

Ultimately, the work confirmed what the coffee experts had observed. There is no point pushing the pressure beyond about 8 or 9 bars as the flow rate has already peaked.

The coffee in your coffee

Next, to explore how coffee dissolves over time, the team separated an espresso into different vials every five seconds as it brewed. An optical refractometer then measured the total dissolved solids in each vial. This, says Lisicki, tells you “how much coffee is in your actual coffee”.

The work showed that the first few drops of coffee that fall into your cup are very concentrated, but there aren’t many of them because flow rate is initially low. The flow rate then increases, but the amount of dissolved solids falls. This creates a sweet spot at around 15 to 20 seconds where the dissolved solids entering the cup peak, due to the balance between the increasing flow and decreasing solids.

Again, this tallies with expert opinion. “What we see is that most of the substance, the solubles, go into your cup within the first 30 to 35 seconds,” Lisicki says.

After talking to a friend who works as a barista, Lisicki and his colleagues also explored an annoying problem in coffee brewing known as channelling. This happens when the water finds a path of least resistance in the puck and forms a “channel” through the coffee grains. When they brewed coffees with artificially induced channels in the puck, the researchers found that the flow rate was as expected but the total amount of dissolved solids that were extracted was very low. Essentially, the water doesn’t permeate the rest of the puck, so you can’t extract all its coffee.

In fact, the team found that the more careless you are about preparing your coffee puck, the higher the chances of channelling. To mitigate this, you should stir the coffee grounds to make the puck as homogenous as possible and tamp it evenly. “You don’t need to tamp it very strongly, but tamping is important because if you don’t tamp then it’s easier for the water under high pressure to find a preferential flow path,” Lisicki says.

More from less

But even before you tamp your puck, how you prepare your coffee grains affects your drink’s quality. This is where grind size matters (figure 2). Back in 2020 Hendon and an international team were funded by the Coffee Science Foundation – the research arm of the SCA – to study ways to make highly reproducible espresso (Matter 2 631).

The group started by looking at what happens in the coffee grinder. You might think that a more finely ground coffee will maximize the surface area exposed to water, thereby maximizing extraction. Hendon and his colleagues discovered, however, that this was not the case.

2 Infiltrating the puck

When water is initially pushed through a dry espresso puck, it can take up to one-third of the brewing time to permeate the entire bed of ground coffee. But according to mathematician Ann Smith and colleagues, this process remains relatively neglected by mathematical models of coffee extraction.

“Understanding the infiltration process gives insights into the extraction rate across the coffee bed,” says Smith, who is based at the University of Huddersfield in the UK. “Over-extracting coffee results in bitter taste while under-extraction leads to both weak brews and wasted resources.”

To study infiltration dynamics through both a coarse and a fine grind, the researchers set up an espresso machine at the centre of a rotating X-ray tomography system, which allowed them to build 3D reconstructions of the pucks (Physics of Fluids 37 013383). They found that water travels more slowly but more uniformly through a fine grind (left) than a coarse grind (right), which can be seen in the above cross sections of the coffee pucks showing the absorption data for the first 8 seconds of brewing time. The researchers also built a flow model of the water permeation, which showed a good fit to the experimental data.

The team plans to build on the model by looking at other infiltration influences, such as brewing temperature and pores in the puck. “We have pioneered a new technique for experimentally validating coffee models, opening up several interesting avenues of future research,” the team says.

As grind size decreases, from coarse to fine, the amount of coffee that gets extracted initially rises but then peaks and falls. If the grind is too fine, the coffee bed clogs so that water can no longer percolate uniformly through it. Much like with channelling, some areas are over-extracted, while others are barely touched

“If you find the tipping point, you’ll realize the amount that you’re extracting on average [with a coarser grain] is actually much higher than if you ground finer,” Hendon explains. This means you also need less coffee to make an espresso of the same concentration.

The bottom line of the team’s experiments and mathematical modelling is that to get the most reproducible shots just use less coffee and grind it more coarsely.

Pabst echoes that advice: “My recommendation for people at home, without knowing anything they are doing, 90% chance that if you use less coffee and grind a little coarser [your coffee] will actually taste better.”

Hendon and his team trialled their “waste reduction protocol” at a small café in Eugene, Oregon in the US. By grinding more coarsely and reducing the dry coffee mass by 25%, from 20 g to 15 g, the business increased its revenue by more than $3000 over a year, without sacrificing drink strength or flavour.

Based on estimated US espresso consumption figures from the time, Hendon and his colleagues suggested that if their findings were implemented across the entire US, it could save the country about a billion dollars per year.

Volcanic coffee

It was not until Hendon teamed up with a volcanologist that he figured out why finer grinds clog the coffee bed and reduce extraction. Joshua Méndez Harper at Portland State University studies electrification in volcanic eruptions, where magma fragments charge up as they grind together in the plume, generating lightning. Coffee grinding, it turns out, creates a similar phenomenon (Matter 7 266, iScience 27 110639).

Together, Hendon and Harper found that friction between beans and the fracturing of beans during grinding generates static electricity. By passing coffee through a grinder a second time at a coarse setting, which removes fracturing from the process, the researchers discovered that most of the static charge arises from fracturing rather than friction.

According to Hendon, the more times you fragment your coffee, the more static electricity you generate. “You’re making lots of small particles when you grind finer, but they clump together to form an aggregate [because of static], which is effectively impermeable to water,” he adds (figure 3).

3 Caffeinated static

A team of scientists including coffee expert Christopher Hendon found that pores in a coffee puck clog if the coffee is ground too finely. After teaming up with volcanologist Joshua Méndez Harper, he discovered this was due to the grinding process introducing static charge, which caused the coffee to form aggregates, like those shown, that blocked water flow.

The solution, the researchers found, is to squirt a little bit of water on the beans before you grind them. “That totally suppresses the static accumulation,” Hendon says. Wetting whole beans with less than 0.05 ml of water per gram of coffee – or about 0.5 ml for an average espresso shot – resulted in a marked shift in particle size distribution by preventing clump formation.

But again, the coffee experts got here first. In the coffee industry, this is known as the Ross droplet technique and was anecdotally thought to reduce static charge, even if the physics wasn’t well understood. Pabst says that a lot of the recent findings “are not necessarily newer ideas, they are validating what we have taught in the industry for many years”. But he describes it as an exciting time, with science providing deep insight into industry knowledge.

Moisture content of the beans is another key variable, Hendon’s team found, with drier, darker roasts charging most strongly and therefore benefiting most from pre-wetting. The researchers also found that the right amount of water results in near-zero grounds being retained by the coffee grinder, again due to the reduced static charge.

They note that their findings have implications for waste reduction and drink quality. Hendon says that adding water during grinding allows you to reduce coffee mass by about 25%, while maintaining espresso concentration.

Pour-over science

Coffee is not just espresso.

Among the myriad of coffee-making techniques available, pour-over coffee is increasingly popular with enthusiasts due to its reputation for being better able to extract the unique characteristics of different coffee beans. A popular set-up uses a conical filter or “dripper” containing a filter paper, and the process is simple – you put coffee grounds in the filter, pour in hot water, and let the coffee drip out into a cup. There is a wealth of variables – such as grain size, water temperature and water speed – that allows whoever is holding the kettle to experiment and vary the process.

However, Arnold Mathijssen, a physicist at the University of Pennsylvania, has been studying exactly how they should be pouring that kettle (Physics of Fluids 37 043332).

As with an espresso, the challenge is to bring the water into uniform contact with every particle in the coffee bed. If the stream is too slow, for instance, it might run to the edges of the cone, flow through the filter paper and drain away without touching the grains in the centre.

To investigate how pouring technique affects this, Mathijssen and colleagues used a transparent glass cone similar in shape to a popular pour-over filter, and ultrathin filter paper. They then filled it with silica gel particles as a transparent model for coffee grains, and illuminated the set-up with a laser sheet while filming it with a high-speed camera.

The experiment revealed the importance of pour height for a static kettle. Pour from close range and the slow stream fails to effectively disturb the coffee bed. Lift the kettle to around 20 cm above the filter and something different happens. “We found that as you increase the height of the kettle this kind of avalanche dynamic emerges,” describes Mathijssen.

The increased energy in the stream enables it to dig deep into the coffee bed, suspending the particles and creating a hole in the middle. Particles around the side then slide into the centre and are themselves suspended, establishing a recirculating vortex (figure 4).

4 Avalanche dynamics

The stages of coffee grinds moving in a pour-over coffee set-up. First, a water jet starts to erode the coffee bed, causing the granules to become suspended and mixed into the water (left). These then accrete outwards towards the edge of the coffee bed (centre). The movement of granules from the bottom to the top edge causes the bed to collapse inwards (right), and the entire process repeats while the water jet continues.

“Every single particle in that cone is moving up and down through this vortex, so you get very nice and even extraction,” explains Mathijssen. “All of the particles see the water for an equal amount of time.”

But go too high, above about 30 cm, and surface tension breaks the stream into droplets – a process known as the Rayleigh–Plateau instability. The drops fail to dig deep into the bed, so the vortex does not form and coffee extraction falls. There is a sweet spot at a height of around 15–20 cm, Mathijssen says.

When the researchers switched back to coffee, they found that higher pours did indeed create stronger coffees with more total dissolved solids.

One cup at a time

These studies highlight a common theme. Decent coffee extraction is about creating uniform fluid contact with a porous medium that tends to be heterogeneous. And if it goes wrong, it is probably due to some failure of that uniformity.

As climate change squeezes yields and pushes prices higher, the coffee industry faces growing pressure to do more with less. Physics cannot protect vulnerable growing regions from drought and rising temperatures, but its insights can ensure that coffee is not wasted in the final seconds or minutes by a poorly prepared puck, a clumped grind or a lazy kettle lift.

“The best thing we can do,” says Hendon, “to be good custodians of any agricultural product is figure out how to use less of it so that more people can enjoy it.”

• Why not try our crossword inspired by this feature: “Caffeine kick: can you solve our crossword on coffee physics?“

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The “bumblebee” bat – a little animal weighing just 2 g – has inspired researchers to make the first palm-sized drone that can efficiently navigate in confined, dark and cluttered environments. The drone, which works using echolocation and operates on a milliwatt of power, could find applications in search and rescue missions in difficult-to-access spaces, say the researchers at the Worcester Polytechnic Institute in the US who developed it.

The bumblebee bat thrives in deep, dark caves and can perceive objects as small as just 0.1 mm thanks to ultrasound-based echolocation. The bat sends short chirps and then listens to the echoes produced as the sound waves bounce off surfaces. This ability is all the more astounding since the animal has only simple biosensory apparatus and just two million neurons.

The new drone, developed by a team led by Nitin Sanket, differs from existing autonomous aerial robots that require sophisticated sensors to work – including light detection and ranging (LIDAR), radio detection and ranging (RADAR), tactile sensors and infrared-based depth cameras, to name just a few. These complicated devices cannot easily be deployed in cluttered environments under difficult environmental conditions, such as fog, dust, smoke, low light and/or snow. This makes them unsuitable for search and rescue missions in disaster zones, where such conditions are often the norm.

Another major problem with existing robots, explains Sanket, is that they generate a lot of propeller noise, making echolocation difficult. “It’s like trying to listen to your friend while a jet engine is taking off next to you,” he says.

The new device, which is detailed in Science Robotics, employs a physical acoustic shield inspired by the ear cartilages of bumblebee bats to overcome this problem. In addition, the team used an artificial-intelligence (AI)-based neural network denoising framework to recover weak echoes from noisy signals.

New device works well in the wild

Ultrasonic sensing is insensitive to most environmental conditions, such as smoke, snow, dust and darkness, that are visually degrading and render light-based sensors like cameras or LIDARs ineffective. As such, they work very well in the wild, says Sanket. “This will allow this new class of robots to be readily deployed for search and rescue in real-world settings where conditions are dynamic, unpredictable and visually degraded, bringing us one step closer to deploying swarms of aerial robots to look for survivors.”

The researchers built their aerial device using standard off-the-shelf parts for motors, and flight- and electronic speed controllers. They custom designed a carbon fibre frame and 3D-printed other structural parts. The on-board computer is a Google Coral Mini development board and the ultrasound sensors are made by TDK Electronics and designed by team member Richard Przybyla. The robot measures around 16 cm across, costs roughly $400 and works using just 1.2 mW of sensing power.

The robot uses echolocation to determine obstacle locations in 3D using trilateration, explains Sanket. “This means that once it has found the obstacles, it plans a path around them to avoid them and go towards a goal direction (like North, for example).”

At the heart of the device is noise reduction using the physical shield and the neural network (dubbed “Saranga” by the team), which reduces noise by looking at echo signatures over time, in the same way as the bat’s neuronal signal processing system does. The researchers trained the network entirely in simulation and say that it can be adapted to the real world without re-training/fine-tuning.

Looking to nature’s experts

The idea for the project actually started out as a joke during Halloween of 2024, remembers Sanket, when he and his students wanted to build a robot that emerged from smoke for a video. “That film was much harder to make than we anticipated, and it turned into an obsession, forcing us to solve a real problem: how to make robots navigate in visually degraded/challenging conditions.”

“To find the answer, we looked to nature’s experts, bats, which not only live but thrive in damp, dark and dusty caves and can pinpoint something as thin as a human hair,” he explained.

In their experiments, Sanket and his colleagues had to study how bats deal with low signal-to-noise ratios. They found that bats change their cartilage stiffness to muffle noise and have peculiar nose-leaves (ridges on their nose) to modulate sound chirps. They based their physical acoustic shield on these structures.

According to the researchers, these highly-functional autonomous tiny aerial robots could be deployed in critical humanitarian applications such as search and rescue, cave exploration and combating poaching – tasks currently infeasible using existing aerial robots. “They could, for example,” says Sanket, “be sent into disaster areas where human or larger helicopter access is limited, thereby alleviating the challenges and pressures associated with saving lives.”

Looking ahead, the Worcester Polytechnic Institute team is now working to increase the robot’s flying speed and reduce its size even further. “We speculate that looking at novel forms of flight mechanisms is the key,” Sanket tells Physics World.

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By including weights associated with particles, researchers in the US, South Korea and Germany have generalized significantly the concept of hyperuniformity of multi-particle systems.

Hyperuniformity refers to a structural property in which at large enough length scales there is hidden order. Hyperuniform systems behave like they have no order at small length scales, similar to liquids, but at larger length scales they behave like crystals. This dual character leads to important applications for such materials, and the addition of weights allows for this characterization to extend to cases where additional properties of particles are included – such as a particle’s charge or mass.

The simplest example of a hyperuniform material is a crystal in which atoms or molecules are arranged in a uniform lattice that repeats in all directions. In addition to crystals, there are two classes of hyperuniform structures that are of great interest to physicists: quasicrystals and exotic disordered systems. Quasicrystals have highly ordered structures, but their patterns never repeat – so they are not true crystals.

Exotic disordered systems are of great interest to Salvatore Torquato of Princeton University, who was involved in this latest research on hyperuniformity. He tells Physics World that these systems are especially interesting because “they can behave like perfect crystals in the way they suppress large-scale density fluctuations and yet have characteristics of liquids or glasses at small length scales”.

Omnidirectional mirrors

From an engineering point of view, being both liquid-like and crystal-like is very useful. For example, crystalline materials will transmit light at specific wavelengths and incident angles and reflect light at others. In 2022, Torquato and colleagues showed that these optical “band gaps” should also exist in some exotic disordered systems, but without the restriction on incident angles. They suggest that this property could be used to create omnidirectional mirrors that operate only for light at certain wavelengths — unlike everyday mirrors, which reflect light at all wavelengths.

In their latest work, Torquato and colleagues have extended the theoretical description of hyperuniform systems by assigning “weights” to a material’s particle constituents. These weights can be scalar or vector properties. Examples of scalar properties include the charge or mass of a particle; whereas vector properties include the dipole moment or velocity of a particle.

Toraquato and colleagues discovered that under this more general framework of hyperuniformity, including weights can take a particle system which, without weights, is hyperuniform to one which is not (and vice versa).

Different atomic species

For example, one could begin with a standard hyperuniform system comprising identical particles and then imagine that the particles can have one of several different masses. In the real world this would describe a material made of several different atomic species.

The team’s work is important because it represents a significant expansion in the number and richness of systems that can be studied and potentially classed as hyperuniform. Furthermore, weighting provides engineers with additional degrees of freedom that could be used to fine tune hyperuniformity to create new and useful materials.

Torquato is hugely excited about future directions of this work: “Our generalization of hyperuniformity to weighted many-particle configurations opens up an immense set of problems. Our next steps will be driven by what we find to be the most exciting prospects”.

The research is described in Physical Review X.

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It might not seem obvious at first glance, but physics and finance have much in common – especially at the frontiers of quantitative analysis. Both fields use mathematics, data and computational models to tackle complex systems. Physicists are trained to build models that test hypotheses, all while embracing the idea of inherent uncertainty and a rapidly changing environment.

Financial markets are much the same, as they constantly change and evolve as data flows in, feedback loops are formed, and fast-paced decisions are made. As a physicist, there is a natural overlap between the skills that finance firms are looking for, and your academic training and abilities.

The idea of using physics to make sense of financial markets is not even that new. It has been around for over a century, with one of the earliest examples being attributed to French mathematician Louis Bachelie developing his “Theory of Speculation” in 1900, which used the concept of a random walk to analyse fluctuations in the Paris stock exchange.

Modern quantitative finance covers a wide range of subjects, all of which involve using mathematical and statistical methods. Most physicists can therefore adapt to working in this sector, provided they have some additional training. Traditionally, “quants” – quantitative analysts working across investment, markets, research and risk – get involved in option pricing and risk, requiring stochastic calculus, Monte Carlo techniques, and solving partial differential equations. Today’s quant roles more commonly involve supporting algorithmic or systematic trading; using data analytics, machine learning, and statistical and optimization methods.

Almost every one of these roles does require coding skills, especially when implementing models and algorithms in specific areas. Furthermore, the use of generative artificial intelligence (GenAI) to drive or enhance software development is now becoming standard. Physicists in the finance sector may also end up working as software developers, traders, risk managers and investment bankers.

To get a better idea of what it means to make this move from physics to finance, Physics World caught up with five professionals who went from the lab to the trading floor – some recently, some many decades ago. Antonia Lim, Ashreya Jayaram, Han Lee, Benjamin McRoberts and Sean Chang reflect on how their careers evolved, and explain the skills they carried over from physics. They also look back on the trade-offs they encountered along the way and offer advice to today’s graduates seeking to carve out their own careers in the sector.

Antonia Lim

Antonia Lim is chief investment officer (CIO) at global investment advisory firm Impact Cubed, which she joined in 2024. With 25 years of experience transforming investments and businesses, Lim began her career at Kleinwort Benson and Dresdner Bank (now Commerzbank), before going on to become global head of quantitative research at Barclays and then head of quantamental investments at Schroders.​ Lim holds an MPhys (masters of physics), specializing in theoretical and quantum physics, from the University of Oxford, UK. She is also independent chair of Weatherbys Private Bank’s investment committee and board advisor, and a member of the CFA Research and Policy Centre’s technical committee.​

I loved the four years I spent at Oxford, as well as the sheer intellectual breadth of physics: it trained me to move between abstract ideas, mathematical models and real-world questions, which is something that has stayed with me throughout my career. To me, physics is a wonderful mix of understanding how things really work, puzzles, maths and creativity.

The move into finance was not part of a grand plan. With hindsight, it started with my MPhys research project within a very popular part of the condensed-matter department, affectionately known at the time as the “Chaos Lab”, which was essentially the financial modelling department in physics. I was interested in the modelling and coding, and my dissertation focused on option-hedging strategies [techniques used to reduce investment risk] with transaction costs.

It was my first real exposure to the idea that methods rooted in physics could also be used within markets and decision-making under uncertainty. What appealed to me most was the modelling itself: taking a messy real-world problem, making sensible assumptions, and then testing how well the model works. After graduating, I ultimately chose to join a private bank because I thought it would be interesting and fun, though I was very close to accepting a role in defence engineering.

I’m now CIO at Impact Cubed, where we develop customized indices, analytics, tools and data capabilities with a strong sustainability focus. Although I do not use the specific content of my physics degree day to day, I use the methods and habits constantly: mathematical reasoning, structured problem-solving, comfort with complexity, and the discipline to test whether an answer is plausible before trusting it.

Physics also taught me to properly define a problem before trying to solve it. That sounds simple, but in finance it is incredibly important, whether you are building an index, designing an investment process, or challenging a model that is elegant mathematically but too far removed from the real world.

On the softer-skills side, physics gave me confidence in tackling unfamiliar problems and explaining technical ideas clearly. Over the years I have worked with people from many different disciplines, and one of the most valuable skills has been translating between technical precision and practical decision-making.

Finance can be intellectually stimulating because the problems are constantly evolving, and impact society at large. I’ve held the very serious responsibility of investing the livelihoods of millions of people. Within the quant sphere, there is a really strong community of people who enjoy models, evidence and rigorous thinking, so in that sense it can feel very familiar to physicists. Indeed, when I joined the London Quant Group decades ago, it felt like home straight away.

The pointy end of finance is shaped by market cycles and commercial pressure, which creates a degree of individual uncertainty that some can find draining. But if you enjoy solving practical problems and working at the intersection of theory, data and human behaviour it is an exciting place to build a career.

My advice to graduates looking to join finance today would be to not worry too much about making a perfectly linear plan. Physics gives you a very transferable toolkit, and there are already many physicists in finance, particularly in quantitative roles, so it is a move that can feel surprisingly natural.

Han Lee

Han Lee is co-founder of RLXPartners, a technology-startup venture consulting and investment firm. He has a PhD in theoretical physics from the University of Cambridge, UK, where he worked on quantum many-body problems in condensed matter. Lee has previously had numerous leadership roles in finance, most recently as global head of quantitative strategies and automated trading for the fixed income division at Morgan Stanley. Before that he was global head of quantitative analytics at RBS. 

When I started in the financial sector in the early 1990s, quantitative and mathematical finance was still a relatively new field, albeit one that was rapidly growing. It coincided with a major expansion of the financial markets, in particular the increasing complexity in financial derivatives. These changes provided many opportunities and challenges, which sounded interesting to me.

At the same time, the industry was actively seeking to find quantitative analysts with physics, maths or engineering backgrounds, which made the decision for me to move into finance straightforward. The sector still looks to hire physicists and those with a scientific background, but it has become much more competitive.

When it comes to skills from my physics background, both problem solving and scientific intuition are very transferable. Having the ability to harness familiar mathematical methods or programming techniques – or quickly learning new ones – to solve problems is a core component of the work. Physics also teaches a powerful combination of rigour when required, and an understanding of how and when to use approximations and estimations. Critical soft skills include communication and teamwork.

The pros and cons of a career in finance are straightforward. People are usually aware of very high starting salaries, especially in banking and hedge funds, as compared to staying in academia. Less well-known is how quickly this can increase once you progress and gain experience.

It can also be a very exciting and stimulating work environment, and can be very rewarding to see your work leading directly to results that have immediate impact. Potential challenges or downsides are that there is a relatively intense and competitive working culture, which can bring stress and some uncertainty; which won’t suit everyone.

Furthermore, not all physics graduates and postgrads might want to move to a completely different field. Although finance can have interesting and complex problems to work on, the focus is quite different from working in academia. The latter would allow for a much higher degree of intellectual freedom, and some would consider this not only intrinsically valuable but also capable of having a significant and wider positive impact.

Ashreya Jayaram

Ashreya Jayaram is a quantitative strategist in the corporate and private bank division of Deutsche Bank. She did her PhD in physics at the Johannes Gutenberg University of Mainz, Germany, focusing on the theory of biologically-inspired nonequilibrium systems. After a postdoc at the University of Stuttgart, Jayaram moved to a career in quantitative finance at Wells Fargo, before taking on her current role at Deutsche Bank.

My decision to move from physics to finance came when I realized I was not suited to an academic career and instead I began looking out for options in industry. I was looking into avenues where I could continue to build useful models that capture real-world observations, which was a part of my academic career that I most enjoyed. This led me to quantitative finance.

To understand if quantitative finance was my cup of tea, I used online resources to educate myself about financial markets and the kind of models practitioners use to describe them – and here I am today. A key skill that I developed during my physics degree that is applicable in my job now is the ability to break down complex problems into simpler and more tractable forms. It’s also important to identify the vital elements that drive the behaviour of observables of interest (for example, profits) – a skill that is systematically developed in theoretical physics.

Another useful skill is the ability to manage multiple projects simultaneously with different collaborators. I also have to communicate effectively with diverse audiences of varying backgrounds, which is an ability I developed during the course of my PhD and I believe helps me in my current role.

What excites me most about my job today is the dynamic and unpredictable nature of financial markets. Their far-reaching impact on everyday life creates a high-energy work environment, which I find both engaging and enjoyable.

If you’re looking to move into the field, my advice would be to find out more about the different roles in the financial world and the diverse range of skills they demand. For physicists with no exposure to finance, it would beneficial to read about what you might enjoy working on, and look into some self-formulated projects and internships to see if it does align with your interests.

Benjamin McRoberts

Benjamin McRoberts is head of European power engineering at Citadel. He spent the last decade working at Goldman Sachs, most recently as the head of EMEA Commodities Strats. McRoberts studied mathematics and physics the University of Bristol in the UK. He also completed an MSc in financial mathematics at the University of Warwick.

During my BSc at Bristol, I realized pretty early on that I preferred the theoretical side over the practical, and I switched to the joint honours MSci mathematics and physics course after my first year. This allowed me to replace some of the experimental physics courses with more of a mathematical physics focus so I could study concepts such as applied partial differential equations, fluid dynamics and quantum information theory.

My final year master’s dissertation focused on the “weak measurement” quantum mechanical phenomenon, and while I explored the idea of doing a PhD after my master’s, I ultimately fancied a change of scenery. I also found the open-ended nature of pursuing further academic research a little bit daunting, and I wasn’t ready to commit another four years or so to something I wasn’t totally sure about.

I had a sense that finance might provide some interesting quantitative problems that I could use my educational background for, and I was likely influenced by a careers fair hosted by my university. I did consider a few other avenues such as technology consulting and teaching, but ultimately the large annual graduate intake for investment banking in London appeared to provide the most opportunity.

After applying for a series of summer internship programmes at the end of my third year, I secured an offer from the Australian investment bank Macquarie. That summer I worked within their infrastructure funds business, which raised investment capital from large asset managers and pension funds, investing it in infrastructure projects across Europe, such as airports, toll-roads and utilities. That internship led to a full-time graduate offer that I gladly accepted, kicking off my graduate career in finance.

I worked at Macquarie for a year but decided to build my skills with a master’s in financial mathematics at Warwick. While I was contemplating if this was the right path for me, I read a book by particle-physicist turned quant Emanuel Derman, titled My Life as a Quant: Reflections on Physics and Finance. It really captivated me and I still highly recommend it, especially for those with a physics background considering a career in finance.

During that degree, I built on some of the basics of probability and statistics I’d learned on my undergraduate course, to cover new topics like stochastic calculus and derivatives pricing. I also got more of a taste of computer programming, through a module focused on C++ which I really enjoyed. I quickly realized that I had made a good career choice by going back to university.

After leaving Warwick, I spent two years as a quantitative analyst at a commodities trading firm before joining Goldman Sachs in their “commodity strategies”  group in London. Over the last decade I’ve worked across their commodities complex – from precious and base metals to power and gas, and oil products – covering derivatives pricing/modelling, trading tools and analytics, as well as automated trading.

Last year, I had the opportunity to join the US-based multinational hedge-fund and financial services company Citadel. I was extremely impressed by the calibre of people I met during the interview process, and similarly since joining the company. This, together with the firm’s reputation for its rigorous and sophisticated investment approach, gave me the confidence that it was the right move for me.

Since finishing my master’s, I’ve consistently made use of my technical educational background. Sometimes that’s been explicitly – using skills from linear algebra, calculus and differential equations – but sometimes indirectly from generally learning to be better at abstract problem solving and not giving up when faced with a difficult intellectual challenge.

What I’ve loved the most about working in the commodities markets is having the ability to use sophisticated mathematical techniques to solve problems in the real world. On the flip side, it’s a demanding and fast-paced environment, which requires commitment and tenacity to succeed.

What has sustained me throughout is a real passion and enjoyment for what I do. You typically get to work with a group of talented and motivated individuals. There is a strong feeling of camaraderie and shared pride in your work, which is something I’ve always appreciated.

For physics graduates looking to get into the finance, remember that physicists typically make great quantitative finance professionals. I’ve worked with and hired many and they tend to do very well – partly thanks to their willingness to find creative and varying solutions to any problem. Your formal scientific training coupled with an appreciation for a whole swathe of real-world applications gives physicists a fantastic foundation for such a career.

• For more careers inspiration take a look at the Physics World Jobs hub.

The post Trading places: meet the physicists-turned-analysts who are driving the frontiers of finance appeared first on Physics World.

Gwenaëlle Lefeuvre studied physics at Sorbonne Université in Paris, France, before moving to Université Paris Cité to do a PhD in experimental particle physics. After postdocs at Syracuse University in the US and the University of Sussex in the UK, she left academia and worked for 10 years at the UK company Micron Semiconductor Ltd. Here, Lefeuvre set up a business unit dedicated to designing and manufacturing CVD diamond sensors.

Lefeuvre now works as the network coordinator for Photonics Bretagne – a non-profit association in Brittany, France. As an innovation hub, the organization supports the development of the photonics ecosystem across industry, research and education in Brittany, and helps integrate photonics technologies into other sectors.

What skills do you use every day in your job?

When it comes to skills I need for my role, my scientific background is just the starting point. I am the contact point between the Photonics Bretagne team, our members, our European partners, and any other parties interested in what photonics have to offer. While my background gives me credibility, what I really use is the inquisitive spirit that a physics education imprints in us. I ask a lot of questions, all the time and to everyone, so I can better understand what people work on, what they need, and how their products can be used in different situations.

Of course, this means that communication and networking are also crucial. Representing my member companies, for example, means that I must be able to translate what they are offering so it’s understandable for people who might work in a very different sector, such as mobility, agriculture or cosmetics.

Finally, being flexible is a must. I wear different hats depending on the task at hand, and need to be able to switch them around quickly.

What do you like best and least about your job?

I love many aspects of my role, but top of the list is having the opportunity to keep learning about new technologies and applications. The breadth and depth of knowledge my co-workers and our members possess is as humbling as it is inspiring. While I am more of a “generalist physicist” myself, I have worked on many different types of experimental systems so can appreciate the expertise at play.

I also enjoy the diversity of my work, which makes my days fun and varied. I might be meeting with members and looking for ways to support them; organizing a delegation visit with my European partners; or advocating for photonics in cross-sector events – and that’s just naming a few of my responsibilities. There is never a dull day.

With the diversity of my role and my enthusiasm to find out more comes the challenge of prioritizing. There are so many things I would love to be doing, but we are a small team and we must focus our efforts on those actions that can best serve our community. And of course, the administrative and reporting tasks are never loved by anyone and take up more valuable time than I would like. They are a constant in every job though, and can be managed through good planning.

What do you know today, that you wish you knew when you were starting out in your career?

Three things come to mind. The first is that it’s helpful to know whether you will enjoy becoming a highly specialized researcher, or if you would thrive in a more general role. Higher education in physics is designed around gaining a finer and finer degree of specialization. I realized during my postdocs that I was not enjoying staying in one given field (neutrino physics, in my case) as much as I expected to. What I loved was working hands-on with different types of sensors, which is a more transversal specialization, so to speak. Not everyone is built to be a specialist and there is nothing wrong with that. Many career options are open to those who embrace remaining curious about everything, provided they have a strong background to back it up.

There are so many ways to work in, with or for the physics community – the main limiting factor for my younger self was probably my own imagination

Secondly, it’s worth remembering that people change, and ambitions do too. It has been said many times in this column, but life isn’t linear and neither is a career. It is important to account for the person you will become, so that you don’t make choices today that will make your future self unhappy or stuck. There are so many ways to work in, with or for the physics community – the main limiting factor for my younger self was probably my own imagination. Luckily, many degrees now include broadening experiences like semesters abroad or entrepreneurship classes.

Finally, I wish I had realized earlier that people love it when we ask them questions about their work. Doing so does not showcase our ignorance but our interest – it’s a true win-win.

The post Ask me anything: Gwenaëlle Lefeuvre ‘Not everyone is built to be a specialist and there is nothing wrong with that’ appeared first on Physics World.

Experience of RTsafe succeSRS/SBRT implementation for Varian Halcyon machine.

This presentation focuses on the implementation of end-to-end dosimetry audits for SRS/SBRT treatments using the RTsafe independent audit system on a Varian Halcyon machine.

SRS/SBRT are advanced radiotherapy techniques that deliver very high ablative doses of radiation, with great accuracy, precision and conformality. As we know, in radiotherapy, even small errors in the acquisition of CT images for simulation, in planning, dosimetry, treatment delivery, or patient positioning can lead to negative consequences.

Given the high-dose gradients and submillimeter accuracy required in stereotactic radiotherapy, the audit evaluates the entire treatment chain – from imaging and target definition to planning, delivery and dose verification. The role of such audits in detecting geometric and dosimetric uncertainties is highlighted, along with their contribution to ensuring treatment accuracy, consistency and patient safety in high-precision radiotherapy. Last but not least, especially at the beginning of the implementation of these techniques in a new radiotherapy department, the audit can also help to validate the specific procedures for SRS/SBRT and the professional training for the members of the treatment team.

Florin Costache is a medical physicist expert in radiotherapy across multiple clinics, while also serving as a radiation safety officer, with more than 20 years of professional activity in clinical and academic environments. Throughout his career, he has worked in leading radiotherapy centers in Romania, contributing to commissioning, quality assurance, dosimetry and advanced treatment planning using modern systems such as Varian platforms. Florin’s expertise spans advanced radiotherapy techniques, radiation safety and the implementation of quality assurance systems in clinical practice.

In addition to his clinical work, Florin is a lecturer, course coordinator and former president of the Romanian Medical Physics Society, with numerous scientific publications and conference presentations.

The post End-to-end dosimetry audit for SRS/SBRT: optional or mandatory at the beginning of the journey? appeared first on Physics World.

Newton’s and Einstein’s theories of gravity apply across distances of hundreds of millions of light–years. That is the conclusion of an international team of scientists, whose measurements of the gravitational acceleration of galaxy clusters have been made over the largest distances ever studied.

The study supports the Standard Model of cosmology, which invokes the gravitational effect of dark matter to explain the large-scale structure of the universe. As a result the team claims that its observation is at odds with alternative theories of gravity such as modified Newtonian dynamics (MOND).

“We’re seeing a clear pattern: these alternative models of gravity are running out of room to manoeuvre,” the study lead, cosmologist Patricio Gallardo of the University of Pennsylvania in the US tells Physics World.

However, an astronomer who studies MOND argues that the result – and the conclusion – is not clear cut. “I’m not convinced that they’re testing MOND,” says Stacy McGaugh, a professor of astronomy at Case Western Reserve University in the US.

Vast distances

The debate revolves around dark matter, which is a hypothetical substance that the majority of astronomers believe is responsible for the “extra gravity” observed in the universe that cannot be explained by the presence of visible matter alone. But the evidence for dark matter is circumstantial and this leaves room for theories such as MOND – which suggests that a small modification to gravity at low gravitational accelerations precludes the need for dark matter.

To probe the nature of gravity over large distance scales, Gallardo’s 40-strong team measured the gravitational acceleration between pairs of galaxy clusters (pairwise clusters) separated by distances ranging from about 100–750 million light–years.

They used the kinematic Sunyaev–Zel’dovich (kSZ) effect to provide information on the motions of the clusters. This involves the cosmic microwave background (CMB) radiation, which comprises photons left over from the Big Bang. As these microwave photons pass through a galaxy cluster, they scatter off free electrons and receive an energy boost that the team detected using the Atacama Cosmology Telescope in Chile.

Gravity tends to pull these clusters together and this Doppler shifts the kSZ energy boost. This subtle effect was detected for the first time in 2012.

A statistical method called the pairwise kSZ estimator determined the average infall velocity of cluster pairs.

Clean comparison

“This estimator gives us a clean way of comparing the theoretical predictions made by cosmologists of the pairwise accelerations under the influence of gravity,” says Gallardo.

Gravitational acceleration on the length scale of interest was then determined by combining the infall velocity observations with the distribution of galaxies as mapped by various surveys. They found that gravity follows an inverse-square law with regards to distance, just as predicted by the gravitational models of Newton and Einstein.

Gallardo argues that if MOND is correct, then the observed fall in gravitational acceleration would not be as steep as the inverse square.

“Even if an alternative theory of gravity predicts the distributions of galaxies, it will still fail to predict the pairwise velocities without introducing a component of invisible dark matter,” says Gallardo.

However, not all astronomers agree with this conclusion.

“It appears that they’ve worked out what they expect conventionally, then projected this onto what they imagine MOND would do, [but] it isn’t actually a MOND calculation,” says McGaugh.

Galaxy distributions

McGaugh questions how well the pairwise velocities can be isolated from the gravitational tugs of all the other galaxy clusters around them.

Gallardo counters, “It is right that everything pulls on everything, but that is precisely the beauty of this technique”. At its basis is the correlation function of galaxies, which describes the probability that two galaxies will be within a given distance of each other. At its the heart is the distribution of matter in the universe, as laid out in the Big Bang and described by the Standard Model of cosmology.

“If clusters are too close to each other, then the details of how they are placed will matter, but as distances grow and the universe looks more and more isotropic, the averages tend to smooth out and the equations governing the evolution of the distribution of matter take over,” says Gallardo.

McGaugh argues that something else, called the external field effect, happens at large distances. This is a concept in MOND where the gravitational acceleration produced by all the other objects in the universe is non-negligible and can affect smaller systems, such as a pair of galaxy clusters.

Background acceleration

“Once one gets far enough out, this takes over when the background acceleration of everything else is greater than that between any two objects,” McGaugh says.

McGaugh cites a paper in The Astrophysical Journal on which he was co-author. It describes how the gravitational acceleration field in the local universe can be calculated from the known distribution of galaxies. He describes that field as “a mess” and that the approach of Gallardo’s team averages over the subtleties.

Nevertheless, Gallardo remains bullish. “When we look at different scales and tracers of the gravitational potential such as anisotropies of the CMB, the polarization of the CMB, the baryon acoustic oscillations, the lensing of the CMB and galaxy lensing, they all seem to favour the existence of dark matter and disfavour modifications of gravity,” he says.

However, MOND has its own accomplishments, such as being able to predict the gravitational acceleration curves of galaxies, explain the plane of dwarf galaxies found around the Milky Way and Andromeda galaxies, and even the orbits of wide binary stars. But while Gallardo acknowledges that MOND “has partial successes in some regimes,” it “fails to provide a unified and consistent view of how gravity influences the history of the universe.”

In response McGaugh feels that crucial elements of MOND are being papered over and ignored.

“They’re basically reinventing the wheel without knowing a better wheel was already in the literature,” he says.

Gallardo and colleagues report their results in Physical Review Letters.

• Keith Cooper has written a series of articles about dark matter and alternative theories of gravity.

The post Newton’s law describes gravity on cosmological scales, galaxy clusters reveal appeared first on Physics World.

Fancy some more? Check out our puzzles page.

The post Quiz of the week: at what temperature did researchers find a new critical point in water? appeared first on Physics World.

You might think that a bee’s stinger, a rose’s thorn or a razor-like animal tooth has a sharp pointed tip, rather like “cone-shaped” needles used for injections. Yet a closer look finds otherwise, and these objects are usually rounded at the tip, curving gently like a parabola.

Why this is the case is a mystery and it was thought that it was the result of convergent evolution, in other words different species independently arriving at similar solutions.

This is partly because a rounded curve penetrates skin better as it distributes forces more evenly throughout the tissue. The rounded shape is also less prone to breaking than a perfect cone.

Physicist Kaare Hartvig Jensen from the Technical University of Denmark (DTU), however, was not convinced by the evolution argument. “There is a general notion that almost everything in nature exists for a reason,” he says. “But if you look at an unused tooth, it does not necessarily have [a rounded] shape, and if you observe the shape later in the organism’s life, the parabola will emerge.”

Jensen thought that simple mechanical wear might be behind the effect, and so with his DTU colleague John Sebastian, they went about testing this hypothesis.

To do so they were inspired by industrial durability testing where a robot sits on a chair every few seconds to test its robustness, for example.

Their set-up involved a plate atop a vibrating machine containing a number of objects. “Initially, I attempted to build a device using sharpened chalk, but it produced a lot of dust,” he told Physics World. “Ultimately, I settled on pencils.”

They sharpened the pencils as stand-ins for their biological counterparts and put them on the plate for over four hours as they constantly collided with each other. The team also carried around pencils in a small box in their pockets for several days, again to expose them to random collisions and movements.

They found that no matter how sharp the pencils were to begin with, their tips always developed the same rounded parabolic shape.

“This points to something more fundamental: that random processes in and of themselves can lead to a universal form,” adds Jensen. “The parabola is a stable shape across scales, from a thorn to an elephant’s tusk. The tips are thus not necessarily designed perfectly from the start – they become so through random wear.”

Jensen admits that – rather than in the isotropic case with pencils – most real biological materials have some structure to them, being stronger in one direction than another.

“I would like to explore what shapes result from random wear on these structured materials,” adds Jensen. “Perhaps we can start with something like nails – sharp right after cutting, then gradually blunting. Exactly how this occurs would be of interest.”

The post Study reveals the physics behind nature’s pointed tips appeared first on Physics World.

Medical physics – the application of physics principles and techniques to medicine – plays a pivotal role within modern healthcare, with advances in the field serving to improve diagnostic accuracy, treatment precision and patient safety. But despite its immense potential to enhance patient care, medical physics in the UK faces various funding, regulatory and approval challenges that may prevent it from fulfilling this promise.

Taking a closer look at these obstacles, the Institute of Physics (IOP) has published a new community perspective report entitled Medical Physics in the UK: Opportunities and Challenges. The report examines the barriers to translation and commercialization of medical physics research, and proposes the next steps towards creating a more supportive environment for medical physics in the UK.

The report was instigated by the IOP Medical Physics Group and presents the conclusions of a series of discussions, held over two months, examining the challenges that medical physicists encounter in their daily work. The report also highlights the outcomes of an intensive two-day workshop examining the translation of quantum technologies into clinical applications.

The challenges and the opportunities

The UK has a strong legacy of leading medical physics research. To benchmark its contributions, the report authors analysed the top 5% most highly cited papers published in international medical physics journals from 2014 to 2023, revealing that the UK is fourth in the world for its research output in medical physics.

The UK also boasts a large, diverse medical technology industry and has the sixth largest medical device market globally. Notably, its research output involves a high proportion of non-academic co-authors – including corporate, government and clinical collaborators – suggesting a strong potential for translating physics research into the medical market.

The report identifies some of the challenges in realising this potential, including a stretched workforce and critical skills shortages, and outlines some of the more impactful obstacles – namely misaligned funding structures, a complex regulatory landscape, and lengthy approval processes for medical devices and clinical trials.

In the UK, medical physics research is funded by a combination of government agencies, charitable organizations, and independent trusts. The multidisciplinary nature of medical physics, however, risks promising projects falling into the gaps between funding categories, making it difficult for researchers to secure financial backing.

Navigating the regulatory landscape for medical physics developments is also a complex process, with different global markets having their own specific requirements. Challenges here include obtaining initial regulatory approval, adapting to evolving standards and managing multiple regulatory bodies simultaneously. And while new technologies are often sold into larger markets such as the USA and Germany, the UK’s medical device approval process lacks seamless integration with international regulatory bodies, creating barriers to such wider market adoption.

Finally, clinical trials and validation processes for medical physics innovations can often take several years. Securing funding for large-scale trials and collecting sufficient data to demonstrate long-term efficacy can also lead to delays in introducing new technologies to patients.

Overcoming these challenges will be key to fully exploiting the significant potential of medical physics to revolutionize healthcare in the UK. An initial step could be to bring together this diverse community – including researchers, medical practitioners, industry, NHS officials, government representatives and funders – to initiate a collaborative dialogue and brainstorm innovative strategies.

The report suggests three possible discussion points: how to better align funding mechanisms to support interdisciplinary research; how to shape an integrated regulatory framework with increased transparency; and how to strengthen collaboration between academia, healthcare and industry.

Such discussions should result in a comprehensive list of actionable recommendations. The report authors propose that the IOP establishes an impact project to explore the details of these recommendations and identify pragmatic, implementable solutions for their implementation.

The post Report highlights challenges and opportunities for UK medical physics appeared first on Physics World.

By harnessing the unique properties of tantala (tantalum pentoxide), a team of US-based researchers has created a photonic integrated circuit that can be tuned to deliver laser light across a broad spectrum of visible and infrared wavelengths.

The work was done by researchers at the National Institute of Standards and Technology (NIST) and colleagues at Octave Photonics.

From consumer electronics to atom-based metrology systems, many modern technologies depend on sources that deliver light at specific wavelengths. However, delivering high-quality narrow-band light is difficult – especially at visible wavelengths. As a result many of these technologies cannot be miniaturized to create low-cost, portable devices. Instead they must be implemented in bulky tabletop setups that are operated in expensive laboratory settings.

“Photonics technology offers routes to miniaturize components like laser sources and switches to the chip scale – devices smaller than a grain of rice,” explains study leader Grant Brodnik . “Different photonic materials have different strengths and limitations, and there is currently no single material ecosystem that can accommodate all the diverse demands of photonics.”

Mismatched materials

One promising solution involves integrating multiple advanced materials into the same device, harnessing combinations of their photonic properties to engineer capabilities that would not be possible with any single material. The key challenge is that many photonic materials have mismatched thermal, mechanical, and chemical properties, making them broadly incompatible with one another. So far, this has prevented researchers from seamlessly combining multiple materials into chip-scale devices.

To address this challenge, Brodnik’s team looked to the unique properties of tantala. A key feature of the material is that it can transform laser light at one frequency into laser light within a broad spectrum of light at visible and infrared wavelengths.

Tantala can be deposited onto other materials at room temperature, before being annealed at relatively modest temperatures of around 500 °C. In comparison, more conventional materials such as silicon nitride require annealing temperatures approaching 1200 °C.

Once deposited, tantala benefits from low internal mechanical stress, at around 38 MPa compared with around 800 MPa for silicon nitride. Together, these properties make it compatible with a broad range of underlying substrates and structures without damaging devices during fabrication.

In this latest work, Brodnik and colleagues deposited tantala directly onto a patterned thin-film substrate of lithium niobate – which itself an advanced photonic material. The result is a monolithically integrated, 3D photonic platform.

Sprinkling tantala

“We essentially sprinkle tantala directly on top of existing photonic circuitry,” Brodnik explains. “Then, we can make new photonics circuits on top, link other circuits below, or even operate together with the underlayer material and devices for new functionality.”

The team then showed that their combined platform is capable of a range of useful capabilities. “We demonstrated various photonic functions that involve generating new, custom-colour light sources from single-colour input lasers,” Brodnik says. “We also made frequency combs and supercontinuum, which are important tools for things like optical communications, precision metrology, and sensing applications.”

Several of these devices relied on the tantala and lithium niobate layers working in tandem. For instance, they used tantala to generate intense laser pulses, before passing light into the lithium niobate layer for further nonlinear processing. This allowed them to precisely measure the frequency of the laser light.

The work points to a new and broadly applicable route to the 3D integration of photonic materials, which could make it far easier to link advanced photonic functions across existing platforms.

In turn, this could open new pathways towards the scalable, affordable fabrication of complex photonic circuits, applicable in real-world devices. “New configurations offer opportunities to realise entirely new photonic designs that will drive lab experiments to field-deployable systems,” Brodnik says.

The research is described in Nature.

• This article was updated on 12 May 2026 to recognize the contributions from researchers at Octave Photonics.

The post Tantala 3D integrated circuits deliver a rainbow of laser light appeared first on Physics World.

Here’s how the game works:

1. 1. Enter a word guess – in this game the word has six letters.
   2. After submitting your guess, each letter in the guessed word is coloured to provide feedback:
      • Green: The letter is correct and is in the correct position in the target word.
      • Yellow: The letter is correct but is in the wrong position in the target word.
      • Grey: The letter is not in the target word at all.
   3. Using this colour feedback, refine your next guess.
   4. Continue guessing until you correctly identify the hidden word(s) or run out of attempts.

If you need any hints, read this recent article.

Fancy some more? Check out our puzzles page.

The post Word wave puzzle no.3 appeared first on Physics World.

The quantum-technology sector is burgeoning, but challenges remain when it comes to creating viable commercial products. While quantum sensors show great promise, some technologies rely on ultrahigh vacuum (UHV) – which is difficult to achieve in compact, portable devices.

My guest in this episode of the Physics World Weekly podcast is Florence Concepcion, who focuses on the miniaturization of UHV systems for practical quantum sensors and other devices. She is a senior quantum engineer at Aquark Technologies – a UK-based company that is developing cold-matter quantum technologies.

In 2025 Concepcion was awarded a £1.9m Innovate Future Leaders Fellowship by the UK government. She explains how that money will be spent over four years to develop vacuum systems for quantum technologies.

Before joining Aquark, Concepcion did a PhD on a topic at the intersection of astronomy and atomic physics. She talks about her transition from academia to industry and we chat about careers for physicists in the quantum sector.

The post Quantum sensors benefit from miniaturized ultrahigh vacuum appeared first on Physics World.

In scientific terms, fission and fusion are two sides of the same coin. The first produces energy by splitting big atomic nuclei into two or more pieces. The second produces it by combining two or more small nuclei into a larger one. In both cases, the difference between the mass you start out with and the mass you end up with determines how much energy you get, following Einstein’s famous equation E=mc².

Practically speaking, though, fission and fusion are worlds apart. Fission power plants have been putting electrons on the grid since the 1950s. In 2024, they produced around 10% of the world’s total electricity – less than coal, gas or hydropower, but more than wind and solar.

Fusion power plants, in contrast, do not exist yet. Although the US National Ignition Facility (NIF) can generate more energy from a pellet of fusion fuel than it delivers to the pellet, not even its biggest fans would mistake it for a power plant. A Europe-based fusion experiment, ITER, remains under construction after years of delays. And so far, the private fusion companies that have sprung up in recent years have only designs, not working devices, to show for their efforts.

It’s an interesting question, then, why the vibes at last week’s Fusion Fest – which took place on 14 April in London, UK – were so much better than those at the Nuclear Summit held the next day in the same location. Both events took place under the auspices of The Economist newspaper. Both featured experts from finance, government, academic and policy circles. So why was the fusion gathering so bullish, and why was the fission one so downcast?

Fusion is having a moment

If you believe the speakers at Fusion Fest, they are optimistic because, after decades of being – as the old gibe has it – permanently 20 years in the future, fusion energy is finally ready for its close-up. “We are, I believe, at a pivotal moment in the field, and it’s a very exciting time to be in it,” Tim Bestwick, the interim chief executive of the UK Atomic Energy Authority (UKAEA), told the crowd at the opening session.

Later that day, a subsidiary of UKAEA, UK Fusion Energy Ltd, unveiled its strategy for building a pilot fusion power plant. Known as the Spherical Tokamak for Energy Production (STEP), it is receiving £1.3bn in UK government support and is scheduled to begin operations in 2040.

Other fusion organizations are promising results on even shorter timelines.  A start-up called Pacific Fusion has pledged to build a power plant based on inertial fusion by the mid-2030s. Another company, Proxima Fusion, has a 2035 target for its stellarator-based technology. A third, Commonwealth Fusion Systems, is building a tokamak-style reactor that will, it claims, generate its first plasma (though admittedly not its first net energy) next year.

The spokespeople for these firms (and many others) have a strong incentive to be optimistic. They’re trying to attract funding, and in most cases, they’re relying on notoriously impatient venture capitalists rather than nations like the UK (and, on a far bigger scale, China) that can afford to take a longer view. A certain amount of pie-in-the-sky thinking is to be expected from them. Yet when The Economist’s global energy and climate innovation editor, Vijay Vaitheeswaran, asked a more diverse pool of attendees to predict when fusion would become cost-competitive with solar, the most popular choice was “within 20 years”. It certainly wasn’t “never”.

Bumps on the road to limitless energy

A few Fusion Fest speakers did mention some potential pitfalls. One area of concern is that suppliers of key components – high-grade optics for laser fusion, high-temperature superconducting wire for magnetic fusion, and so on – do not yet have the capacity to support a growing fusion sector. This is a financial problem as well as a technical one. Jeff Lawson, the chief executive of Inertia Fusion, warned the audience that fusion will only succeed commercially if it follows the example of solar power by using components manufactured cheaply and at scale. Otherwise, he said, it risks becoming more like nuclear fission, characterized by expensive, bespoke facilities.

In a similar vein, several speakers suggested that it would be a serious setback for the field if fusion – which produces far less radioactive waste than fission, carries no risk of meltdown and does not use materials that can be repurposed for nuclear weapons – ends up bearing the same regulatory burden as fission reactors. Indeed, one audience member drew murmurs of agreement by asking whether fusion experts should avoid using the word “reactor”, to remove any associations with fission nuclear power.

Nuclear’s (new) new dawn

With fusion’s enthusiasts promoting it as the clean, safe nuclear energy of the future, it’s easy for fission to get cast as the waste-producing, meltdown- and proliferation-prone nuclear energy of the past. Yet there are reasons to be optimistic about fission’s prospects, too. Recent increases in energy demand have triggered an uptick of interest in low-carbon baseload power. So, too, has the Iran War and the closure of the Strait of Hormuz, which threatens the world’s supply of fossil fuels in a way that hasn’t happened since the 1970s. Back then, France responded by building 57 new fission reactors. Could it happen again?

Charles Oppenheimer certainly thinks it could. The grandson of atom bomb pioneer J Robert Oppenheimer, he is the founder and chief executive of Oppenheimer Energy, which aims to accelerate reactor deployment. At the Nuclear Summit, Oppenheimer argued that “economic tailwinds” are producing a burst of optimism about nuclear power, as new concerns about energy security join older ones about climate change. But even he couldn’t avoid sounding a note of caution. “Institutional capital does not look at nuclear as an investible product,” Oppenheimer warned. “It looks at it as a field with a bad track record.” To counter this view, he argued, “we need to get something going to justify the optimism.”

Small reactors could be huge…

For many attendees, that “something” is small modular reactors (SMRs). Because they are designed to be somewhere between the size of a shipping container and a house, the idea is that SMRs could be assembled by the hundreds in factories, rather than constructed on-site in ones and twos. This would save time and money, which is essential in an industry with a reputation for high costs and long delays.  As Tim Stone, a former chair of the UK Nuclear Industry Association, put it, the nuclear industry needs to treat “construct” as a dirty word: “Anyone who says ‘construct’ has to put £5 in the swear box,” he said.

SMRs promise other benefits, too. Their small size makes them less prone to catastrophic meltdowns, and they are poorly suited to producing material for nuclear bombs. For these reasons, some speakers expressed hope that they could be regulated like research reactors, not power plants. That would ease the burden on developers and further reduce the time required to constr – sorry, manufacture – them.

Another advantage of SMRs is that in principle, they can be installed in places where large-scale power plants would not make technical or economic sense. For example, the UK firm Cambridge Atomworks is developing a 5 MW SMR that is designed to supply power to mines in remote locations. According to its chief executive, Ian Farnan, such a reactor could compete with diesel generators on logistics and environmental considerations as well as price.

More promising still – at least from an investor perspective – is the prospect of using SMRs to power AI data centres. The largest such centres can consume as much as a gigawatt of electricity, and their developers are increasingly looking off-grid for ways of powering them. They also have stringent uptime requirements (the industry standard is “five nines”, or 99.999% availability) that make them awkward for variable energy sources such as wind and solar. With local communities unsurprisingly objecting to data centres that run on noisy, polluting gas generators, SMRs are an attractive alternative. “If you want clean, firm, reliable and shit-tonnes of power, it’s got to be nuclear,” summarized Amy Roma, a lawyer and nuclear energy policy expert at the law firm Orrick.

…but maybe not right away

Despite these developments, though, an SMR-led fission revival is far from guaranteed.  James Walker, the chief executive of the SMR firm Nano Nuclear Energy, drew pained laughter from the audience when he declared that the problem with small modular reactors is “they’re not small and they’re not modular”. Robert Rudich, the chief business development officer at another SMR firm, CGE, agreed that this is something the industry needs to work on. “If we don’t bring [reactors] to a place where the private sector can help, we’re not going to get there,” he said. On the policy front, Najat Mokhtar, the deputy director general of the International Atomic Energy Agency, isn’t sure that regulators will go easy on SMRs. “The technology is evolving fast and the regulation and licensing is not,” she warned.

With a technology that faces such knotty problems, it’s easy to be pessimistic. But it’s also easy to be optimistic about a technology that hasn’t matured enough to run into similar difficulties. This is the main reason for the different moods within fusion and fission. Though the fusion community may see the nuclear industry as a model of what not to do, many nuclear experts return the favour by regarding fusion as vapourware promised to gullible investors on impossible timelines. Will technical advances, climate concerns and the rising tide of world energy usage come together in a way that proves both sets of doubters wrong? Perhaps a future Fusion Fest and Nuclear Summit will hold the answers.

• This article was amended on 23/04/2026 to update Amy Roma’s affiliation and on 27/04/2026 to correct the nature of Pacific Fusion’s power-plant concept.

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Almost 1400 people, including two Nobel laureates, have signed an open letter condemning the US/Israeli attacks on Iranian academic institutions. The signatories call on the international community to “protect scientific infrastructure, defend academic life, and uphold the principle that knowledge-serving institutions must never be treated as expendable in war”.

The letter, which is addressed to the United Nations secretary-general, the director-general of UNESCO, the UN High Commissioner for Human Rights and “the governments of all parties to the conflict”, was instigated by the theoretical condensed-matter physicist Alireza Qaiumzadeh and colleagues from the Norwegian University of Science and Technology.

The signatories, which include May-Britt Moser and Edvard Moser who shared the 2014 Nobel Prize in Physiology or Medicine, express their “grave concern” over the attacks that they say have “damaged laboratories, universities, hospitals, and other scientific institutions”.

Organizations that have been attacked include Isfahan University of Technology, Iran University of Science and Technology and the Pasteur Institute of Iran and Sharif University of Technology. During the 12-day war between Israel and Iran in June 2025, Israel’s Weizmann Institute of Science and Ben Gurion University were also hit.

“Scientific and educational institutions are civilian spaces essential to public health, knowledge, and human survival,” the letter states. “Their destruction endangers researchers, students, medical personnel, and the broader public, while causing lasting harm to science and society.”

Qaiumzadeh says that many of the Iranian research institutions that have been destroyed were built over decades under sanctions. “My colleagues in Iran are deeply disheartened to see that what they achieved under such difficult conditions has been reduced to rubble,” he says.

Due to the ongoing war, which began on 28 February, many schools, universities and research centres – in which more than 60% of Iranian students in STEM subjects are women – are now closed, with courses forced online under limited internet access.

Particle physicist John Ellis from King’s College London, who is among those who signed the letter, says that he counts many Iranian, Gulf State and Israeli physicists among his colleagues and friends and says he has visited some of the institutions that have been attacked.

“I deplore any and all military attacks on universities, and indeed other educational institutions,” adds Ellis. “I can only hope that this open letter and the publicity it receives may help convince the belligerents to refrain from such attacks.”

The letter now calls on all parties in the war to “immediately” end attacks on civilian scientific and educational sites. “Science is not a military target,” the letter states. “Universities and laboratories must not become battlefields.”

It also calls on international bodies to “document [the] damage”, “protect affected scholars and students” and “support independent investigations into violations of international humanitarian law”.

Qaiumzadeh told Physics World that he finds it “particularly troubling” the scientific bodies, such as academies and international scientific organizations, have remained largely silent during the conflict.

“They must understand that undermining academic institutions will only worsen the situation for those who believe in gradual, constructive change within Iran’s complex society,” he says.

The post Researchers express ‘grave concern’ over attacks on Iranian institutions and science appeared first on Physics World.

The quantum revolution is no longer a distant dream. It is unfolding right now, promising to shake up computing, communication and security on a global scale. The race to harness these transformative technologies will not, however, be determined by who succeeds in manipulating qubits – but by who can secure the ideas that make this technology possible.

Intellectual property (IP) is the currency of innovation, and in the quantum era, it will determine whether breakthroughs become valuable assets or lost opportunities. Quantum physics has already made a huge contribution to global economic growth: just think of the billions of transistors in the smartphones that we carry around in our pockets.

But the “quantum 2.0” revolution, which will exploit phenomena such as superposition and entanglement, is set to bring us entirely new kinds of devices. In fact, quantum computers are already developing so fast that they will soon complement (even if they probably won’t entirely replace) the classical computers we all take for granted.

Given the huge potential, it’s hardly surprising that many countries around the world have national quantum research programmes. The UK, for example, recently announced unprecedented levels of grant funding in this area as it enters a second – and hugely ambitious – 10-year quantum initiative. Bringing together entrepreneurs and inventors from diverse fields to develop scalable qubit architectures and quantum-secure networks, the programme is well placed to deliver a strong return on the initial investment.

Another sign of the UK government’s commitment to quantum technology, despite well-publicized cuts to other areas of physics research funding, is the SpeQtre satellite. Launched late last year as a collaboration between the Science and Technology Facilities Council, RAL Space and Singapore’s SpeQtral, it will test how “encryption keys”, based on entangled particles, could lead to ultra-secure space-based communication.

IP assets are important, being essentially government-awarded prizes that encourage innovation

For too long, though, the UK has pioneered groundbreaking achievements, but failed to turn those accomplishments into economic benefits. That’s why IP assets are so important, being essentially government-awarded prizes that encourage innovation.

When it comes to patenting quantum technologies, however, companies in the UK and the rest of Europe are falling behind competitors in the US and China. There is still time to catch up. But we risk losing out – even in our own markets – if UK businesses fail to protect their quantum innovations.

Patent protection

Despite being so counter-intuitive, quantum technologies need to satisfy the same patentability requirements as any other type of invention. They must, in other words, be new, inventive, industrially applicable, not excluded from patent protection, clearly defined and sufficiently explained.

Patent laws around the world are these days largely harmonized, although there is some divergence in how different countries assess whether an invention should be excluded from patentability. In the UK and Europe, for example, there are ways to get around patent exclusions for innovation that relates to discoveries, scientific theories, mathematical methods, business methods and computer programs.

Patent law is continually developing as it catches up with emerging science, especially in areas such as quantum computing, artificial intelligence (AI) and smart technology. The UK Supreme Court, for example, recently handed down a judgement that brought UK law up-to-date regarding how the patentability of inventions is assessed, especially those related to AI software.

Quantum algorithms can be patented by demonstrating technical effects that have been achieved

When it comes to assessing patentability, quantum computing is held to the very same standards as classical computing. Quantum algorithms, for example, can be patented by demonstrating technical effects that have been achieved. What’s more, guidance provided by the UK Intellectual Property Office explains that aspects of superconducting and/or photonic circuits for controlling processing and measuring qubits would likely escape exclusion.

Developments in quantum theory can be protected too, although to obtain patent protection, the patent application will need to explain how those quantum effects could be implemented by bringing together hardware that is already available today. It is worthwhile as well for patent applications that cover quantum innovation to set out the commercial opportunities that are envisaged.

Audit your assets

But it’s not all about patents. If you are looking to launch a business in the quantum sector, there are some other IP rights that are worth bearing in mind too. Registered designs, for example, can protect the appearance of products that you have created. Semiconductor topography rights can protect the design of integrated circuits, while trade marks can protect your brand, so that your business stands out from the rest of the market.

Building a robust IP portfolio is paramount for persuading investors that they should take the opportunity to support the deployment of quantum solutions

An IP audit by a patent attorney will help to identify the variety of ways to commercialize your quantum innovation, while also highlighting the risks as well as the potential opportunities too. Building a robust IP portfolio is paramount for persuading investors that they should take the opportunity to support the deployment of quantum solutions.

Remember though, that if you intend to pursue patent protection, you’ll need to file your patent application before your innovation is revealed to anyone who is not obliged to keep it confidential. Before you publish quantum physics research, you should therefore seek advice from a patent attorney, to ensure that your IP strategy aligns with your commercial objectives.

As theoretical and experimental quantum science matures into commercial applications and government industrial strategies, physicists will continue to make a vital contribution in shaping how their discoveries are to benefit our society. Together we will build a successful quantum economy.

The post Why patents are so vital for the quantum economy appeared first on Physics World.

A fundamental theory in electrostatics is that two particles with the same charge will repel and two particles with opposite charge will attract. This idea is built into most models that describe how particles behave in liquids. Yet over the past several decades, experiments have revealed that like charged particles can attract each other in solution, forming clusters that standard theories cannot explain. 

In this work, researchers explore this unusual phenomenon and find that the attraction between like‑charged particles is strong, long‑ranged, and sensitive to the particles’ surface chemistry and size. Using optical imaging, they directly observed how pairs of charged microscopic spheres interact in different liquids with high precision. They tested particles with various surface coatings, including DNA and lipid bilayers, the same material that forms cell membranes. 

Conventional electrostatic models treat the solvent as a uniform medium with a single dielectric constant, but real solvents (such as water) have structure, form hydrogen bond networks, orient themselves around charged surfaces, and can exhibit long‑range correlations. This research suggests that the way water molecules organise around charged surfaces creates an additional attractive force, known as the electrosolvation force. DNA coated and lipid coated particles show especially long‑range attraction, indicating that the interaction depends not only on the solvent but also on the chemical and structural properties of the particle surface. 

Overall, this work shows that like charged particles can attract each other over unexpectedly long distances, something current theories say should not happen, revealing a missing piece in our understanding of electrostatic forces in liquids. These insights could reshape models of biological self-organisation and help explain how molecules such as DNA, RNA, and membranes naturally cluster and form structures inside cells. 

“We are really excited about this emerging discovery and the possibility that what has been uncovered so far on interactions in fluids may be just the tip of the iceberg…” – Professor Madhavi Krishnan, University of Oxford

Do you want to learn more about this topic?

Assembly of colloidal particles in solution by Kun Zhao and Thomas G Mason (2018)

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The Hall effect is a voltage that appears across a material when a current flows through it in the presence of an external magnetic field. The nonlinear Hall effect, however, can occur without a magnetic field if the material’s internal structure is asymmetric. It typically appears under an AC or oscillating electric field, and the resulting Hall voltage scales with the square of the input current, making it a nonlinear response. Researchers are interested in this effect because it could enable new types of sensors, low‑power logic elements, and electrically switchable quantum devices. But so far, the nonlinear Hall effect has been difficult to control in a reliable, switchable way. In this work, the scientists demonstrate a new method to control the second‑order nonlinear Hall effect using a gate electric field. They show that certain bilayer materials can switch the effect on and off when a gate field is applied, functioning much like a transistor. The switching is non-volatile, binary (ON/OFF), and does not require magnetism.

The researchers focus on bilayer SnSe and SnTe, well known ferroelectric and thermoelectric materials. Although these bilayers appear symmetric overall, each layer carries a hidden internal polarization. This hidden polarization is tied to a layer‑locked hidden Berry curvature dipole, the quantum property responsible for generating the nonlinear Hall effect. Under a gate field, the hidden polarization behaves like a pseudospin, and the gate field acts as a pseudospin Zeeman field, selecting the preferred orientation of this polarization. Reversing the direction of the gate field flips the pseudospin orientation and therefore switches the nonlinear Hall response.

By screening 80 possible bilayer symmetry groups, the authors identify 18 that can host this switchable effect, establishing a universal design principle for creating electrically switchable nonlinear Hall devices. This approach combines symmetry analysis, effective modelling, and first‑principles calculations, and it opens the door to future nonlinear quantum electronics. The same design principle can also be extended to other gate‑field-controllable nonlinear transport and optical phenomena, including the circular photogalvanic effect, the nonlinear Nernst effect, and second‑harmonic generation.

Do you want to learn more about this topic?

Recent advances in the spin Hall effect of light by Xiaohui Ling, Xinxing Zhou, Kun Huang, Yachao Liu, Cheng-Wei Qiu, Hailu Luo and Shuangchun Wen (2017)

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We’ve congregated outside the main physics lab at the University of Dschang in Cameroon when a shouting match ensues about the two red cards issued in last night’s football match. It’s as dark as night inside and the lecture on LAMMPS-GUI, a molecular dynamics modelling software, hasn’t started yet because it’s been raining. The power is out and the prof, who has access to the generator, has delayed his trip to work so as not to get wet.

These are typical scenes in central Africa, where learning is a challenge. There is no WiFi in the university so we have come armed with routers to get online. Students can’t use the university toilets due to lack of running water and researcher professors have to provide their own batteries for the much-needed generators that run the projectors and overhead lights.

I’m here to attend the seventh Central African School on Electronic Structure Methods and Applications, which is being held alongside one of 23 satellite events to the Global Physics Summit (GPS) in Denver, Colorado, US. Organized by the American Physical Society (APS), the GPS is the world’s biggest physics conference, with 14,000 delegates, but not everyone has the time, money or visa paperwork to attend in person.

That’s why it’s great that the APS, along with AIP Publishing and IOP Publishing – which together form the Purpose-led Publishing (PLP) coalition – are hosting satellite events across Africa, Asia, the Middle East and South America to expand participation in this year’s GPS.

I’ve made the journey on behalf of the PLP to hold an editorial school at the university, teaching a variety of topics from artificial intelligence publishing policies to how to review academic papers. In my session with senior-career researchers at the university, I’m swamped with questions every time I pause to take a breath. They range from philosophical queries about funding access in the region, to funny misunderstandings, including when my pronunciation of “ORCID” misaligns with theirs.

The conference has also attracted participants from neighbouring countries, including Stève-Jonathan Koyambo-Konzapa from Central African Republic, Gervi Moussavou Mouketo from Gabon, and Cladi Rodnet Boulingui who’s spent three days travelling by bus from Brazzaville in the Republic of Congo.

The University of Dschang is a highly regarded institution in central Africa, so for Boulingui, whose visit is  sponsored by the Universität Duisburg-Essen in Germany, it’s been worth it.“Dynamic simulations are highly relevant to my work, it’s worth the journey to access the specialist lecturer,” he tells me.

The organizing director, Stephane Kenmoe, has joined from Germany, where he is an associate professor at the faculty of chemistry at Duisburg-Essen. He regularly visits his alma mater, and current students benefit from connections he’s made around the world. He brings his entrepreneurial spirit with him: Kenmoe is an active promoter of the APS satellites in Africa, has made award-winning films about science, and is a champion of community engagement.

This collegiate spirit extends to the heads of department who have been called upon to write PhD curricula for neighbouring Francophone countries where scientific funding is lacking.

We end the week watching a film that Kenmoe has worked with the local film industry to produce, Seeds of Science. The film shines a light on the high percentage of child labour and child marriage in the region. The actress playing the young girl who is forced to marry instead of continue her studies has joined us from nearby Bafoussam to watch the showing.

Thankfully, Aisha is still studying, particularly enjoying economics, geography and English. There is a sombre mood in the room, only interrupted by laughter when the power fails. The power may be out but the joy and passion for learning continue to burn here in Dschang.

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Earlier this year a group of researchers led by Sören Arlt of the University of Tübingen set out to stretch the limits of how far artificial intelligence (AI) can contribute to scientific discovery. In work published in Nature Machine Intelligence, they developed a language model capable of generating classes of blueprints for quantum optics setups that produce specific families of quantum states. Their model was able to design several experimental configurations that successfully generated desired, and in some cases previously unknown, constructions within the limits of its training.

Beyond this immediate technical achievement, the implications of this approach are striking. In principle, a researcher could ask a system like this to propose experimental setups for a desired quantum state without spending months or years exploring possible configurations. Such capabilities could accelerate research in areas like quantum computing and quantum communication, where specially engineered quantum states serve as key resources. Although the system still has clear limitations – it cannot always guarantee that the produced state perfectly matches the target and it sometimes fails to find a solution – this study demonstrates that machine learning can already contribute meaningfully to scientific discovery, even in the design of physical experiments.

Earlier attempts had already hinted that AI could assist in designing quantum experiments. In 2016, researchers from Mario Krenn‘s group (in which Arlt is a doctoral student) demonstrated that automated search methods could propose previously unknown quantum optics experiments capable of generating complex entangled states. Since then the field has grown rapidly, with tools such as PyTheus producing candidate experimental designs and revealing physical mechanisms that researchers had not previously recognised.

This time, instead of searching directly for a single experimental setup, the researchers trained a transformer-based language model on a dataset linking target quantum states to experimental blueprints. Given a desired state, the model generates Python code describing how to build a corresponding experiment. Based on the same transformer architecture used in modern language models, the system translates a quantum state into a program that constructs it experimentally. This output can be interpreted directly by researchers, allowing them to run the proposed construction and understand the design rules that the model discovered.

Using this approach, the researchers constructed 20 classes of quantum states of interest, among them well-known entangled states, such as GHZ, W and Bell states, some of which had no known experimental construction rules. Out of these, the system generated valid construction rules for six classes: four corresponded to already known solutions, while two corresponded to genuinely new construction rules for generating particular classes of entangled quantum states.

Rather than discovering entirely new states, the system identified previously unknown ways of assembling optical components that produce states with the required entanglement structure. The team verified these constructions computationally by simulating the resulting quantum states and comparing their fidelity with the target states. Although the experiments have not yet been carried out in the laboratory, the proposed setups provide experimentally testable blueprints.

The practical implications of tools like this are already prompting debate. Some see them as accelerating scientific discovery by exploring vast experimental possibilities, while others raise concerns that increasing automation could sideline experimental intuition. The key advance over previous approaches lies in generalization: rather than producing a single design, the model generates a program capable of constructing experiments for an entire class of states. “Instead of designing a single experiment for one target, this approach generates a general program that produces valid experiments for a whole class of targets,” Arlt explains.

The researchers chose to explore states that are physically relevant across different areas of quantum physics, allowing them to probe entanglement patterns relevant to quantum simulation, communication and computation. In this sense, the system expands the experimental toolbox available to physicists.

In some cases, the system uncovered patterns that the researchers had not previously identified. “We discovered two construction rules that we did not know of before,” Arlt notes. In another case, it generated a different construction rule for a class of states that had already been solved, following a completely different experimental strategy.

Rather than replacing physicists, the authors see AI changing how experiments are conceived. Instead of manually assembling setups, researchers may define the space of possible configurations and allow algorithms to explore it. As Arlt describes it: “instead of thinking about how do I put these components together so my experiment works, we think about what should the space of possible configurations look like so my computer can explore it efficiently”.

Despite the use of machine learning, the system is relatively modest in scale, with roughly 100 million parameters. While this keeps the computational cost manageable, it also constrains the range of experimental sizes and resources that the model can handle. The model also does not verify the correctness of its own outputs, requiring explicit fidelity checks of the generated states.

Looking ahead, the team hopes to extend this approach to other domains of physics and combine it with additional discovery methods.

All in all, tools like this suggest a future in which computers assist not only with simulations, but also with proposing new experiments and uncovering patterns in physical systems. Rather than replacing physicists, such systems may increasingly act as collaborators, helping researchers explore experimental designs that would otherwise remain inaccessible.

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Researchers at Stockholm University in Sweden have found experimental evidence of a long-predicted critical point in water at -63 °C. The result, which they obtained by supercooling liquid water and probing it with ultrafast laser pulses before it could freeze, provides further evidence that liquid water exists in two distinct phases.

Water is a strange substance. Unlike most other materials, its liquid form is denser at ambient pressures than the ice it forms when it freezes. It also expands, rather than contracting, as it cools, and it becomes less viscous when compressed. All told, water exhibits around 60 different anomalous behaviours, and it is especially atypical when cooled below its usual freezing point. This so-called “supercooled” state of water occurs naturally in high-altitude clouds, and it can be produced in a laboratory by applying high pressures as the water is cooled to low temperatures.

In 1992, a computational study led by the physicist Francesco Sciortino (then at Boston University in the US) indicated a further unusual trait. According to simulations by Sciortino, Peter Poole, Ulrich Essmann and H Eugene Stanley, supercooled water can undergo a transition between two different liquid phases, with a liquid-liquid critical point (LLCP) occurring at pressures 2000 times higher than atmospheric pressure at sea level. “These two liquids would coexist on a line in the supercooled water’s phase diagram,” explains Stockholm’s Anders Nilsson, who led the new study. “As pressure is lowered and temperature is increased, the two phases would vanish to leave only one phase.”

At this critical point, where two phases meld into one, theory predicts that fluctuations will arise between the two liquid states. These fluctuations are not confined to the critical point, however. They also occur in a large region of the phase diagram at temperatures above it; indeed, the predicted phase diagram contains further anomalies that persist up to around 50°C. This means that the existence of an LLCP could play a role in the behaviour of water under ordinary conditions. In fact, its presence could provide a straightforward explanation for many of water’s oddities, especially at low temperatures.

Before the new study, though, this LLCP was only predicted, never proven. “It has been difficult to identify because it has not been possible to conduct experiments at the low temperatures at which ice forms very quickly,” Nilsson says.

A role for ultrafast lasers

The key to the latest work, which is detailed in Science, was a new technology. “Ultrafast X-ray lasers allow us to perform such experiments and probe water before it freezes,” Nilsson tells Physics World.

Working at POSTECH University and the PAL-XFEL facility in South Korea, Nilsson and his colleagues studied supercooled water using ultrafast infrared laser pulses followed by x-ray scattering. This allowed them to detect the phases formed before the supercooled water began to turn into ice. “By varying the laser’s fluence, we were able to access liquid states straddling the predicted critical point,” explains Nilsson.

The Stockholm researchers report that they observed a crossover from a discontinuous to a continuous transition, where the system undergoes broad and slow structural changes. Such a pattern agrees well with the existence of critical fluctuations at this point, Nilsson says. They also observed a rapid increase in the material’s heat capacity indicating a critical divergence at 210 ± 8 K, which is coincident with enhanced density fluctuations. “These results suggest that our experiments have directly probed the vicinity of a critical point in supercooled water,” Nilsson says.

Investigating the impossible

Nilsson adds that finding this critical point had long been a “holy grail” for scientists who study water, with many believing it would be impossible for experimentalists to access. As an X-ray scientist, however, Nilsson realized that the new generation of X-ray lasers could make a difference.

“I took on this challenge 15 years ago and the most difficult aspect was to move water through the phase diagram – by changing the pressure and temperature – very quickly and study it on ultrafast time scales (in less than a microsecond), before ice formation occurred,” he says. “It took us many years of planning and testing: we identified the two liquid phases, a result that we also published in Science in 2020, and have now finally succeeded in reaching the critical point.”

The researchers now plan to continue investigating the critical point in detail, with the goal of understanding the timescales of the fluctuations that occur as the pressure and temperature are nudged away from it. “We also need to research the implications of ordinary water becoming supercritical at interfaces that are important for energy applications, such as fuel cells and water splitting,” Nilsson says. “Other important areas to consider [include] how supercriticality is important for water in living cells; water as a solute for chemical reactions; water in geological pores; and water in clouds, which are important for understanding climate change.”

Team member Fivos Perakis adds that the results are “very exciting”, given that water is the only supercritical liquid known to be present under conditions where life exists. “We also know there is no life without water,” Perakis observes. “Is this a pure coincidence or is there some essential knowledge for us to gain in the future?”

• This article was amended on 27/04/2026 to clarify the roles of the scientists involved in the 1992 study that predicted a liquid-liquid critical point in water.

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Ian Griffiths studied physics at the University of Bristol in the UK, followed by a PhD in transmission electron microscopy (TEM). He remained at Bristol to do an EU-funded postdoc focusing on 3D gallium nitride LEDs, collaborating with academic and industrial partners in Germany, Spain and Poland. He also worked with the University of Oxford and the University of Southampton on an aberration-corrected scanning transmission electron microscope (STEM).

Following a brief period at the South West Nuclear Hub, Griffiths moved back to Oxford as a support scientist in the David Cockayne Centre for Electron Microscopy, where he managed and trained users on the high-end TEM, and supported electron microscopy research in the Department of Materials. In 2023 Griffiths joined microscope and spectrometer provider JEOL UK as a sales executive, supporting the electron microscope business across the south of England.

What skills do you use every day in your job?

Working in a sales role for a multinational company specializing in high-end microscopy equipment often involves collaborating with a wide range of users and customers. Communication and listening are key to ensuring the correct instrument is configured and offered to a customer.

Having been in academia specializing in physics and materials analysis, it’s easy to see electron microscopy as a technique for studying traditional metallic or semiconductor samples. In my current role, however, I interact with a whole spectrum of samples, from geological to future battery anodes to cryogenically cooled biological materials. It is important to be able to adapt my perception of the technology and also see the similarities between the techniques.

Above all, the main skill I use every day is to be approachable and understanding. The nature of the instruments I offer to customers means they are large value items that will form the basis of their work or research for years to come, and they have often put in a personal commitment to the project and are invested in finding the best solution to their problem.

What do you like best and least about your job?

The best aspect of my job is visiting a user to see their new instrument installed at their facility. It’s the culmination of a long process – from initial discussions, to visits and demonstrations, to ordering – and the excitement from the customer as they talk about future work they’ll be doing is great to see. Being part of their journey and helping them achieve it is a huge positive for me.

Another great part of my job is going to conferences and exhibitions to meet users and hear about the latest research. I’m lucky enough to sit on the organizing committee for the Royal Microscopical Society’s annual UK and Ireland electron microscopy meeting. The event aims to not only present the latest community updates, but also highlight the work of research technical professionals and facility staff in academia to give them greater recognition for the work they do in supporting students and researchers.

One of the parts I like least is discussing projects with users who are constrained with budgets and funding, and hearing about university departments that are sadly struggling for funds and being forced to reduce staff levels. Central facilities – both electron microscopy and other analytical techniques – are often key to the research output of a department but are also hard to maintain without effective central support.

What do you know today that you wish you knew when you were starting out in your career?

I wish I’d known earlier in my career that the most important aspect of a role is to enjoy it. If you find yourself no longer being challenged, look for something new to motivate you. I’ve enjoyed the different challenges and roles I’ve done since starting my physics degree, and while changing jobs is a daunting task, it has always been worthwhile.

On another note, I think I underestimated the role and progress that technology and AI would have in everyday aspects of our jobs. These will continue to change and progress, and it’s a good idea to be up to date on the latest innovations in your area.

The post Ask me anything: Ian Griffiths – ‘While changing jobs is a daunting task, it has always been worthwhile’ appeared first on Physics World.

While modern radiotherapy techniques provide high-precision cancer treatment, cure rates for some advanced cancers have plateaued, with five-year local control rates often remaining as low as 50–60%. Recently, researchers have hypothesized that this clinical resistance may be primarily driven by tumour heterogeneity.

Positron emission tomography (PET) is the gold standard imaging technique for non-invasively mapping biological processes in the body – and could help define tumour regions that may be more resistant to the effects of radiation. Yet conventional scanners remain “monochromatic”, limited to imaging a single radiotracer per session. This physical limitation means that radiotherapy plans are often based on a “one-size-fits-all” dose model that assumes uniform radioresistance across the entire tumour volume.

Multiplexed PET (mPET) is an emerging innovation that offers a significant enhancement by utilizing radiotracers that emit both positrons and gamma photons to detect multiple biological signals simultaneously. The technique holds promise for enabling biologically individualized radiotherapy, allowing for more personalized treatment plans tailored to the unique needs of each patient’s tumour.

Principles of PET

Positron emission tomography (PET) is a widely used functional imaging technique that enables the visualization of metabolic processes within the body. PET imaging relies on electron–positron annihilation, in which gamma-ray photons are emitted when a radiotracer (a pharmaceutical tagged with a positron-emitting isotope, most commonly ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG)) administered to the patient undergoes beta decay and emits a positron from its nucleus.

This energetic positron travels a short distance (typically less than 1 mm) through tissue until it encounters an electron in the body. Upon collision, the positron and electron annihilate, converting their mass into energy and releasing two 511 keV gamma photons, emitted approximately 180° apart to conserve momentum. These gamma photons are detected by scintillation crystals in the PET scanner, which convert the photon energy into light. This light is then captured by photomultiplier tubes (PMTs) or silicon avalanche photodiodes (Si-APDs) for precise photon event detection.

The fundamental detection mechanism in PET is coincidence detection, which relies on the arrival of the two photons at opposite sides of the detector ring within a very short time window (typically 6-12 ns). Each coincidence event defines a line-of-response (LOR), which connects the two specific points where the photons strike the detectors. By recording these coincidence events from multiple angles, the system reconstructs a detailed image of the radiotracer’s distribution within the body, allowing for the visualization of physiological processes.

Although PET provides excellent sensitivity for visualizing metabolic activity, conventional single-tracer PET is limited to only one biological process per scan. Since all positron-emitting isotopes produce identical 511 keV photons, standard scanners cannot differentiate between multiple radiotracers based on energy alone. This presents a significant challenge for modern clinical oncology, where tumours exhibit inherent heterogeneity. Different regions within a single tumour often have markedly distinct characteristics, such as variations in oxygenation and vascularization (the network of blood vessels developed by a tumour), which directly influence their radiosensitivity.

For example, hypoxic regions (which lack oxygen) within tumours can increase radiation resistance by up to threefold. While a single radiotracer like FDG can identify metabolically active regions, it does not capture hypoxic, radioresistant areas or variations in clonogenic cell density. This limitation forces radiotherapy to rely on a uniform approach, which often fails to address the complexities of tumour biology.

Sequential imaging with different radiotracers provides more insight into tumour biology but is clinically suboptimal, due to increased radiation burden from multiple accompanying CT scans (used for anatomical registration with the PET images) and higher costs. A method to simultaneously track multiple biological processes in a single scan is needed to fully capture the dynamic nature of tumour biology.

The physical principles of multiplexed PET

In standard PET scans, photons produced by positron–electron annihilation are detected when they arrive simultaneously at opposite sides of a detector ring, defining the LOR. Multiplexed PET builds upon these principles. With dual-tracer PET, however, the detection process becomes more complex due to the need to separate the photon signals from different radiotracers.

To achieve this separation, mPET exploits positron-gamma emitters such as ¹²⁴I, for instance, which in addition to emitting positrons, emit an additional prompt gamma photon following the positron decay. Such isotopes decay to an excited state of the daughter nucleus, followed by near-instantaneous emission of a de-excitation gamma photon. This additional photon enables the detection of triple coincidence events, providing more biological information in a single scan.

Using a triple-emitting radiotracer in combination with a pure positron emitter enables mPET scanners to achieve effective signal separation by utilizing an expanded energy window (350–700 keV, for example), which enables capture of both the 511 keV annihilation pairs and the higher-energy prompt gamma photons.

These data are then sorted into two streams: the primary dataset, which includes all detected LORs from both isotopes, and a smaller, tagged dataset containing only the triple coincidences. These triple events are identified via a specific timing selection rule, ensuring that the time difference between the prompt gamma detection and the average detection time of the annihilation photons falls within a narrow coincidence window, typically around 4.5 ns.

To reconstruct the separate radiotracer activity distributions, specialized image reconstruction strategies can be used to address the noise and artefacts inherent in basic subtraction methods. One approach is LOR sorting, which compares line integrals from the initial reconstruction to determine the likelihood that a specific LOR corresponds to one of the two isotopes. Furthermore, triple events can be reconstructed using V-shaped LORs, combining two probable LORs from a triple event into a single geometric unit to more accurately approximate the radioactive origin.

This process requires a spatially variant normalization factor that corrects for the camera’s varying efficiency in detecting prompt gammas across the field-of-view, as certain areas may be shadowed by the scanner geometry. Accurate reconstruction must also account for single-photon attenuation correction for the prompt gamma as it travels through the body.

By generating distinct datasets within a single scan, this method provides perfectly co-registered functional maps, allowing clinicians to simultaneously characterize multiple biological processes within a tumour in a single imaging session.

Towards personalized radiotherapy

The introduction of mPET facilitates the transition towards biologically individualized radiotherapy, by delivering perfectly co-registered functional maps in a single imaging session. One promising application is the treatment of head-and-neck squamous cell carcinoma, where the radiotracers ¹⁸F-FDG and ¹⁸F-FMISO have been used to map clonogenic cell density and hypoxia-related radioresistance, respectively.

Using radiobiological modelling, radiotracer uptake is converted into voxel-level cellularity maps via linear functions and oxygen partial pressure (pO₂) maps via nonlinear sigmoid functions. These biomarkers inform “dose-painting” strategies that strategically escalate radiation to radioresistant areas, such as the hypoxic target volume, while maintaining safe limits for adjacent organs-at-risk. Modelling indicates this synergistic approach could increase tumour control probability from the clinical standard of 60% to a projected 90% or higher.

Researchers have also validated the feasibility of mPET in melanoma mouse models. Here, mPET successfully separated the signals of the triple-emitter ¹²⁴I-trametinib (targeting proliferation) and ¹⁸F-FDG (targeting metabolism). This preclinical trial confirmed that mPET’s ability to separate dual isotopes offers a more detailed and timely assessment of tumour biology.

Future outlook

The clinical translation of mPET represents a significant potential advancement over traditional sequential PET scanning, providing an inherently quicker, cheaper and safer approach. By acquiring dual functional maps simultaneously, the second CT scan required in sequential procedures is no longer needed, roughly halving the patient’s cumulative radiation exposure.

Furthermore, mPET offers the advantage of shorter study duration, as both radiotracers are imaged simultaneously, eliminating the need to wait for the first to decay or wash out before injecting the second. This operational efficiency not only enhances patient compliance but also reduces total costs by minimizing scanner time and overheads. Crucially, mPET is highly viable for near-term implementation as it requires no modifications to existing hardware or acquisition software, when using standard clinical systems, such as the Siemens Biograph mCT, for example.

Despite these advantages, the primary technical pitfall remains the low statistics of the tagged “triples” dataset, which typically represents only a small fraction of total events. This statistical scarcity can introduce significant noise and “shadow” crosstalk artefacts into reconstructed images, potentially affecting quantitative accuracy. To mitigate this, ongoing research into bilateral guided filters and specialized V-shaped LOR algorithms is essential.

In addition, while the physics is compatible with current hardware, many clinical software packages still lack built-in capability for simultaneous multi-energy window acquisition or automated triple-coincidence tagging. This requires the development of manual workarounds that must be standardized for hospital use.

In the next five to 10 years, as the field moves from discovery into prospective interventional trials, the integration of machine learning for multi-parametric analysis will likely refine signal separation and tumour characterization. Looking further ahead, simultaneous imaging is not necessarily limited to two radiotracers: by utilizing multiple positron–gamma emitters and detecting their unique prompt gamma energies, mPET could evolve into “several-colour” imaging, capable or tracking three or more biological processes at once.

Ultimately, if upcoming trials confirm that predicted gains in tumour control probability translate into actual long-term patient survival, mPET may revolutionize oncology by enabling the first truly biologically individualized radiotherapy.

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The Dark Energy Spectroscopic Instrument (DESI) has created the largest high-resolution 3D map of the universe. The work involved observing more than 47 million galaxies and quasars as well as 20 million stars over a five-year period. Researchers will now use the vast dataset to probe the nature of dark energy.

DESI, which began collecting data in 2021, is mounted on the Nicholas U Mayall 4-m Telescope at the Kitt Peak National Observatory in Arizona. It comprises 5000 robot-controlled optical fibres that send light to an array of spectrographs.

This allows DESI to make an extensive map of galaxies and quasars with the spectroscopic data providing a measure of how fast a galaxy is moving away from us, which is determined by a galaxy’s redshift.

By comparing how galaxies clustered in the past with their distribution today, researchers can trace dark energy’s influence. Work published in 2024 found hints that the acceleration of the expansion of the universe has not been constant.

DESI will now use the expanded dataset to further test whether the “cosmological constant” could be evolving over time with the results expected to be published next year.

DESI director Michael Levi, who is based at the Lawrence Berkeley National Laboratory, says the survey has been “spectacularly successful and is “incredibly exciting”.

“The instrument performed better than anticipated,” he says, “We’re going to celebrate completion of the original survey and then get started on the work of churning through the data, because we’re all curious about what new surprises are waiting for us.”

DESI will now continue observations into 2028 and further expand the map by about 20% to include parts of the sky that are more challenging to observe.

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Quantitative trading plays an ever-increasing role in the global financial markets. Automated algorithms analyse millions of financial instruments simultaneously, while mathematical models anticipate price movements on nanosecond timescales.

Susquehanna is a proprietary trading firm, meaning it invests its own capital in the markets. Susquehanna’s quantitative researchers – or “quants” – collaborate with traders and technologists to drive the company’s success. Quants design and implement the complex models and algorithms the firm needs to make rapid, well-informed pricing and trading decisions.

The quant advantage

Lyubo Panchev, a quant at Susquehanna with seven years at the firm, describes how quants collaborate across a wide range of instruments and problem types. “Our quants are all trying to mathematically understand the world and the financial markets,” he says, “and then we use that information to determine whether we want to make a trade or not.” While the challenges vary considerably across the firm’s different trading desks, that shared mathematical mission is what unites them.

The details of this work can differ from quant to quant, from devising new pricing approaches for financial instruments, to finding patterns in data to turn into trading signals, to developing specialized software to implement new trading strategies.

However, specialist knowledge in specific fields is not what Susquehanna is primarily interested in when hiring a new quant. Instead, the firm is looking for the types of transferrable skills that PhD students in STEM fields often possess. “We want to hire people who can reason through first principles and feel comfortable working in an uncertain environment with open-ended questions to which answers sometimes might not even exist,” says Panchev. “So that’s why we like to hire PhDs.”

A physicist, for instance, brings the skills and intuition for modelling systems with incomplete information – whether that’s modelling interactions in a complex system or inferring signal from noise in a vast dataset. The mental frameworks used by a theorist studying quantum field theory or an experimentalist analysing data translate surprisingly well to pricing derivatives or spotting anomalies in market behaviour.

Life outside academia

Panchev – a three-time International Mathematical Olympiad medallist with a PhD in pure mathematics from MIT – says that the most satisfying part of working at Susquehanna for him is that it preserves what he loved about academia, while at the same time addressing some of the shortcomings.

“The freedom to work on what you want is a unique advantage in academia, over pretty much any industry,” says Panchev. “But what quant researchers do at Susquehanna is close to that spirit.”

Though he enjoyed focusing on challenging questions surrounded by like-minded people, he found working on hyper-specialized academic problems during his PhD a slow, lonely slog. At Susquehanna, quants work on challenging problems, but never in isolation. Quantitative trading problems are invariably interconnected, requiring close collaboration between researchers, traders, technologists and many other experts, to connect all the pieces together.

What’s more, the environment is highly dynamic. “The impact is much more immediate, sometimes instantaneous,” he adds. “You can be looking at the data and then decide to make a change to your algorithm, tweak a few things, and five minutes later, you’re already getting data that’s from the change you just made – it’s a very fast feedback loop.”

When you add a highly desirable salary, benefits package, career development opportunities, and a company culture that values strategy games like poker to hone decision-making skills and apply them to complex financial markets, it is clear to see why a STEM PhD student might choose Susquehanna over a career in academia.

From toy problems to market mastery

To earn a seat at this table, applicants are put through their paces. The first and perhaps greatest challenge they face is getting through the interview process. Quant skills – like original thinking, intuition, and problem-solving – are not easily described in a CV or interview, they need to be demonstrated. But how can an applicant demonstrate those skills in an interview?

“We build interesting toy problems that are representative of what we do,” explains Panchev. “And then we give them time to think and work on it on their own, before reconvening to see how they approached the problem, and what they found out.”

The internship builds solid foundations in finance domain knowledge, machine learning, programming and data analysis

Successful applicants who are hired on immediately participate in a comprehensive 10-week internship – the first step in an intensive front-loaded education program at the company. This internship builds solid foundations in finance domain knowledge, machine learning, programming, data analysis, as well as what Susquehanna’s different quant groups do and how their work all fits together.

Panchev says that a typical direct full-time hire requires five months or more of very structured education, over time, however, the quant will be faced with more open-ended problems and need to chart their own way, free to explore their own ideas and methods.

“There’s a long, steep learning curve but at the end you become an expert,” he adds. “In a way, it’s very similar to how a PhD is structured.” This means that, while the barrier to entry is fairly high, the support system is robust, with a well-organized education program that ensures that everyone is equipped with the tools that they need to succeed.

For the successful STEM PhD student assessing their career options, Susquehanna offers a compelling proposition – the chance to remain a scientist, but on a stage where the stakes are higher, the collaborations deeper and more dynamic, and the results play out in real-time and have real-world impact.

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A new highly stable and energy-efficient memristor based on a hafnium oxide material can emulate the behaviour of synapses in the brain. The neuromorphic device could help dramatically cut the energy consumed by artificial intelligence (AI) hardware, say its developers at the University of Cambridge in the UK.

Today’s AI systems rely on conventional digital computers. These have separate processing and storage units and consume huge amounts of energy when performing data-intensive tasks. As global AI use is exploding, this energy consumption has already become unsustainable, says materials scientist Babak Bakhit, who led this new study.

An alternative way to process information

Neuromorphic computers could provide an alternative way to process information. As their name suggests, they are inspired by the architecture of the human brain. The circuits in these computers are made up of highly connected artificial neurons and artificial synapses that simulate the brain’s structure and functions. These machines have combined processing and memory units that allow them to process information at the same time as they store it, in the same way as a multi-tasking human brain. This means they could reduce energy consumption by as much as 70% compared with their digital counterparts.

Memory-resistors, or memristors, have become a fundamental building block of such neuromorphic architectures. This is because they can be engineered to behave very much like neurons in the human brain, which learn by reconfiguring the strengths of the connections (synapses) between neurons. Memristors excel in this respect as they can bring this learning functionality to the connections in electronic circuits.

First described theoretically in 1971, it was not until 2008 that researchers made the first practical version of a memristor. These devices are special in that their resistance can be programmed and subsequently stored. This is because, unlike standard resistors, the resistance of a memristor changes depending on the current previously applied to it – hence the “memory” in its name. What is more, the device “remembers” this resistive state even when the power is switched off.

Randomness in switching behaviour is a problem

All well and good, but most of today’s memristors unfortunately suffer from randomness in their switching behaviour because they rely on the formation of tiny conductive filaments in the materials making them up. These filamentary devices also typically require high forming and operating voltages and extra devices to avoid uncontrolled current changes that lead to permanent device failure. These challenges make such devices difficult to scale up for real-world applications, says Bakhit.

The researchers, who report their work in Science Advances, claim to have overcome the intrinsic stochasticity of memristive switching by exploiting a completely different switching mechanism – based on carefully engineered heterointerface physics rather than random filament switching. They achieved this by adding strontium and titanium to a hafnium-oxide thin film, which results in the formation of a p-n heterointerface. This junction allows the device to change its resistance smoothly by shifting the height of an energy barrier at the bottom interface through the migration of electro-ionic charges, explains Bakhit.

The new interfacial device has an ultralow switching current of less than or equal to 10^-8 A, which is around 10⁶ times lower than those of conventional oxide-based memristors. It also produces hundreds of distinct and stable conductance levels that can be easily modulated, a key prerequisite for analogue “in-memory” computing. And that’s not all: the device can also undergo tens of thousands of switching cycles without losing its programmed states for around a day.

Looking ahead, the researchers say they will now be focusing on translating their material and device breakthrough into a functional computing system. “In particular, we are working on reducing the thin-film growth temperature (which currently stands at around 700 °C) so that it is compatible with standard semiconductor manufacturing (CMOS) tolerances,” says Bakhit. “We will then scale up device arrays to demonstrate large-scale integration.”

Ultimately, the goal is to move from individual devices to fully integrated neuromorphic chips that can compete with, or surpass, conventional AI hardware in both performance and energy efficiency, he tells Physics World.

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How did you get on?

10 words Warming up nicely

16 words Getting hot, hot, hot

22 words Top dog!

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Collisional quantum gates based on fermionic atoms have been realized independently by researchers in Germany and Switzerland. The gates are a long-proposed building block for quantum processors, but had been very challenging to create.

Both teams’ gates achieve entangling operations with a fidelity above the theoretical threshold for quantum error correction – and could potentially be particularly useful for simulations of quantum chemistry.

The potential of collisional quantum gates was proposed in the late 1990s by researchers such as Peter Zoller of the University of Innsbruck in Austria and Ivan Deutsch of the University of New Mexico in the US. The underlying principle is that the states of qubits are encoded into the spin states of atoms in an optical lattice. Then, gate operations between qubits are performed by manipulating interactions between the atoms’ wavefunctions. Experimental attempts followed shortly after, but the technology of the time was insufficient to create practical gates.

Early schemes

“Schemes were developed to move the atoms using state dependent potentials, but the laser light was too near resonant, so it worked in principle, but in practice there was too much heating involved,” explains Konrad Viebahn of ETH Zurich and a member of the Swiss team.

German-team member Petar Bojović of the Max Planck Institute for Quantum Optics in Garching adds that imaging the resulting gates was another problem: “They got some first collisional gates showing proof of principle that this could possibly be done at around the same time as they did [trapped] ions, but they couldn’t move further and scale this up or do many more things with it because there was no way to really see the individual qubits and individual gates”.

Since those early days, much progress has been made in quantum-computing schemes that use neutral atoms held in optical tweezer arrays. During a gate operation, one atom is laser excited to a high-energy, large-size Rydberg state in which its wavefunction easily overlaps with the other atoms – allowing atomic qubits to interact.

There are, however, challenges associated with this architecture. Rydberg states are loosely bound, so the qubits are prone to disruption by classical noise. Furthermore, ensembles of Rydberg atoms tend to be large and this is a barrier to scaling-up the architecture.

Robust collisional quantum gates

Bojović and colleagues at the Max Planck Institute led by Titus Franz and Viebahn’s group at ETH Zurich now unveil independent work on new, more robust collisional quantum gates using fermionic lithium-6 atoms. Lithium has the advantage of being lighter, which allows for faster gates.

Most prior work on collisional quantum gates has used bosonic atoms, explains Viebahn, but using fermions makes the gates more robust because the exclusion principle guards against gate errors: “For our [collisional] implementation, the wavefunctions are allowed to overlap completely, and this amplifies the effects of quantum statistics,” he says.

Both groups produced two-qubit gates, including those able to perform entangling operations, with fidelities of over 99%. The Max Planck researchers controlled the interactions between the qubits by manipulating the potential barriers between them. They utilized an optical lattice among the most stable in the world, together with a quantum gas microscope that allowed single-site resolution.

“There’s been some criticism from other communities,” says Bojović; “Once you get to a regime of ‘ninety-nine point something’ fidelity, you really need to be able to see it precisely in order to characterize it.” The researchers would like to go on to demonstrate all the other gates in a universal quantum gate set, but Bojović says that researchers in quantum chemistry are already intrigued by the potential of the platform to simulate molecular behaviour.

Different protocol

The ETH Zurich researchers used a different protocol involving control of the bias voltage to couple the quantum states of their fermionic atoms rather than manipulation of the barrier height. The researchers have not achieved single site resolution – they are currently working to do so – but Viebahn believes his group’s protocol should prove more robust to noise.

“I would say the key novelty here is that we came up with this more robust way of doing this interaction, which was not part of the original proposals from the 90s,” says Viebahn. “We’re the first to implement this gate where these qubits form this fully overlapped quantum state.”

Both groups’ two-qubit gate fidelities are well above the theoretical minimum required for quantum error correction (QEC) to be possible. However, implementing QEC will be difficult  because creating the required universal gate set involves a complete set of single qubit gates as well as at least one two-qubit gate that can generate entanglement in the system. Nevertheless, Viebahn concludes, “The two-qubit gate is limiting many other quantum computing platforms, and that’s the thing that we’re very good at.”

The collisional quantum gates are described in two papers in Nature: links to the Max Planck paper and the ETH Zurich paper.

Quantum-computing expert Barry Sanders of University of Calgary in Canada says the papers “have two different purposes and both purposes are significant”. The Max Planck paper, he says, is especially impressive because it opens up the potential to simulate the Fermi–Hubbard dynamics of strongly-correlated electronic systems directly in a quantum simulator. The ETH Zurich paper, meanwhile, uses Fermi dynamics to offer gate operation protection against time-dependent sources of error. “There’s a lot of rich physics available with two fermions at a site,” he says.

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We are pleased to announce a forthcoming webinar that presents the very latest developments concerning atomic-scale devices and quantum platforms, and following on from two roadmap publications in Nano Futures that map out the potential pathways of these technologies. The webinar will feature four speakers who will present the status of four distinct research disciplines together with the key challenges and methodologies by which these may be overcome as quantum platforms and single-atomic devices are translated to the level of scalable quantum technologies.

Meet the esteemed panel of experts:

Chair and moderator

Vincenzo Pecunia, Simon Fraser University, Canada
Vincenzo is an associate professor and the head of the Sustainable Optoelectronics Research Group at Simon Fraser University, Canada. His research focuses on printable semiconductors and their applications in photovoltaics and sensing. He earned his PhD in physics and conducted postdoctoral research at the Cavendish Laboratory, University of Cambridge, UK, from 2009 to 2016. Before that, he earned his BSc and MSc in electronic engineering at Politecnico di Milano, Italy. His research breakthroughs include pioneering lead-free-perovskite-based indoor photovoltaics, ultra-low-power printed-thin-film-transistor electronics, and advanced spectrally selective printable light sensors. In recognition of his contributions, Vincenzo has received many awards and honours, including the Fellowship of the Institute of Materials, Minerals & Mining (FIMMM), the Fellowship of the Institution of Engineering and Technology (FIET), and the Fellowship of the Institute of Physics (FInstP).

Speakers

Steven Schofield, University College London, UK
Steven studied physics in Australia at the University of Newcastle (BSc) and the University of New South Wales, Australia (PhD). Following his PhD, he was awarded an Australian Postdoctoral Fellowship, which launched his independent research career. In 2008, he moved to the UK and in 2009 was awarded a five-year EPSRC Career Acceleration Fellowship. He joined UCL as a lecturer in 2012 and has since progressed to professor of physics, with a joint appointment at the London Centre for Nanotechnology and the Department of Physics and Astronomy. His research focuses on understanding and controlling the quantum properties of materials at the atomic scale, combining scanning tunnelling microscopy, synchrotron-based experiments, and theoretical modelling, with a particular interest in how these properties can be harnessed for future electronic and quantum technologies.

Joris Keizer, University of New South Wales, Australia
Joris is a tenured associate professor at the School of Physics at the University of New South Wales, Sydney, Australia. Joris is widely respected as an expert in atomic-scale quantum device fabrication. He is currently the team lead for developing deterministic atomic-precise dopant placement and 3D fabrication techniques for error-correction at Silicon Quantum Computing (SQC). His work to date (six years in academia, seven years in industry) has focused on the fabrication of atomic-scale devices with the goal of realizing a surface code architecture in silicon.

Soo-hyon Phark, Center for Quantum Nanoscience, Institute for Basic Science, Republic of Korea
Soo-hyon is currently working as a PI at Center for Quantum Nanoscience (QNS) of Institute for Basic Science (IBS), where he is leading the research group “Atomic spin qubits on surfaces”. He got his PhD in solid-state physics from Seoul National University (SNU), South Korea, in 2006, for an experimental research on single molecule magnets on surface using scanning probes. He joined QNS in October 2016 and has been leading the project “Electron Spin Qubits on Surfaces” from 2019, using STM equipped with electron spin resonance. He has developed a novel qubit platform using atomic spins on a solid surface for the first time and demonstrated quantum-coherent manipulation of multi-qubit systems (2023). In recognition of these pioneering contributions to the quantum-coherent nanoscience field, he has been awarded the Minister’s Commendation for Outstanding Scientists of the Year 2024, The Best Award in Sciences and Infrastructures of the 100 National R&D Achievements, from Korean Ministry of Science and ICT in 2025, and The 1st ACS Nano Impact Awards from American Chemical Society in 2025. Currently, he continues and extends the projects using various atomic/molecular single spins towards quantum information science/technology using the bottom-up approach.

Franz Giessibl, University of Regensburg, Germany
Franz is the chair for Quantum Nanoscience at University of Regensburg in Germany. He obtained his diploma in physics after studies at the Technical University of Munich and ETH Zürich. He was the PhD student of Nobel laureate Prof. Gerd Binnig with the IBM Physics Group Munich at the Ludwig-Maximilians University, where he built the first atomic-force microscope (AFM) for ultrahigh vacuum and low temperatures. He continued his work on AFM at Park Scientific Instruments, a Stanford spinoff, where he established AFM as a surface science tool by obtaining for the first time the atomically resolved Si(111)-(7×7) reconstruction published in Science 267, 68 in 1995. During a two-year break from science, as a management consultant with McKinsey & Company, he invented the qPlus sensor, a new core for AFM, in his home laboratory and returned to academia. The qPlus sensor enabled transformative works in science since and Giessibl has been awarded 10 international science prizes for his work on AFM so far, including the Keithley award of APS, the Feynman Prize of Nanotechnology, the Heinrich Rohrer Grand Medal and the NIMS award of Japan.

About this journal

Nano Futures is a multidisciplinary, high-impact journal publishing fundamental and applied research at the forefront of nanoscience and technological innovation.

Editor-in-chief: Vincenzo Pecunia is an associate professor and the head of the Sustainable Optoelectronics Research Group at Simon Fraser University, Canada.

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Gleb Zilberstein is my guest in this episode of the Physics World Weekly podcast. A physicist by training, Zilberstein applies the principles of proteomics to the study of historical objects including Renaissance manuscripts.

He is also a director of Israel-based SpringStyle Tech Design, which has created a special film that lifts proteins from the surfaces of historical objects. Analysis of these proteins provides  important information about how those objects were used.

In a recent paper, Zilberstein and colleagues studied protein residues on a well-thumbed book of medical recipes that was published in Germany in 1531. He explains how their analysis provides a new view into how medical practitioners used the book and what sorts of concoctions they were making. Astonishingly, the team found evidence that European readers had access to ingredients derived from hippopotamuses.

Some papers about the application of proteomics to historical research:

• The Scientific Analysis of Renaissance Recipes
• Count Dracula Resurrected 
• EVA Technology and Proteomics: A Two-Pronged Attack on Cultural Heritage

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For radiotherapy centres, daily quality assurance (QA) provides the final safety check before each day of patient treatments – ensuring that all linear accelerators (linacs) deliver radiation safely, accurately and as expected.

But as radiotherapy technologies evolve, the required QA procedures become increasingly complex, with verification tests often performed in isolation using multiple phantom set-ups. New treatment techniques – such as surface-guided radiotherapy (SGRT), which is more widely used now than ever – also introduce new QA requirements. And the ongoing adoption of adaptive radiotherapy, where measurement-based pre-treatment QA is not possible, increases the emphasis on machine QA, in which daily QA plays a key role.

What’s needed is a comprehensive QA approach that incorporates the dosimetry, imaging and positioning checks required for all radiotherapy modalities. Addressing this challenge, US manufacturer Sun Nuclear has launched Daily QA 4 Pro, a new device that simplifies daily machine QA by combining dosimetry and positioning verification via imaging into a single indexed, imageable platform.

“The main motivation for launching the Daily QA 4 Pro was to create a product that not only met the current needs of clinicians, but also future needs, based on our vision of the radiotherapy QA field,” explains Rajiv Lotey, technical product manager for the Daily QA 4 Pro.

The next-generation platform builds on the company’s Daily QA 3 beam quality analysis product, which was introduced more than a decade ago and is now standard in many radiotherapy departments. “The biggest difference between the Daily QA 4 Pro over the Daily QA 3 is the end-to-end QA functionality – representing the patient workflow – achieved by integrating a 3D high-resolution array, fiducials, an SGRT-compatible surface, an imageable architecture, and the ability to correlate all imaging and mechanical isocentres together onto one device,” says Lotey.

Enabling new modalities, expanding clinical applications

David Barbee, Director of Technology and Innovation in Radiation Oncology at NYU Langone Health, was one of the first to adopt this technology. Speaking at the recent QA & Dosimetry Symposium (QADS) hosted by Sun Nuclear, he described his early experiences of using the next-generation Daily QA 4 Pro.

“The first thing I wanted to do was evaluate surface-guided radiation therapy, because we don’t currently do this during daily QA,” Barbee explained.

To perform this test, the team defined a region-of-interest in the hospital’s VisionRT SGRT system that covered the entire surface and edges of the Daily QA 4 Pro and tested it over the full range of couch motion. The maximum translation range that it could detect was about ±4.5 cm in the lateral (side to side) and longitudinal (along the couch length) directions, and +13 to –17 cm vertically.

“For pitch and roll, we tested the 3°/3 mm limits and 90° couch rotations, and it observed them perfectly,” he added. “This is the first time we’ve ever run this test and compared our SGRT system to our image guidance system,” he noted. “This is very, very helpful.”

For dosimetry, Barbee noted that many parameters are carried over from the Daily QA 3 – including the output profile constancy, the field size and shift, and the flatness and symmetry – but added that the Daily QA 4 Pro can measure at a much wider range, anywhere from 2 to 20 cm square fields. “There are also new metrics, such as the penumbra, beam shape constancy for FFF [flattening filter-free] fields, the beam centre and the dose-per-pulse,” he explained. “And there’s a new dose output correction factor for when you need to move this device to a different unit.”

Barbee and colleagues performed a range of dosimetry assessments using the Daily QA 4 Pro, measuring 30 sessions on six linacs using both jaw- and multi-leaf collimator (MLC)-defined field sizes. They found that the output factors were consistent down to about 7 mm, after which the MLC gave slightly higher output factors, while the largest beam profile differences were seen in flatness and symmetry for very small fields.

Integrating Winston–Lutz

The Daily QA 4 Pro incorporates active measurement Winston-Lutz tests – a standard procedure for evaluating isocentre accuracy – using the system’s onboard 3D detector array to directly measure the radiation isocentre. The NYU Langone team used the Daily QA 4 Pro to quantitatively assess the mechanical isocentres and their response to gantry, collimator and couch motion for six linacs, again using both jaw- and MLC-defined fields.

Barbee noted that the system runs the gantry and collimator checks automatically. “You can basically hit play on SunCHECK and then you don’t touch anything again until you get to the couch, which you have to move from the console,” he explained.

To test the accuracy of the results, Barbee compared them with two years’ worth of Machine Performance Check (MPC) and traditional Winston-Lutz measurements of all of the centre’s linacs. Daily QA 4 Pro measurements agreed well with previous isocentre results across all machines tested. “It’s a little bit early to say, but it looks commensurate, there are no concerns,” he noted.

A look inside the device

The Daily QA 4 Pro measures 30 x 50 x 6 cm, weighs 6.2 kg and sits on a 4.1 kg six degrees-of-freedom base. It incorporates four ion chambers that measure field sizes down to 5 x 5 cm, as well as 249 diodes spaced at high resolution in the x– and y-directions, the diagonals and along both sides. There are also eight 3 mm tungsten carbide BBs positioned off-axis, factory-calibrated to enable micron-level corrections.

Externally, the device incorporates scribed laser alignment marks with 2 mm tolerance on its sides and surfaces, plus a crosshair for collimator alignment. There are also field size markings for 5 x 5, 10 x 10 and 20 x 20 cm fields, as well as eight symmetric reliefs designed specifically for SGRT.

The Daily QA 4 software is designed to integrate into the SunCHECK environment and can be controlled using either SunCHECK Local via a standalone laptop or (starting in version 6.0) the SunCHECK Server.

The team also ran active imaging Winston-Lutz tests, which evaluate system geometry by analysing the position of a known target in images acquired using the linac’s imaging panels. The Daily QA 4 Pro device detects the image fiducials (tungsten carbide BBs) and compares their positions to expected values for each gantry angle. These tests allow users to assess factors such as device positioning, gantry angle accuracy and overall alignment.

“This is all summarized into a report showing the maximum error in any one of those parameters across all gantry angles,” explained Barbee. “It will tell you which gantry angle was the worst and what the value there was.”

Used together, the two Winston-Lutz methods combine direct radiation measurement with imaging-based verification to provide a more complete understanding of system health and to help identify, quantify and correct any errors.

Efficiency analysis

Barbee notes that while the Daily QA 4 Pro generates a comprehensive set of dosimetry and positioning verification data, at first glance, it looks like a lot more work. An efficiency analysis, however, proved the opposite – demonstrating significant gains in workflow efficiency.

Currently, Daily QA 3 and IGRT tasks take about 16 min to perform. “Daily QA 4 Pro cuts about five minutes off that time, because you’re not going in and out of the room and doing multiple setups,” he explained. “Adding Winston-Lutz currently doubles the time to over half an hour. But with Daily QA 4 Pro, you only add five minutes. And it’s a simple setup that your therapist can run as part of their morning QA.”

“The Daily QA 4 Pro integrates image-guided radiotherapy, SGRT, beam dosimetry and Winston-Lutz verification into a single device, enabling comprehensive daily QA in a single setup and session,” Barbee concluded. “This provides an independent, interpretable alternative to vendor black-box QA systems, with comparable isocentre and imager tests, and superior beam quality constancy tests. It really can consolidate a lot of phantoms that you might not need anymore.”

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India’s first prototype fast-breeder reactor (PFBR) has achieved criticality, marking a significant boost for the country’s nuclear programme. The 500 MW reactor, which is based at Kalpakkam, about 70 km south of Chennai, is intended to be a forerunner for a fleet of six similar fast-breeder reactors.

India’s currently has almost 9 GW of nuclear capacity from 24 plants, which are mainly pressurised heavy water reactors (PHWRs) that use domestic and imported natural uranium. Long-term, the Indian government wants to expand nuclear capacity to 100 GW by mid-century, quadrupling its share in electricity generation from 3% to 12%.

An Indian parliamentary panel examining the country’s nuclear programme warned earlier this year, however, that current capacity expansion is falling “significantly short” of the 100 GW target. The panel called for a “ring-fenced” funding mechanism and a clear roadmap and timelines to scale up fast-breeder reactors.

The PFBR uses uranium–plutonium mixed oxide (MOX) fuel and is designed to generate more fuel than it consumes. It does this by using a blanket of uranium-238 that surrounds the reactor’s core, absorbs neutrons and is transmuted into fissile plutonium-239. Work started on the PFBR in 2004 and it was originally supposed to open in 2010.

Despite delays and technical issues, the PFBR successfully achieved its first criticality on 6 April. “This is a historic moment,” says Anil Kakodkar, former secretary of India’s Department of Atomic Energy (DAE) who is now chancellor of the Homi Bhabha National Institute, told Physics World.

Three-stage solution

India has a three-stage nuclear strategy, in which PHWRs are the first stage, with the second involving spent fuel from PHWRs bring reprocessed into MOX fuel for fast breeders.

The third stage seeks to exploit India’s abundant thorium reserves – estimated at over a million tonnes of thorium compared to 433 000 tonnes of uranium – to produce uranium-233, potentially supporting energy demand for centuries.

Other countries, such as France, Japan and the US, have scaled back or deprioritised fast-breeder programmes due to technical and economic challenges.

Kakodkar cautions that the pace of future expansion will hinge on a shift from MOX to metallic fuel fast reactors, which use metal alloys and fast neutrons to breed new fuel. This could reduce the fuel doubling time in fast breeders from roughly 30 years to about a decade.

In parallel to the PFBR programme, the Bhabha Atomic Research Centre in Mumbai, has designed an Advanced Heavy Water Reactor (AHWR) to use thorium-based fuels. Kakodkar says that advancing the AHWR would “expedite transition” to the thorium fuel cycle by building institutional and industrial capability.

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A description of the evolution of metal-oxide-semiconductor device architectures and the corresponding requirements on epitaxial growth schemes will be followed by a discussion of the obtained material properties of Si/SiGe multilayer stacks used for logic and 3D DRAM devices, grown on 300 mm Si (001) wafers.

The process used to deposit Si/SiGe multilayers for Nano-Sheet devices has been extended to 120 pairs (241 sub-layers) of {65 nm Si/10 nm strained Si0.8Ge0.2} for 3D DRAM concepts [1]. A more complicated layer stack with two different Ge concentrations is required for the monolithic fabrication of complementary field effect transistor (CFET) devices, where gate-all-around nFETs and pFETs are stacked on top of each other [2]. A relatively high growth temperature provides acceptable Si and SiGe growth rates while still suppressing 3D island growth for SiGe growth with up to 40% Ge. Excellent structural and optical material properties of the epi stack will be reported, with up to 3 + 3 Si channels in the top and bottom part of the stack, respectively. For all layer designs, the absence/presence of lattice defects has been verified by several techniques including photoluminescence (PL) measurements at both room-temperature and low temperature.

[1] R. Loo et al., JAP 138, 055702 (2025), https://doi.org/10.1063/5.0260979

[2] R. Loo et al., ECS SST 14, 015003 (2025), https://iopscience.iop.org/article/10.1149/2162-8777/ada79f

Roger Loo joined imec in January 1997. Since October 2013 he has been a principal scientist (principal member of technical staff) in the group IV epi team. Since September 2023, he has also been a visiting professor (5%) at the Ghent University. He has authored or co-authored more than 240 articles in peer-reviewed journals. He has been co-editor of eight journal special issues, (co-)authored more than 250 articles in proceedings listed in Web of Science and has given more than 30 invited talks at international conferences.  Loo regularly gives invited research seminars and tutorials at universities, institutes and companies. Loo has co-authored more than 90 patent filings (including provisional filings), among which more than 50 patents have been granted and are maintained. He has also (co-)organized about 24 international conferences.

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Reservoir computing is a computational approach well suited to time‑dependent tasks such as speech recognition, because it relies on internal dynamics, nonlinear responses, and short‑term memory of recent inputs. However, most hardware implementations consume too much power and lack the rich dynamics needed for complex problems. In this study, the researchers introduce a new reservoir‑computing device made by connecting a ferroelectric capacitor (FC) in series with a linear capacitor (LC). This FC-LC device naturally provides the two essential ingredients of a reservoir: nonlinearity, through polarization switching and back‑switching in the ferroelectric layer, and fading memory, through slow charge accumulation and relaxation.

The device offers several advantages over existing reservoir hardware. It operates at extremely low power, produces a direct voltage output without extra circuitry, and has widely tuneable time constants, allowing it to respond quickly or slowly depending on the task. It also supports bidirectional operation, which increases the richness of its internal states and improves performance on classification tasks. By combining FC-LC devices with different time constants, the researchers create a hybrid reservoir with even greater computational capacity.

The system performs exceptionally well on a range of benchmarks, including heartbeat anomaly detection, waveform classification, multimodal digit recognition, and prediction of chaotic time‑series data. Because the device can be fabricated using established semiconductor processes and can be extended to widely used ferroelectric materials such as hafnium oxide, it is well positioned for large‑scale integration and future commercial reservoir‑computing hardware. This work lays the foundation for scalable, energy‑efficient reservoir systems that could enable fast, on‑chip processing in next‑generation electronics.

Do you want to learn more about this topic?

Many-body localization in the age of classical computing by Piotr Sierant, Maciej Lewenstein, Antonello Scardicchio, Lev Vidmar and Jakub Zakrzewski (2025)

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The concept of turbulence is one of physics’ most persistent challenges, defying a simple description despite decades of research. Adding quantum mechanics into the mix only makes things more complicated.

BECs are formed when atoms are cooled down to close to absolute zero. In this state they behave as a single coherent quantum fluid. They enable the observation of quantum behaviour on a macroscopic scale, enabling breakthroughs in fundamental physics and ultra‑precise technologies.

Waves can form within a BEC when it’s disturbed, just like in any other fluid. These can travel through the material, interacting, cascading and ultimately forming turbulent patterns.

When the turbulence is weak, and the chaotic interactions are small, perturbative wave‑interaction theories work well. A complete, simple theory of strong turbulence, however, remains elusive. Nonlinearities dominate and approximations break down.

The new paper sets out the conditions for a BEC to shift from weak to strong turbulence, offering a clearer way to interpret experiments and simulations. The work explains how nonlinear interactions, external driving, and dissipation help to shape the turbulent cascade. This process is analogous to classical turbulence but is fundamentally altered by quantum mechanics.

The authors emphasise that distinguishing the two turbulent regimes is essential for interpreting modern ultracold-atom experiments, where turbulence can be intentionally engineered using a shaking potential trap.

As BECs continue to serve as pristine platforms for simulating complex fluid behaviour, understanding their turbulent states is becoming increasingly important. The results of this paper will be invaluable for future investigations into quantum turbulence, non-equilibrium statistical physics, and the boundary where order gives way to chaos in quantum matter.

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The discovery of X-rays and radioactivity in the late 19th century gave rise to a surge of interest from the scientific community, shortly followed by the realization of the adverse effects of ionizing radiations on health. By about 1910 the dangers were widely recognised and some basic protection measures were being adopted. It was not until 1934, however, that the first quantitative standards of radiological protection were published.

Of course, protection against the adverse effects of ionizing radiation is as important today as ever, particularly for those working within nuclear and defence-related industries, medicine and R&D, as well as hospital patients undergoing radiation-based procedures and members of the general public. As such, the last century has seen the development of a complex international regulatory system, with recommendations on occupational and public exposures to radiation – from organizations such as the International Commission on Radiological Protection (ICRP) and others – continually revised and updated.

A new book, Principles and Techniques of Radiological Protection, provides a comprehensive overview of the current regulatory context for radiological protection. The text also provides an overview of the scientific issues relating to radiological protection and the current state-of-the-art tools used to comply with the relevant legislation and guidance.

Targeted at postgraduate students and new entrants to the field, the textbook is designed to cover a wide range of topics that an early-career radiation protection professional might need, or want, to know about. It also serves as a day-to-day reference work for specialists such as radiation protection advisors (RPAs) to identify appropriate techniques to address radiological protection issues as they arise.

“I aimed to produce a book that I would have liked to have had available when I started work in radiological protection just over 50 years ago,” explains the book’s editor Michael Thorne. “As I come towards the end of my career in the field, I aimed to include information, tools and techniques that I would have liked to have had readily accessible in a single volume.”

History, theory and practical applications

Thorne begins the book with a brief history of radiological protection and how historical developments continue to influence the discipline today. The next chapters examine the physical aspects of radiological protection, including an overview of basic nuclear physics and the sources of radiation, radiation transport through and interactions with matter, and the instruments used to detect and monitor radiation. Later chapters cover the principles of internal dosimetry, phantoms and biokinetic models, and mathematical modelling of radionuclide transport.

“I have also given a detailed account of natural background radiation and modelling the transport of radionuclides in the environment; and I have included a chapter on the effects of radiation on the environment, with specific emphasis on non-human biota,” says Thorne. “Throughout, I have recruited co-authors with decades of relevant experience to capture their expertise in each of the specialized areas.”

The book also provides examples of how this information is employed practically within various fields, including the nuclear industry and industries handling naturally occurring radioactive materials. Several chapters and themes are of particular relevance to those working within medical physics.

“There are two chapters specifically on radiology and nuclear medicine, written by Colin Martin, who is well known internationally for his work in this area,” Thorne tells Physics World. “There are also specialized chapters on biokinetic modelling, the nature and use of both mathematical and physical phantoms in radiation dosimetry, and on the use and abuse of instruments for radiation monitoring.”

The book rounds off with a look at the some of the major and minor accidents that led to exposure of members of the public and workers using radioactive sources. The final chapter addresses emergency planning and response for such incidents, including suggested protective actions and the roles and responsibilities of various organizations.

“Throughout, the emphasis is on broad principles and widely applicable techniques,” says Thorne. “It is considered that an individual who gains a clear understanding of these principles and techniques will be readily able to apply that understanding to the diverse and changing set of challenges that arise.”

• Individual copies of Principles and Techniques of Radiological Protection can be purchased at the IOP Publishing Bookstore.

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Black holes, as their name suggests, are veiled in darkness and mystery. These brooding celestial behemoths are regions of space–time that consume not just stellar dust and light but the attention of astronomers, artists and non-scientists too. Often depicted as shadowy maws ringed by fire, these inescapable pits intrigue us all.

“Science has produced a wealth of information about black holes that has been popularized worldwide,” says author, curator and art historian Lynn Gamwell. “This has prompted artists to delve deep into their creative imaginations to find the significance of black holes within a broad cultural context.”

Unable to escape from the lure of black holes herself, Gamwell – who teaches the history of art, science and mathematics at the School of Visual Arts in New York – has written and compiled Conjuring the Void: the Art of Black Holes. The stunning coffee-table book is a definitive – and near-exhaustive – collection of black-hole art, including 155 colour illustrations, perfectly mixed with information about the science and history of these objects.

Readers will undoubtedly fall into the pull of the book’s gravity, in which Gamwell skilfully weaves together our scientific understanding of black holes along with interpretations of these regions of space–time by artists around the world. Indeed, the book uses every medium available to decipher these objects.

With a background in the arts and humanities, Gamwell’s interest in science came while studying modern art. “The explanations of abstract, non-objective art that were taught to me never made sense,” she says. “While it seems so obvious now, I finally figured out that artists express their worldview and the modern worldview is shaped by science, which discovered invisible forces – such as electromagnetism – that can’t be pictured.”

Gamwell’s previous books – Mathematics and Art (2015) and Exploring the Invisible (2020) – both focused on the more abstract aspects of maths and science that are often complex and difficult to visualize. A few years ago, she was invited by physicist Peter Galison, director of Harvard University’s Black Hole Initiative (BHI), to give a talk at its annual conference.

“In researching for the talk, I was amazed to learn how many artists had done art about black holes,” Gamwell recalls. “So I decided to write a book about the artistic phenomenon and why black holes have captured the public imagination.” Gamwell is now an affiliate of the BHI, which brings together scientists, mathematicians and philosophers of science to deepen our understanding of black holes.

Given the interdisciplinary nature of her work, Gamwell regularly meets artists interested in science as well as scientists interested in art, including the Event Horizon Telescope’s Shep Doeleman, whom this book is dedicated to. “Artists and scientists arrive at similar ideas by different paths,” she says. “Both benefit from looking at each other’s work.”

The art – and, by extension, the artists depicted in Conjuring the Void – shows how the human conceit of “nothingness” links us to black holes. “On the one hand, the black hole provides artists with a symbol to express the devastations and anxieties of the modern world,” Gamwell writes. “On the other hand, a black hole’s extreme gravity is the source of stupendous energy, and artists such as Yambe Tam invite viewers to embrace darkness as a path to transformation, awe, and wonder.”

Below is an edited extract from chapter three of Conjuring the Void, illustrated by a selection of images of art from the book. They depict everything from colliding black holes and their gravitational waves to a black hole’s accretion disc and even a sonic wormhole. We hope they also take you on a journey of awe and wonder.

Artistic and scientific images of invisible objects

In the early 1970s the existence of black holes was reported in scientific papers and newspapers around the world, starting with the discovery of Cygnus X-1, introducing the phenomenon to the culture’s imagination. Scientists symbolized data in charts, graphs and mathematical formulae and attempted to make images of black holes. But seeing an object requires light, so rather than depicting a black hole itself, scientists imagined what matter surrounding it would look like. Artists, in turn, subjected scientific data to the transformation of the imaginative process and created something completely new: artworks.

Seeing an object requires light, so rather than depicting a black hole itself, scientists imagined what matter surrounding it would look like. Artists, in turn, subjected scientific data to the transformation of the imaginative process and created something new

Lynn Gamwell

In the decades before scientists showed that black holes exist, several artists in the West –including the American Barnett Newman, the Argentine-Italian Lucio Fontana, the American Lee Bontecou, and the Englishman John Latham – made abstract art about dark voids.

As scientists were confirming the existence of black holes, Frederick Eversley was imagining sculptures of them. He graduated in 1963 from the Carnegie Institute of Technology (now Carnegie Mellon University) in Pittsburgh with a degree in engineering and worked in the aerospace industry building acoustic laboratories for NASA. Around 1970 he transitioned to being an artist, creating abstract sculptures in cast polyester. With his background in science, Eversley understood the significance of the discovery of Cygnus X-1 in 1971.

That same year, the Brazilian artist Anna Maria Maiolino began a series of artworks about her life under Brazil’s military dictatorship. Whereas most artists in the early 1970s didn’t pay much attention to black holes because there were no visualizations of them to fire their imaginations, Maiolino became fascinated with holes filled with darkness.

Black holes were a metaphor for resistance to political repression in the work of Rudolf Sikora – in his case, from the Communist government of Czechoslovakia. In the early 1970s he began a series called Concentration of Energy featuring black holes.

Early scientific images of black holes

While Eversley, Maiolino and Sikora were in their studios making artworks about black holes, the US physicists C T Cunningham and James Bardeen were in their laboratory creating an illustration of the deformations in space–time around a black hole. They imagined a distant observer seeing a star orbiting a black hole at a uniform distance. They knew that the rapidly rotating black hole’s gravity affects light passing through its gravitational field in a manner similar to a powerful lens, hence the observer would see light that is distorted by what astronomers call gravitational lensing. Cunningham and Bardeen calculated these optical deformations and in 1973 produced the first scientific visualization of space–time around a black hole.

What would gravitational lensing do to the cloud of dust and gas that orbits a black hole called the accretion disc? The French astrophysicist Jean-Pierre Luminet wanted to make a realistic picture of an accretion disc. Associating realism with photography, he imagined the black hole “as seen by a distant observer” taking a “photograph” from a stationary, authoritative viewpoint. In Luminet’s diagram (see above), the accretion disc forms a flat, circular disc of dust and gas. Friction and magnetic forces heat the accretion disc to hundreds of billions of degrees until it becomes an incandescent plasma emitting radiation. The observer looks down on the disc from a slightly elevated position (at a 10-degree angle, labelled “observer’s direction”). While the accretion disc and stars emit light in all directions, for simplicity’s sake Luminet imagined parallel light rays coming from the observer’s direction.

Luminet made his drawing with tiny dots of black ink on white paper and then photographically reversed the image so that it reads white against a black background to create a “simulated photograph” of a luminous object in the darkness of space. His drawing shows one additional optical deformation lacking in Cunningham and Bardeen’s line drawing. The accretion disc displays a dramatic Doppler effect since it’s rotating close to the speed of light. Light appears closer to the blue or red end of the spectrum depending on whether the source is moving toward or away from the observer. In Luminet’s drawing, the disc’s left side appears to be moving toward the observer, so the observed frequency (hence the energy) of the electromagnetic waves is very high. Since Luminet’s image is black and white, he shows all radiation in the electromagnetic spectrum in what photographers call a bolometric photograph.

In Luminet’s image, the innermost stable circular orbit is the smallest circular orbit in which matter can stably orbit the black hole; it’s the inner edge of the accretion disc. If matter goes inside that orbit, it quickly falls past the black hole’s event horizon. Since light has no mass, it can orbit within the innermost stable circular orbit. If light crosses the event horizon it will not escape, but some photons circle on a narrow path between the innermost stable circular orbit and the event horizon. Scientists call this structure a photon ring (some call it a photon sphere because it’s three-dimensional).

Luminet published his work in 1979 and concluded with these prophetic words: “Thus our picture could represent many relatively weak sources, such as for instance the supermassive black hole whose existence in the nucleus of M87 has been suggested recently.” Forty years later, the black hole in the centre of galaxy M87 was imaged by the Event Horizon Telescope.

Added colour

Jean-Alain Marck – Luminet’s colleague at the Paris-Meudon Observatory – was an expert in general relativity, computer programming and calculating geodesics around a black hole. A geodesic is the shortest distance between two points on a curved plane. In 1989 Marck calculated the geodesics describing the accretion disc in Luminet’s drawing from various angles and, for dramatic effect, added colour. An image of a black hole from 1997 shows the far side of the accretion disc’s top side and underside. Marck and Luminet’s image had shown this view earlier, but it remained unpublished.

In the early 1990s Marck and Luminet collaborated on a sequence about black holes for a television documentary that was broadcast across Europe. Luminet had drawn his image by hand in the late 1970s because computer graphics programs were not available, but by the 1990s the technology had advanced and Marck was able to write the animation program himself. Marck’s calculation is unusual because it shows what a moving observer – riding a magic carpet and wearing a bow in her hair – would see flying past a Schwarzschild black hole on an elliptical trajectory.

While Luminet’s monochrome picture depicted the total radiation in all wavelengths, astronomers Jun Fukue and Takushi Yokoyama imagined a visible-light photograph of an accretion disc. Luminet, Fukue and Yokoyama visualized thin accretion discs around Schwarzschild (stationary) black holes and a thick accretion disc around a Kerr (rotating) black hole from an almost edge-on viewpoint. Artist Fabian Oefner created an artwork that is a metaphor for a multicoloured accretion disc, representing the visible light from a rotating black hole (see artwork at the top of this article).

If a black hole is rotating, the speed at which it spins affects the diameter of the innermost stable circular orbit; the faster it spins, the smaller its diameter. If a Kerr black hole spins extremely fast, it will distort space–time at the inner edge of the accretion disc. A thin accretion disc around a maximally rotating Kerr black hole from an elevated viewpoint shows asymmetry of the disc’s inner edge as the result of frame-dragging; the rotating black hole “drags” space–time along.

Melissa Walter created a sculpture that is a metaphor for gravitational lensing. Light passes through cut paper that sways and curves, distorting the light like a gravitational lens. Walter, unlike many artists, understands the crucial distinction between a science illustration and an artwork. Under her maiden name, Melissa Weiss, she works for NASA, executing science illustrations of how a black hole might actually appear, such as the widely used image of Cygnus X-1 and its companion star. Under her married name, Melissa Walter, she creates artworks. Speaking about the development of her oeuvre, she said: “Abstraction has been the common thread throughout that evolution as it relates to humanity’s place in the cosmos.”

Eric Heller is a physicist who studies wave phenomena in quantum mechanics, acoustics and oceanography. He’s also a practising artist who creates digital images about scientific subjects. In Black Holes Merging he imagined the pattern two black holes might make when they spiral into each other (see above left).

The popularization of black holes

In the late 1970s popular-science books about black holes began appearing, including Isaac Asimov’s The Collapsing Universe: the Story of Black Holes (1977). Having earned a PhD in chemistry, Asimov drew on a deep knowledge of science and was a skilled storyteller. Another title that contributed to the popular fascination with black holes was Stephen Hawking’s A Brief History of Time: From the Big Bang to Black Holes (1988) and the 1991 film based on it. Inspired by the words of Hawking, the Italian art collective Opiemme painted letterforms surrounding a long shape that symbolizes an event horizon.

Carl Sagan’s book Cosmos (1980) sold five million copies internationally. The related TV series, Cosmos: a Personal Voyage (1980), was hosted by Sagan and shown in 60 countries to 400 million viewers. A sequel, Cosmos: a Space–time Odyssey (2014), hosted by Neil deGrasse Tyson, was shown in 125 countries to 135 million viewers. Sagan and Tyson described many scientific topics, including black holes, which were brought to life by animators.

The impact of these popularizations was felt around the world, and artists in Asia mixed Western science with Eastern philosophy and history. Cai Guo-Qiang was in his 20s when he began experimenting with gunpowder as an artistic medium. When you explode a small amount of gunpowder on paper, it leaves a mark. Cai called these works “gunpowder drawings”. In 1986, at age 29, he moved from his native China to Japan and became enthralled by popular books about astrophysics, especially A Brief History of Time and Cosmos, which he read in translation.

Cai said: “When I came to Japan, my encounters with the theories of 20th-century astrophysics were very significant to me. The concepts of the Big Bang, black holes, the birth of stars, what is beyond the universe, time tunnels, how to leap over great distances of time and space and dialogue with something infinitely far away – these ideas were still not commonly in circulation in China at the time. They were an eye-opener for me. At the same time, many of these ideas have similarities with traditional Chinese views, with which I was familiar, of metaphysics and the universe.”

In 1991 Cai created large gunpowder drawings on paper mounted on wood panels, such as The Vague Border at the Edge of Time/Space Project. Then he joined the wooden panels together, transforming them into traditional Chinese folding screens. He called the series Primeval Fireball: the Project for Projects because his drawings, like the cosmos, exploded into existence.

Lucas J Rougeux was inspired when in 2014 astronomers watched as what appeared to be a cloud of dust (G2) approached Sagittarius A*. They expected the space cloud to be sucked into the black hole, but it survived the encounter. (Astronomers now believe that G2 was a binary star system that orbited the black hole in tandem, eventually merging into an extremely large star.) After learning about G2, Rougeux created a series of artworks about black holes (see above) that were shown in a 2022 exhibition titled The Soul Gravity—Guided to Black. The artist said, “The delicacy and amorphous nature of a space cloud is directly connected to my own sense of queer identity…I am a cloud of space dust. I am a collection of particles dealing with depression. I am weaving through waves of space–time and isolation. My work is the product of this existentialism, loneliness and search for a connection to the sublime.”

In 2022 NASA released a new sonification of the black hole at the centre of the Perseus galaxy cluster, which inspired the photographer John White. He painted the bottom of a petri dish black, filled it with water, and set it on top of a speaker. As he played the sound of the black hole through the speaker, the water began to vibrate. Shooting directly down at the petri dish with a macro lens and a halo light in a darkened room, he captured the vibration in a photograph titled Black Echo (see above).

Immersive art about black holes

Artists create immersive art – artworks the viewer can walk into – to enhance the immediacy of the experience. In 2016 the choreographer Wen-chi Su was an artist-in-residence at CERN, where she met the theoretical physicist Diego Blas, and they discussed the meaning of gravity in dance and astronomy. Su imagined what happens when a body falls into a black hole. Together with her production team, she directed a film in which the sets were animations and the movements of the dancer were captured by motion sensors. Additionally, a surround-sound system immersed the audience in a three-dimensional sound field.

Cao Yuxi (James Cao) is a computer artist who created an artwork about a black hole that he titled Oriens (Latin for “Orient”), giving it the subtitle Immersive Black Hole because the viewer is able to walk around in the space of the artwork (see above). His projection of a sphere on the wall suggests a black hole. A circle symbolizing the event horizon is projected on the floor, and flashing, curving lights communicate distortions in space–time near the black hole.

The American artist Yambe Tam, who merges Western science with Chinese philosophy, has said: “Black holes are a reoccurring theme in my practice. Beyond my interest in theoretical physics, I see connections to the Buddhist philosophical concept of the void/emptiness/nothingness, which is shared more widely with other Eastern spiritual traditions. Rather than signifying a negative space or absence of something, void/emptiness/nothingness is a space of infinite potentiality. It is during the practice of zazen [silent meditation] that I most feel an embodied sense of this – the emptying of oneself, or dissolution of form and ego into pure being.”

Tam’s Cosmic Garden was created to resemble a Buddhist dry garden. From the ceiling hang several of the artist’s sculptures that take the form of bells. One of these sculptures, Wormhole Bell (see above left) has feedback microphones that turn the object into a self-resonating instrument, which helps induce a deep state of meditation. In astronomy, a wormhole is a hypothetical tunnel that connects separate regions of space–time. Tam says: “To me, black holes and the speculative, double-ended form of the wormhole are symbols of transformation – whether the breakdown of classical Newtonian physics to general relativity or the spiritual transcendence one feels in contemplative practices like zazen. Physically, travelling into a black hole is obliteration – a return to pure atomic matter. However, in more philosophical and spiritual terms, a wormhole is an unknowable space of no return, a portal to another side of reality.”

• This is an edited excerpt from Lynn Gamwell’s book Conjuring the Void: the Art of Black Holes (2025 MIT Press 208pp £41 hb). Reproduced with permission, copyright MIT Press. All rights reserved

The post Lure of the black hole: from science to art appeared first on Physics World.

A major research institution in Russia is “deeply embedded” in the Russian military and the country’s military-industrial complex. That is the claim of a report by particle physicist Tetiana Berger-Hrynova, who argues that the activities of scientists belonging to the Joint Institute for Nuclear Research (JINR) in international collaborations should be limited as it poses a security threat to Europe (arXiv:2603.21896).

The JINR is an international research centre for nuclear science with 5500 staff members and prior to 2022 over 1000 scientists from JINR-collaborating organizations visited Dubna each year.

Berger-Hrynova, who is based at the CNRS’s Annecy Particle Physics Laboratory in France, told Physics World that her research was triggered by an article in December 2022 in the New York Times, which found that Kh-101 missiles – a Russian air-launched cruise missile – were produced in Dubna.

“I found that JINR scientists have played a critical role in developing Dubna into a major centre for Russia’s military-industrial complex — through dual-use research, knowledge-transfer programmes and personnel training,” says Berger-Hrynova.

According to Berger-Hrynova, who was born in Ukraine and educated at Liverpool University before doing a PhD at Stanford University, the lack of awareness of the issue has enabled scientists from Dubna to maintain their participation in international collaborations.

“JINR personnel can travel freely to scientific institutions in the EU and the UK, retain access to advanced technologies that can then be transferred to military and security actors through Dubna’s tightly connected research-industrial ecosystem,” claims Berger-Hrynova.

In 2022, following Russia’s invasion of Ukraine, CERN suspended JINR’s observer status at the lab, although Berger-Hrynova points out that the cooperation never stopped as in 2024 CERN’s council decided to maintain its international cooperation agreement with JINR for five more years, which currently allows 321 JINR scientists to be associated with CERN.

Indeed, JINR is also participating in the Russian Regional Center for Processing Experimental Data from the Large Hadron Collider (LHC) — a critical component of the Worldwide LHC Computing Grid.

JINR also still maintains links with nearly 700 research centres and universities in 60 countries and provides scholarships to physicists from developing countries.

The JINR is in addition actively involved in international and national scientific conferences, hosting up to 10 major conferences, over 30 international meetings as well as international schools for young scientists. Scientists from France, Italy, Germany, Latvia and other EU countries are also still on the JINR governing committees.

Ukraine applied sanctions against JINR in August 2025 given its alleged connections to military research and Berger-Hrynova now calls on other countries to do likewise.

“The JINR case illustrates how Russian scientific research institutions are used to circumvent sanctions, underscoring the need for coordinated enforcement among Ukraine, the EU, and the G7, as well as greater awareness within the international scientific community,” writes Berger-Hrynova.

Evgeniy Bragin, an official spokesperson for JINR told Physics World that “nobody from the administration of the Institute can provide comment”.

The post Joint Institute for Nuclear Research ‘deeply embedded’ in Russia’s military efforts, states report appeared first on Physics World.

When Werner Heisenberg retreated at daybreak to an isolated rock on the island of Helgoland in June 1925 to contemplate his development of quantum physics, he might well have been surprised to know that this moment would be recreated by an actor perched on the back of a chair in a pool of water on a stage over 100 years later.

However, this is exactly what happens in a revival of Michael Frayn’s play Copenhagen, currently at Hampstead Theatre in London.

The play explores Heisenberg’s visit to see Niels Bohr in Nazi-occupied Copenhagen in 1941 and features just three characters, Heisenberg, Bohr and Bohr’s wife Margrethe. The intentions surrounding Heisenberg’s visit have always been unclear, with this uncertainty being central to the play, which was first staged to critical and popular acclaim at the National Theatre, London, in 1998.

The initial success of Copenhagen came even as a surprise to its writer Michael Frayn. “When I wrote it, I didn’t think it would even be staged,” he admitted in an interview with Physics World. Eventually, Copenhagen went on to receive many accolades, including a Tony Award for Best Play and enjoyed over 300 performances in London and New York.

The new production at the Hampstead Theatre is directed by Michael Longhurst, who told me how struck he was by the level of detail in the play.

“While Frayn is super conscious of this as an act of fiction and theoretical imaging, I don’t think I’ve ever worked on a play that feels like it’s been as rigorously researched,” he says.

“I think there’s a real pleasure and opportunity as a director, when you’re staging plays that are tapping into scientific principles. There is a beautiful probing parallel between the uncertainty of intention and Heisenberg’s uncertainty principle.”

Heisenberg’s involvement in what became the German nuclear-bomb programme is likely to have been a significant factor in his seeking to meet with Bohr, but the beauty of the play is the uncertainty behind the real motivation for the meeting.

As Frayn told Physics World: “The play is about the elusiveness of human intention, so I don’t claim to have a settled view of Heisenberg’s.”

However, Frayn hints that he is most persuaded by Heisenberg’s own account, which he gave many years later, that he wanted to warn the Allies about Germany’s plan to build a bomb, rather than trying to get information from Bohr to help the Nazi programme.

“Bohr’s confirmation in his unsent letter [in 1957],” says Frayn, “that Heisenberg had in fact overridden all normal obligations of wartime secrecy to tell him that Germany was doing research on a nuclear weapon – and that he now believed it was in theory possible to build one – seems to me to go some way to reinforcing the account that Heisenberg himself gave later of his intentions in seeking the meeting in 1941.”

As for the new revival at Hampstead, Longhurst says it is a chance “to engage with an incredible play that hasn’t been seen in London since that original production”.

“I’m very proud of the cast that we’ve assembled in Damien Molony, Richard Schiff and Alex Kingston, who I think are individually and collectively brilliant. I guess what is thrilling about the play when you see it live, and it is three bodies in a contained space, is watching them shift between prosecutor, witness and judge. That triangle of relationships is constantly shifting. I like to imagine them as three entangled souls with an unanswered question.”

• Copenhagen runs at Hampstead Theatre, London, UK until 2 May.

The post Michael Frayn on <em>Copenhagen</em>: ‘When I wrote it, I didn’t think it would even be staged’ appeared first on Physics World.

Concepts from gauge theory could lead to a more efficient way to perform fault-tolerant quantum computation by reducing the number of qubits required for key operations – according to work done by Dominic Williamson and Theodore Yoder at IBM Quantum in the US.

By adapting ideas from gauge theory, the researchers show how quantum information spread-out across a machine can be measured using only local checks, significantly lowering computing overhead. Their approach works for a wide class of quantum error-correction codes and could help accelerate the development of practical quantum computers.

One importance difference between quantum computers and ordinary computers is how information is stored. Instead of bits, which can be either 0 or 1, quantum computers use qubits, which can exist in a combination of both states at once. Qubits can also be entangled and it is these and other quantum effects that can be harnessed to solve some problems much fast than conventional computers.

However, this power comes with a major drawback. Qubits are extremely sensitive to disturbances from their environment, which can easily introduce errors. This fragility is one of the main reasons why building large-scale quantum computers is so difficult.

To overcome this, researchers are developing fault-tolerant strategies that allow a quantum computer to continue working correctly even when some of its components fail. Williamson, who is now at Australia’s University of Sydney, describes this as using “carefully designed methods with built-in checks so that, when those checks pass, the final result has not been corrupted”.

Such methods typically store information held in one “logical qubit” across many “physical qubits” so that errors can be detected and corrected. But this protection comes at a cost, often requiring a large numbers qubits to perform even simple operations.

Measuring quantum information

In their new work, Williamson and Yoder tackle one of the central challenges in fault-tolerant quantum computing: how to measure information that is spread across many qubits without introducing too many extra resources.

The researchers draw on gauge theory, a concept from mathematical physics. “Gauge theories describe how local interactions can connect distant parts of a system,” Williamson explains. “In our work, we use this idea to measure information that is spread out across many qubits by adding extra helper qubits and performing only local checks.”

In practice, this means breaking down a complicated, global measurement into many small, local ones. By combining the outcomes of these local checks, the overall result can be reconstructed. This avoids the need for large, complex operations that would otherwise require many additional qubits.

According to the study, the number of extra qubits required grows only slightly faster than the size of the measurement itself. This is a substantial improvement over earlier methods, where the overhead could increase much more rapidly.

The approach is also flexible and can be applied to a wide range of quantum error-correcting codes. Barbara Terhal at the Technical University of Delft in the Netherlands highlights this point, noting that “the advance in this [work] is that it shows how to do this measurement in a reliable way for any of these codes, and also makes clear how many extra qubits are needed.”

She adds that such measurements are essential because they enable the key steps of quantum computation. “By measuring these operators, you can perform all the key steps needed for a full quantum computation.”

The method is particularly effective when implemented on highly connected structures that allow information to spread efficiently. Williamson notes that, “using this kind of highly connected structure reduces the number of extra qubits needed for fault-tolerant computation.”

Future directions

Despite its advantages, the new method does not remove all obstacles. One important trade-off involves time. Reducing the number of qubits can make computations take longer.

Terhal explains, “There is an inevitable extra time cost when you try to reduce the number of qubits”. In some cases, a system with fewer qubits may need more time to complete a calculation, while one with more qubits could run faster. Finding the right balance remains an open problem.

Another limitation is that the current study is largely theoretical. As Terhal points out, “[This work] focuses on the mathematical side and does not yet study how well the method performs in realistic simulations, which are very important for practice”. Further work will be needed to understand how the approach performs in real devices.

Williamson says, “We are working on ways to reduce the cost even more,” including lowering both the number of qubits required and the time needed to perform computations. He also notes that the method “has already been used in several follow-up studies” and is expected to appear in early fault-tolerant quantum computers in the coming years.

As quantum computing continues to advance, reducing the resources required for error correction will be crucial. By showing how to perform key operations with fewer qubits, the new work offers a promising step toward scalable and practical quantum machines.

The research is described in Nature Physics.

The post Gauge theory could give quantum error correction a boost appeared first on Physics World.

Humans perceive knowledge, make decisions and build the consciousness of knowing through vision and speech. This interplay between visual and nonvisual patterns collectively shapes how we learn complex concepts such as quantum physics. That is despite the subject’s reputation as being incomprehensible and difficult to reconcile with our everyday conceptions.

The issue when teaching quantum mechanics also lies in the shortcoming of using literary constructs to accurately describe what quantum mechanics really means. As the Hungarian-British philosopher Michael Polanyi once noted: “We always know more than we can tell.” It is hard to accurately capture in language the full meaning of quantum phenomena such as nonlocality, superposition, no-cloning, teleportation, counterfactual quantum computation, delayed choice or the many other uniquely quantum phenomena.

This also means that terms such as wave, particle, superposition and entanglement are not truly complete until followed by detailed calculations or elaboration of their consequences. The result is that introductory quantum mechanics courses often require prerequisite mathematical grounding in complex numbers, matrices, linear algebra and differential equations.

Yet I believe this tortuous preparation can be bypassed – in an accurate, comprehensive and consistent way – simply through “pictures”. With that in mind, we conducted an experiment last year at Government College University in Lahore, Pakistan – alma mater of the physics Nobel laureate Abdus Salam. The four-week-long summer school – Quantum in Pictures – was organized by the Khwarizmi Science Society, a not-for-profit grassroots science association that aims to make scientific education accessible especially for resource-deprived communities.

Some 50 school students attended lectures and demonstrations led by Muhammad Hamza Waseem from the UK firm Quantinuum, who works with Bob Coecke, one of the founders of a pictorial approach towards quantum physics and education.

Most of the students, who had no prior knowledge of quantum mechanics, came from Lahore while the remainder were from nearby towns and villages where opportunities especially in advanced fields are generally minimal. On top of that classroom engagement is largely discouraged and an outdated model of examination fosters rote learning. Almost half of the participants who attended the school were girls, with 75% of participants aged between 14 and 18 – the youngest being a 13-year-old girl from a village called Syedanwala in Kasur.

To capture ideas about quantum mechanics, we used “string diagrams” as our basis. Such diagrams, simply put, are made using boxes that represent processes. Wires coming in at the top and at the bottom represent the input and output systems being processed by the box. Simulating quantum processes translates to connecting boxes with wires, chopping and straightening wires or sliding boxes along wires like beads on a string.

Even though this formalism is rigorous and derived from category theory, the manner in which it is presented is unhindered by burdensome abstractions. In terms of quantum mechanics, such diagrams are able to capture ideas about how quantum states transform, how quantum operations work as well as counterintuitive notions about measurement.

A new confidence

When I teach quantum mechanics to undergraduates, colleagues often discourage me from “spilling the beans” on quantum mechanics too early before we have covered the mathematical acrobatics of Hilbert spaces, unitary transforms, eigenvalues and Dirac’s bra-ket notation. Yet I believe school students should relish the counterintuitive repercussions of quantum mechanics much earlier than they currently do. I believe that introducing such aesthetic visuals – an overlooked concept for learning – can make the discipline more comprehensible and attractive to students.

A diagrammatic technique helps to avoid all this and democratizes the knowledge of our quantum world. After all, the future quantum workforce must be trained earlier than ever, given we do not want students missing out on the quantum revolution. In addition, quantum computing is not the purview of physicists alone. Many computer scientists and programmers, who will never be formally trained in physics, will need an initiation in quantum mechanics.

When it comes to making education accessible and within the direct grasp of millions of eager learners, demystifying traditional modes of learning and introducing new approaches helps students and teachers. Learners gain the confidence to ask questions, synthesize connections between bodies of knowledge and prepare themselves for a workforce that may require competency instead of a paper degree.

According to a survey of students who completed the course, 60% engaged in interactive discussions or used the chalkboard to solve problems while 80% asked or responded to questions. For most of these students, this level of engagement with the instructor was a first in their lives. This is the confidence that our liberated students walked away with as they completed their final exams in the Quantum in Pictures summer school.

The post How pictures can help school students learn quantum physics appeared first on Physics World.

A laser plasma accelerator (LPA) has been used to power a free electron laser (FEL) for more than eight hours, delivering stable pulses of coherent light. The system was created in the US by researchers at the company Tau Systems and Lawrence Berkeley National Laboratory. The team says that its achievement represents a major breakthrough in stability for LPA-driven FELs, which could someday make coherent UV and X-ray pulses more accessible to academia and industry.

An FEL creates bright pulses of coherent light – usually in the ultraviolet-to-X-ray portion of the electromagnetic spectrum. These pulses are used in a wide range of research including physics, chemistry, biology and materials science.

The pulses are created by sending bunches of high-energy electrons through a device called an undulator, which applies a transverse magnetic field that alternates in direction as the bunch propagates. As the electrons are accelerated back and forth by the field they emit light. Under the right conditions the emitted light interacts with the electron bunch in such a way that the coherence and brightness of the light increases as the electron bunch travels through the undulator.

FELs require a bright and stable source of high-energy electron bunches, so today’s facilities are driven by large and expensive electron accelerators. The European X-ray Free Electron Laser, for example, is located at the end of a 3.4 km linear accelerator.

Surfing a plasma wave

High-energy electron bunches can also be created by firing high-intensity laser pulses at a plasma target. Electrons in the plasma are much lighter than the ions, so they are accelerated more by the intense electric field of the laser pulse. The result is a region of separated positive and negative charge that contains a large electric field. This region trails the laser pulse like the wake of a ship – and is called a wakefield. If electrons are injected into this wakefield, they are captured and accelerated to near the speed of light. The process is similar to how a surfer is propelled by an ocean wave.

While LPA-driven FELs would require expensive lasers, their size and cost would dwarf that of accelerator-driven facilities. Today, however, the electron pulses delivered by LPAs are not good enough to drive a FEL. Some shortcomings are related to fluctuations in the focal point of the laser and well as changes in the pulse energy and duration. These fluctuations can be caused by mechanical vibrations, temperature fluctuations and other environmental disturbances.

Founded in 2021, the Texas-based company Tau Systems is developing practical LPAs for a range of applications including FELs. Now, the company has joined forces with researchers at Berkeley Lab’s BELLA Center to implement a set of laser-stabilization technologies on BELLA’s Hundred Terawatt Undulator beamline.

The team implemented five active systems that worked together to stabilize the focal point of the powerful laser. Some of this was done using a “ghost” beam – a low-power copy of the driving beam – to observe subtle fluctuations that would not be apparent by monitoring the main beam.

High-quality bunches

As a result the system delivered bunches of 100 MeV electrons at a frequency of 1 Hz and at high stability for over 10 h. These bunches were then used to drive  a self-amplified spontaneous emission (SASE) FEL based on a 4 m-long undulator that is embedded within a vacuum chamber.

The LPA–FEL delivered violet (420 nm wavelength) pulses for more than 8 h without any human intervention. The FEL gain of the system was about 1000, which is the ratio of brightness of the emitted coherent FEL pulse to the brightness of light emitted by unamplified undulation.

This run is a significant improvement on the team’s 2025 achievement of using a LPA–FEL setup to deliver pulses of similar quality for an hour.

“This is the moment the community has been working toward,” says  Stephen Milton of Tau Systems. “We have shown that an LPA-driven FEL is not just a proof-of-concept experiment. It is a platform capable of delivering the stability that real scientific and industrial users demand.”

Finn Kohrell of the BELLA Center adds, “Maintaining FEL stability for a record eight hours represents a significant advancement in LPA-driven FELs and provides deeper insights both into achieving optimal FEL performance and into validating LPAs as high-brightness injectors, which is crucial for LPA application in future light source facilities”.

During operation, the team gathered data about the stabilization process and mapped correlations between the parameters of the drive laser; the plasma source; the electron bunches; and the FEL’s output pulses.  The researchers are now using this information to improve their control systems and they say that these data indicate that further gains in stability and brightness are possible.

The next experimental step will involve increasing the FEL energy to their system’s maximum value of 500 MeV.

“At this level, we can lower the undulator radiation wavelength to the 20–30 nm range, placing it in the hard ultraviolet or soft X-ray regime,” explains Kohrell. “[This would be] a crucial step toward making the technology viable for real-world applications.”

The new system is described in Physical Review Accelerators and Beams.

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Stanford Medicine has opened a new proton therapy facility – featuring an ultracompact treatment system that’s small enough to fit in a room the size of a conventional linear accelerator vault.

Proton therapy is an advanced cancer treatment that offers precise tumour targeting while minimizing dose to healthy tissues. The technique is particularly beneficial for treating tumours located near critical structures and for treating cancers in children. Currently, however, access to proton therapy is limited by its high costs and substantial space requirements.

The new treatment facility – opened earlier this week at Stanford Medicine Cancer Center in Palo Alto, CA – incorporates the S250-FIT proton therapy system from Mevion Medical Systems, the most compact cyclotron in the industry. But even with a much small accelerator, proton therapy delivery usually requires a bulky gantry that rotates around the patient to aim the proton beams at the optimal treatment angles. As such, most proton facilities need a whole new multi-storey building to be built just to fit everything in.

To eliminate this obstacle, the Stanford facility is using a positioning system from Leo Cancer Care to deliver protons via a novel approach known as upright radiotherapy. Here, the patient is treated in an upright position (rather than lying down) and rotated in front of a static treatment beam, removing the need for a gantry and slashing space requirements and installation costs.

By combining these advanced technologies, the new equipment fits into a standard 1200 sq. ft linear accelerator vault (as used for standard X-ray-based radiotherapy) and was installed without having to construct a new building.

The advanced system also incorporates built-in CT scanning, enabling extremely precise targeting of tumours within patients with minimal collateral damage to the rest of the body.

“Developing this novel approach to proton therapy at Stanford Medicine, in collaboration with our industrial partners Mevion and Leo Cancer Care, gives us an important additional tool to treat our patients in a personalized, case-by-case way,” says Billy Loo, professor of radiation oncology and co-director of particle therapy at Stanford Medicine. “We are excited to pioneer this world’s first ultracompact and efficient technology that will benefit not only patients at Stanford but expand access to proton therapy worldwide and improve patient outcomes.”

“This milestone really marks the transition from concept and theory to clinical reality,” adds Leo Cancer Care’s CEO Stephen Towe. “Proton therapy installed inside a linac vault always felt like an impossible goal – our partnership with Stanford and Mevion has made that vision possible.”

Loo tells Physics World that patient treatments on the new proton therapy system are likely to start this summer. “As with any first-of-its-kind system in medicine, introducing this complex technology requires a rigorous process of testing and optimization to ensure it meets our high standards for patient safety and treatment quality,” he explains. “We are moving through these steps now.”

The Stanford Medicine team emphasize the particular advantages of proton therapy for children, not least that it can really decrease the radiation dose delivered to normal tissues. Minimizing irradiation of sensitive developing tissue can dramatically reduce the risk of long-term side effects. In addition, treating children while they are sitting up and actively engaged may be far less intimidating for them than having to lie down and have the treatment “happen to them”.

The first proton treatments will likely be “cranial and head-and-neck sites, for both adults and selected paediatric patients, for which we already have established patient positioning solutions,” says Loo. In parallel, the radiation oncology team will develop the workflows and immobilization solutions for all other anatomic sites.

The team also plans to investigate new ways to advance the technology and explore the clinical advantages of delivering upright radiotherapy. For example, evidence suggests that for some diseases, such as lung cancer, upright treatment puts the targeted organ in a more favourable position to irradiate safely. Upright positioning also provides greater flexibility to deliver radiation from many different angles. The team will also study the impact of upright positioning on FLASH treatments, in which radiation is delivered at ultrahigh dose rates.

Looking ahead, nine other medical centres are installing this new ultracompact proton therapy system, ultimately making proton therapy increasingly accessible to patients around the world.

“The clinical data to support the use of protons is stronger than ever before,” says Towe. “The strength of this data, combined with the cost reductions delivered by Leo’s technology, has sparked a new wave of growth for protons globally.”

The post Stanford Medicine unveils world’s first ultracompact proton therapy facility appeared first on Physics World.

Scientists in the US have unveiled a new machine-learning tool that, they claim, can identify disruptive scientific breakthroughs. They say their method, which assesses how much a paper reshapes its field, is better than other techniques at spotting such disruptions even if they are simultaneously discovered by independent research groups (Sci. Adv. 12 eadx3420).

The work examined 55 million papers listed by Web of Science and the American Physical Society (APS) published between 1893 and 2019. The papers were mapped using a machine-learning technique known as neural embedding, with each publication represented by two vector points. The first vector characterizes the body of work the paper builds on while the second represents the research it inspires.

Papers that disrupt tend to cause future research to depart significantly from previous work in the field, making these “past” and “future” vectors diverge sharply. The greater the divergence, the higher the paper’s so-called Embedding Disruptiveness Measure (EDM) score.

The team, based at Indiana and Binghamton universities, tested their EDM technique against Nobel-prize-winning papers and milestone publications as selected by APS editors. The EDM identified these landmark contributions as being highly disruptive.

The researchers discovered that the EDM was more consistent at spotting such papers than similar metrics, such as the “disruption index”, which focuses more on a publication’s closest citations. While this makes it sensitive to individual citations, it can miss the bigger picture, the researchers found.

The team discovered that the 10 papers with the biggest difference between the EDM and the disruption index were all examples of “simultaneous disruption”. This is where multiple papers have independently reached the same conclusion, or scientists have published their work across publications. Citations that linked these simultaneous disruptive papers weakened their disruption index.

One notable example is the two 1974 papers announcing the discovery of the J/ψ meson. As both groups cited each other, the disruption index ranked these publications in the bottom 1% of disruptive papers while the EDM placed them both in the top 10%. A similar pattern was seen for the two 1964 papers – one by Peter Higgs and the other by François Englert and Robert Brout – on the Higgs mechanism.

The team claims that the EDM also provides a new way to detect simultaneous discoveries, finding that papers that report the same breakthrough tend to be cited in similar contexts by later work, meaning their “future” vectors cluster together.

“By having more accurate metrics, we can actually investigate where the disruption is happening in the map of science,” says data scientist Sadamori Kojaku from Binghamton University.

The researchers say their tool could help science funding and policy to drive transformative breakthroughs. “It can have significant implications for science policy and it’s also helpful for prioritizing funding,” adds Kojaku. “We now have the quantitative metrics to investigate at which stage of research the disruptive work occurs and matters most.”

The post Have you published a disruptive paper? New machine-learning tool helps you check appeared first on Physics World.

The physicist and venture capitalist Alexandra Vidyuk is our guest in this episode of the Physics World Weekly podcast. She is the chief executive and founding partner of Beyond Earth Ventures, which provides funding and support to early-stage companies in deep-tech sectors including space, robotics and energy.

In conversation with Physics World’s Margaret Harris, Vidyuk explains how her BSc in applied mathematics and physics and her early career in banking and fintech set her on a path to deep-tech venture capital.

Vidyuk talks about the specific challenges facing deep-tech entrepreneurs and reveals what she looks for when deciding which companies to fund. She also emphasizes the importance of building an organization that understands its customers and can communicate effectively with them.

The post Backing winners in deep tech: physicist and venture capitalist Alexandra Vidyuk appeared first on Physics World.

Here’s how the game works:

1. Enter a word guess – in this game the word has six letters.
2. After submitting your guess, each letter in the guessed word is coloured to provide feedback:
   • Green: The letter is correct and is in the correct position in the target word.
   • Yellow: The letter is correct but is in the wrong position in the target word.
   • Grey: The letter is not in the target word at all.
3. Using this colour feedback, refine your next guess.
4. Continue guessing until you correctly identify the hidden word(s) or run out of attempts.

If you need any hints, read this recent feature article.

Fancy some more? Check out our puzzles page.

The post Word wave puzzle no.2 appeared first on Physics World.

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The post Advent Research Materials wordsearch appeared first on Physics World.

Protein molecules are highly dynamic, continually changing shape in response to changes in external conditions. Scientists have long sought to mimic this behaviour in artificial materials, and now a team at the City University of New York (CUNY) in the US has done just that, constructing a crystalline solid that switches between several distinct architectures as the ambient humidity changes. Their work could make it easier to fabricate adaptive materials on a large scale for applications such as humidity-responsive coatings.

Proteins owe their shape-shifting character to a series of complex interactions that take place between two or more molecules. These supramolecular interactions, as they are known, allow proteins to adapt their properties – and therefore their functions – as needed. Water plays an important role in such interactions because it stabilizes certain structures while weakening others.

“Stripped-down” versions of protein behaviour

In the new work, researchers led by CUNY chemist Rein Ulijn and chemical engineer Xi Chen studied peptides, which are the molecular building blocks that make up proteins. In particular, they focused on leucine (L) and isoleucine (I), which are isomers, meaning they have the same chemical formula but different structures. “Such short peptides give us access to ‘stripped-down’ versions of protein behaviour,” explains Ulijn, who is also the founding director of CUNY ASRC Nanoscience Initiative. “They’re simple enough to design systematically, but still rich enough to encode sometimes surprisingly complex and dynamic behaviour.”

They found that when the chemical potential of water in the system – effectively, the humidity – changed, the solid-state porous architecture of LI crystals reorganized, reversibly switching between rigid perpendicular/parallel honeycomb structures and layered soft van der Walls structures. Importantly, Ulijn explains, this transformation occurs without compromising the peptides’ overall structural integrity.

“What makes this particularly significant is that most dynamic supramolecular systems are limited to relatively minor changes in organization,” he says. “In contrast, the peptide side chains in our system undergo very dramatic conformational reorganization, which translates into the topological changes observed.”

Uljin adds that this process offers a completely new way to design materials that can switch between distinct structural states. “This opens the door to solid materials that are both robust and highly adaptable, a combination that is difficult to achieve with existing approaches,” he tells Physics World.

A new toolbox for designing dynamic solid-state materials

The researchers say they undertook their study to address a “fundamental gap between biological systems and synthetic solid-state materials”. Although proteins routinely undergo sequence-encoded conformational changes to access multiple functional states in solution, replicating this kind of dynamic behaviour in solid materials has been a major challenge. “Our goal was to create a minimalist, peptide-based system that could mimic this adaptability without relying on large, complex structures and that could be triggered by low energy inputs,” they explain.

The team says the work provides a new toolbox for designing dynamic solid-state materials with tuneable topology and function, which could potentially impact a wide range of fields. One potential application is the development of adaptive materials with switchable mechanical properties, where stiffness and softness can be controlled through environmental humidity or temperature. “This could be useful in soft robotics, responsive coatings, or smart structural materials,” Chen notes.

The researchers are now studying other peptide structures in hopes of better understanding the fundamental rules for conformational control of short peptides. Ultimately, they say this programme should lead to specific design rules for porous peptide materials, making it possible to explore a broader range of sequences and side-chain chemistries. “We are also interested in scaling these materials to enable practical demonstrations in hydration-responsive coatings,” Chen adds.

The team reports its work in Matter.

The post Want to make a peptide material go from soft to stiff? Just add water appeared first on Physics World.

In a book about batteries, you might not expect the author to be detained by Congolese secret police because he attempted to meet a rebel warlord whose militia has been linked with cannibalism. But that’s exactly what happened when journalist Nicolas Niarchos was doing research for The Elements of Power: a Story of War, Technology and the Dirtiest Supply Chain on Earth.

In his debut book, Niarchos dives into the global supply chain of critical metals for lithium-ion (Li-ion) batteries. Nowadays Li-ion technology powers electric vehicles, laptops and smartphones, and provides backup for renewable energy when the Sun stops shining and the wind stops blowing. The critical metals in these batteries come from all corners of the Earth. In 2024 Australia, Chile and China were the top three producers of lithium; Indonesia produced over half of the world’s nickel; and the Democratic Republic of Congo (DRC) dominated the cobalt mining industry.

Building on his earlier reporting for The New Yorker and other outlets, Niarchos shines a light on the dark underbelly of green tech. He takes the reader from the underprivileged mining communities extracting the raw materials, to the global superpowers profiting from Li-ion technology.

This is a story of geopolitics, deep-rooted inequality, and history repeating itself. In recent decades, governments, corporations and opportunistic intermediaries have jostled for the lion’s share of resources in mineral-rich countries. As in colonial times, wealth has again concentrated in the hands of a few, while communities near the resources bear the costs of greed and corruption.

“The world is facing the biggest supply–demand dislocation in living memory with critical metals,” writes Niarchos.

The race to develop and commercialize

In The Elements of Power, Niarchos includes the history of Li-ion batteries and their commercialization. Key scientific figures include British chemist Stanley Whittingham, US solid-state physicist John Goodenough, and Japanese chemist Akira Yoshino, who all shared the 2019 Nobel Prize in Chemistry for their breakthroughs that led to commercial Li-ion batteries.

Whittingham laid the foundations in the 1970s when his work on fast ionic transport in solids led to a cathode made from titanium disulphide that could house (or “intercalate”) lithium ions. Goodenough then introduced a lithium cobalt oxide cathode – raising the battery voltage and making it less explosive – before Yoshino took the final step to a commercially viable battery by adding a carbon-based anode in 1985.

Niarchos highlights how Japan failed to capitalize on this early lead. Although Japanese firm Sony released the first Li-ion battery in 1991, production and commercial impetus soon switched to China and South Korea. In fact, at the turn of the millennium, Japan controlled 90% of the Li-ion market, but by 2012 Sony’s value had dropped to one-ninth of Samsung’s in South Korea.

The electrification of transport has been a key application of China’s push for Li-ion batteries – it drives economic growth and tackles air pollution. The speed of progress is striking. In 2018 China produced 1.26 million electric cars over the course of the whole year. By 2024 it was producing a million in a month.

To fuel battery demand, Beijing has steadily strengthened its foothold in places like the DRC and Indonesia. Niarchos highlights the 2007/2008 Sicomines “minerals-for-infrastructure” deal, which was a major, yet controversial, partnership made between the DRC government and a group of Chinese investors. It swapped massive copper/cobalt mining rights in the DRC for $6bn in Chinese-financed infrastructure, which has been slow to materialize.

Niarchos shows how China’s economic miracle has been fuelled by ruthless geopolitical pragmatism in strengthening its mining deals over decades, but also how the US administration’s manoeuvrings in places like Greenland are an unsubtle sign that it intends to catch up.

Inevitably, Elon Musk and Tesla make several appearances in the book. For example, Niarchos includes how a futuristic Tesla Gigafactory near Berlin, Germany, was attacked by protestors. The episode reveals the conundrum facing progressives in the West who want to go green but in the right way, led by the right people.

The people behind the metal

While Niarchos looks at how global superpowers profit from Li-ion technology, it’s his reporting on the sources of critical metals that reveals the truly dark side of the supply chain.

Cobalt, often used in Li-ion battery cathodes, is perhaps the starkest example of the problem, and the book gives particular attention to its production and the mining practices in the DRC. More than 70% of global supply comes from the DRC, with most mined in the mineral-rich Katanga region, comprising of the provinces Tanganyika, Haut-Lomami, Lualaba and Haut-Katanga. Extreme poverty is rife, cholera outbreaks are common, and conflict has displaced hundreds of thousands.

One of the book’s strengths is how Niarchos weaves the story of Li-ion batteries with the social history of the DRC. In works like this, the human sections often provide light relief from dense scientific explanations. Here, the opposite is true, as the cycles of violence and exploitation against the Congolese people – which goes back centuries – make for grim reading.

What is now the DRC was colonized in the 1870s by Belgium, and forced labour, starvation, violence and mass death were inflicted on the Congolese people in relation to the ivory and rubber trade. While the country gained its independence from Belgium in 1960, the turbulence of power struggles and civil war has led to deeper corruption, opaque webs of international finance, and foreign magnates whose dealings raise eyebrows among global watchdogs. Today the country seems haunted by its past, trapped by the cruelty of power dynamics and the corrupting influence of promised wealth.

The most resonant pages of The Elements of Power describe modern daily life in the Katanga region. Most people see barely a trickle of the vast mineral wealth they help dig up. In 2020 some 74 million Congolese lived below the poverty line of $2.15 a day, and 43% of children in the country were malnourished.

Many adults and children resort to digging for mineral seams using rudimentary tools and minimal safety gear. Referred to as “artisanal” miners by multinational corporations but known as creuseurs (French for digger or burrower) in the DRC, they often come from the very poorest stratum of society and do not have the education or the contacts to get jobs with the mining corporations that have official permits to extract the cobalt. Just in Kolwezi – the capital city of the Lualaba Province with a population of nearly 600,000 – an estimated 170,000 of these unofficial miners dig for the black ores, which they then sell to unscrupulous intermediaries.

One of the saddest passages is when Kolwezi resident Françoise Ilunga describes how her husband was crushed and suffocated, along with at least 150 other creuseurs, after a tunnel collapsed in the city. Unable to get official jobs, the miners had entered a secluded part of a cobalt mining site without permits or safety gear to find ore to sell so they could support their families. The mine was run by the Anglo-Swiss multinational Glencore (which incidentally had to pay $700m in 2022 relating to bribery offences in several African nations). Françoise and her family spent two days digging up her husband’s body.

It is easy to see how cycles of poverty have been sustained in the DRC. Niarchos interviews children who say they mined out of necessity for food and clothes. In their villages and towns, conflict still bubbles under. When Niarchos is detained by the DRC’s secret police, he had planned to meet a man called Gédéon, whose militia group, Bakata Katanga, has agitated for a separate Katanga state. Niarchos had heard a rumour that Gédéon was funding himself through artisanal mines. You’ll need to read the book for the full story, but it’s fair to say Niarchos won’t be returning to the DRC anytime soon.

Save solutions for another day

While The Elements of Power touches upon some solutions – such as recycling batteries, and sodium and sulphur-based alternatives to Li-ion batteries – no fully scalable solution is presented. And at times, I found the web of organizations and individuals hard to follow. I’m also a bit of a geology geek so I wish there was a bit more on why the DRC is blessed with so many critical minerals in the first place.

That said, the book feels incredibly timely given the current state of geopolitics. It is essential reading for anyone who cares about the origins of materials powering their phones, cars and many other aspects of daily life in wealthy nations. It shines a light on how difficult it is to know what percentage of critical minerals in your devices has come from ethical sources, despite what tech companies might say.

If there is a key takeaway, it’s that any system-wide solution for greener, ethical mining must consider the entire supply chain. Above all, we should listen to people on the ground sourcing the raw materials that make our shiny new technology possible. A supply chain is only as clean as its grubbiest link.

• 2026 William Collins 480pp £25 hb

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Most materials expand when heated because increased atomic vibrations push atoms slightly farther apart. However, some unusual materials, such as α‑Cu₂V₂O₇, instead shrink when heated, a phenomenon known as negative thermal expansion. Although this behaviour had been observed before, its underlying mechanism was not well understood. In this study, the researchers examined α‑Cu₂V₂O₇ from 5 K to 800 K using neutron diffraction, synchrotron X‑ray diffraction, Raman spectroscopy, and first‑principles calculations. They found that the material exhibits three distinct thermal‑expansion regimes: almost no expansion below 35 K, strong negative thermal expansion between 35 K and 550 K, and normal positive expansion above 550 K.

The origin of this behaviour lies in how copper atoms move within distorted CuO₆ like octahedra. At the lowest temperatures, a quantum effect called the second‑order Jahn-Teller effect pushes the copper atoms off‑centre, but this motion is partly suppressed by the onset of antiferromagnetic ordering, which stabilises the structure and produces near‑zero thermal expansion. As the temperature increases, the second‑order Jahn-Teller effect weakens, allowing the copper atoms to shift back toward the centre of their octahedra, but in opposite directions along different structural chains. This anti‑off‑centering motion compresses the Cu-Cu zigzag chains and also reduces the spacing between neighbouring chains, pulling the structure inward and producing the observed negative thermal expansion.

The researchers also found that the copper atoms have unusually large vibrational freedom along one axis, which helps enable this motion. Raman spectroscopy revealed an anomalous broadening of a low‑frequency vibrational mode, providing evidence for electron-phonon coupling that further supports the proposed mechanism. Together, these effects explain the unusual thermal behaviour of α‑Cu₂V₂O₇ and offer valuable insight for designing materials with controlled thermal expansion, which is important for precision engineering, electronics, and composite materials that must remain dimensionally stable across temperature changes. Meanwhile, this mechanism, centered on the Jahn–Teller effect, can be extended to a wide range of transition metal oxide systems, providing a universal theoretical foundation for systematically explaining the anomalous thermal expansion behavior of such materials.

Do you want to learn more about this topic?

Negative thermal expansion and associated anomalous physical properties: review of the lattice dynamics theoretical foundation by Martin T Dove and Hong Fang (2016)

The post A new explanation for negative thermal expansion appeared first on Physics World.

In this work the researchers explore what happens when a topological insulator is placed next to a two‑dimensional ferromagnetic insulator. Experiments have shown that this arrangement dramatically increases the ordering temperature of the ferromagnet. The theoretical study demonstrates that the surface electrons of the topological insulator mediate interactions between the magnetic moments in the neighbouring ferromagnetic material, strengthening its overall magnetism.

There are two main ways electrons in a nearby material can act as messengers between magnetic moments. The first is the well‑known Ruderman-Kittel-Kasuya-Yosida interaction, which arises in a metal from electrons at the Fermi level that produce long‑range, oscillatory coupling, typically in a regime when magnetic moments are sparse. The is the often overlooked Bloembergen-Rowland interaction, which in fact turns out to dominate in this system. This mechanism comes from virtual transitions between the valence and conduction bands of the topological insulator surface states and leads to strong, short‑ranged ferromagnetic interactions between the dense magnetic moments.

Identifying the Bloembergen-Rowland interaction is significant because it naturally enhances ferromagnetism: it is strong, it does not oscillate, and it keeps the magnetic moments aligned. Due to the spin-momentum locking of the topological insulator’s surface states, this interaction also has a built‑in anisotropy that favours out‑of‑plane magnetic alignment. The researchers show that the increase in the magnetic ordering temperature is directly proportional to the Van Vleck susceptibility of the topological insulator’s surface electrons.

The study also examines how hybridisation between the top and bottom surfaces of a thin topological‑insulator film modifies the mediated interaction and affects the magnetic ordering temperature. This analysis helps explain recent experimental results in heterostructures made from chromium telluride and bismuth-antimony telluride. Overall, the work clarifies how topological surface states influence magnetism in these layered systems and provides a foundation for designing improved devices in spintronics, magnonics, and quantum technologies.

Do you want to learn more about this topic?

Characteristics and controllability of vortices in ferromagnetics, ferroelectrics, and multiferroics by Yue Zheng and W J Chen (2017)

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Graphene liquid cells have been used to study atoms dissolved in organic solvents at atomic-scale resolution. Through a combination of smarter material choices and machine learning techniques, a team led by Sarah Haigh at the University of Manchester showed how these graphene “nano-aquariums” can work with virtually any type of solvent – offering deeper insights into the atomic-scale properties of solids left behind when solvents dry out.

To understand the atomic interactions taking place at solid–liquid interfaces, researchers will often start by sandwiching liquid samples between pairs of transparent films. In most cases, they will then use transmission electron microscopy (TEM) to create atomic-scale images of these interactions. This involves irradiating the sample and films with a tightly focused electron beam.

“These windows need to be as thin as possible to get the best resolution,” explains Manchester’s Nick Clark. “Graphene is just about the thinnest window possible, and over the past decade or so it’s enabled atomic-resolution imaging of solid nanoparticles inside liquids.”

Uncontrollable evaporation

So far, however, these graphene liquid cells have proven difficult to work with. While sealing liquid samples inside these cells, the solution will often evaporate uncontrollably, creating significant variability in the sample’s concentration. In addition, most organic solvents are incompatible with the soft polymer membranes used to support the graphene films during the sealing process, limiting previous studies to mild aqueous solutions.

To address these challenges, Haigh’s team replaced the polymeric supports with stiff ceramic cantilevers. These offer similar levels of mechanical stability while being far more chemically inert. As a result, the cells can be sealed mechanically while fully immersed in liquid. This prevents the sample from drying out during sealing, while also making the process compatible with virtually any solvent.

The resulting graphene cells are remarkably stable, which allows the team to collect large numbers of images via repeated irradiation by the TEM electron beam.

“We combined this with neural-network based denoising to minimize the signal to noise ratio required to extract atomic coordinates, and a fully automated analysis workflow,” Clark adds. “This enabled us to collect enough atomic coordinates to draw representative conclusions.”

Individual gold atoms

With this combination of techniques, the team could resolve individual gold atoms and the graphene lattice beneath them, and examine how the behaviour of gold atoms at the graphene-liquid interface varied with their choice of organic solvent.

With their rapid TEM imaging, they could track over one million gold adatoms – single atoms which adsorb to a solid surface – and account for the dynamic, interconnected behaviours of structures formed from pairs, triplets, and larger clusters of adatoms.

Chemists have long known that these behaviours are strongly connected to the catalytic properties of the solid material left behind when the solvent dries out. For the first time, however, this approach allowed Haigh’s team to explore in detail how these properties depend on the choice of solvent.

“We were able to decouple the actual liquid phase dispersion from the drying process, and showed how both must be controlled to generate isolated atoms on the final dried support – which we know gives the most active catalytic materials,” Clark explains.

Through further improvements to their technique, Haigh, Clark and their colleagues are confident it could drive advances across a range of real-world technologies. “We hope that our new characterisation approach will allow us to help those working on catalysis, or batteries, or liquid filtration to understand what’s happening at the solid-liquid interfaces in their devices at atomic scale,” Clark says.

The research is described in Science.

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Researchers in France have developed a novel method to investigate how pollen is dispersed from trees when the wind blows – paving the way for new approaches to urban planning that could help alleviate the symptoms of seasonal hay fever.

A project team headed up at the University of Rouen Normandy has discovered for the first time that different trees can exhibit different local dynamics for the transport of pollen grains – for example, when pollen is dispersed by wind – and that that this behaviour depends on the local detachment force of pollen grains occurring at the scale of each flower inside the tree.

As part of the project, outlined in the paper Flow and plants: On the dispersion of wind-induced tree pollen, published in Physics in Fluids, the researchers developed an innovative direct-forcing porous immersed boundary method (DF-PIBM) to explore the wind-driven pollen dispersion and transport phenomena from green trees.

“The research investigates, through advanced physics-based modelling and simulations, the impact of tree types and their interaction with wind on the local dispersion of pollen grains in the surrounding environment,” says lead author Talib Dbouk, a researcher in the CORIA Lab, CNRS, at the University of Rouen Normandy.

As Dbouk explains, the team’s approach involved the use of a range of advanced computational fluid dynamics (CFD) modelling and simulation techniques to solve the local air flow around and within the trees, taking into account the interaction between the air flow and the pollen grains in and/or on the tree flowers.

“The DF-PIBM is an advanced numerical technique developed in order to accurately solve the local resistance of a tree to wind by assuming the tree leaves lead to the fact that a tree can [act] as a porous medium, where the local porosity inside the tree will depend on its leaf area density,” he adds.

According to Dbouk, this method was “derived, implemented and validated in an in-house CFD code”, first by testing different flow configurations around and within porous spherical particles – and then by extending and applying it to different types and structures of trees.

A digital twin

In Dbouk’s view, the key advantage of using DF-PIBM compared with other approaches is that it allows researchers to accurately solve the local air flow velocity and the local pressure inside the tree.

“DF-PIBM has a number of current and potential applications – including prediction of the behaviour of airborne pollen grains and support for future applications involving vegetation–flow interactions in urban settings,” he says. “The currently developed DF-PIBM allows us to accurately predict all the phenomena of the detachment, dispersion, resuspension and local transport of airborne pollen grains when emitted from a green space – for example, trees and grass – and thus any vegetation zones inside urban environments under different weather conditions.”

Meanwhile, co-author Julien Reveillon confirms that the next steps for the research team will involve the integration of all its physics-based models into a new advanced digital twin of the Rouen-Normandy Metropolitan region in Normandy, France.

“This is with the intention of developing a new advanced multi-risk assessment digital platform that can help our local public authorities in their future territorial management and planning strategies – for example, to better anticipate and fight climate change phenomena, especially those related to local heat islands and aero-allergens like pollen, in addition to environmental pollution of air, water and soil,” he says.

“Moreover, huge efforts are also [being] made in order to develop and integrate advanced models related to predicting and simulating airborne pollutant particle dispersion in our region, for example those related to emissions from both natural fires and industrial accident fires,” co-author Béatrice Patte-Rouland tells Physics World.

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Pristine iron telluride is a superconductor, with the natural material’s superconductivity suppressed by excess iron in the crystal lattice, researchers in the US have shown. This resolves a long-standing puzzle about why, when other materials with similar structures showed superconductivity at low temperatures, iron telluride had always retained an antiferromagnetic order. The results provide a secure platform for further exploration of iron-based superconductivity, and could open the door to the study of interesting physics such as potential topological superconductivity in iron telluride itself.

Much like the cuprates, iron-based superconductors such as chalcogenides like iron selenide often exhibit complex phase diagrams in which antiferromagnetic ground states compete with superconducting ones. Although tellurium sits directly underneath selenium in the periodic table, superconductivity has never been observed in pure iron telluride. It can behave as a “parent compound” for inducing superconductivity via chemical substitution with selenium, for example.

“One thing that’s always been a puzzle in the field is that the magnetic structure of iron telluride is fundamentally different from that of all other iron-based superconductors,” says condensed matter physicist Pengcheng Dai of Rice University in Texas; “People say ‘Oh, it’s more correlated’ – but the problem with that is that when you dope it with selenium and it does become superconducting, all the electric and magnetic properties occur at the exact same wave vector as other iron-based superconductors.”

Barely discussed

Condensed matter experimentalist Cui-Zu Chang of Pennysylvania State University in the US and colleagues had conducted multiple experiments involving the growth of tellurium compounds on iron telluride substrates, and reliably found that these produced supercondivity. Nevertheless, says Chang, the possibility that iron telluride itself might have a superconducting state was barely discussed by theorists.

Following Chang’s philosophy that “for superconductivity, if you follow theory and try to do something, 99% of the time you will fail,” the researchers set out to ascertain the state of pristine iron telluride experimentally. They bombarded a strontium titanate substrate with high purity beams of gaseous iron and tellurium atoms to produce 40-layer-thick films of iron tellurium. When they examined these using a scanning tunnelling microscope, they found that the films showed antiferromagnetic order. However, electron microscopy showed that the structures contained excess iron atoms clustered together periodically.

The researchers therefore performed multiple cycles of post-growth annealing, bombarding the structure with pure tellurium. These reacted with the interstitial iron, removing it from the structure by forming more iron telluride on the surface. The researchers monitored the electrical behaviour of the sample in tandem with its structural evolution, finding that, as regions approached stoichiometric FeTe, the antiferromagnetic order disappeared. After five cycles of annealing, the material was pure iron telluride, and the researchers showed that it behaved as a robust superconductor with a critical temperature of around 13.5 K. They confirmed this with the observation of the Josephson effect, Cooper-pair tunnelling and other related phenomena.

The researchers now intend to study the specific properties of stoichiometric iron telluride in more detail: “Because tellurium is heavier than selenium you have stronger spin-orbit coupling, so iron telluride should be a topological insulator at the same time as it’s a superconductor,” says Chang;  “We call these topological superconductors.” Such topological superconductors – the first of which was uranium ditelluride – are of great interest in quantum computing thanks to their potential to host protected Majorana qubits. More broadly, the researchers believe it is important to study whether other materials may host “hidden” superconducting states suppressed by disorder.

Dai, who was not involved in the research, is impressed: “It’s surprising, in the sense that it solves a fundamental puzzle that’s been in the field for some time,” he says. He notes that definitive proof is not achieved because the material is on a substrate, so techniques such as neutron diffraction traditionally used to probe the magnetic structure of bulk materials are impossible. It is also possible to question whether the substrate is influencing the material. Nevertheless, he is persuaded: “At least to me, it really unifies the picture that the magnetism is probably universal for all the iron-based superconductors,” he concludes; “In the same way that in the cuprates, the parent compounds are basically Mott insulators, from this experiment we can basically say that in iron-based superconductors the parent compounds are basically simple stripes, and this oddball is because of the excess iron that stabilizes the particular structure.”

The research is described in Nature.

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There are today two main ways to measure the Hubble constant, which is a parameter that describes the rate at which the universe is expanding. However, these two techniques produce conflicting results This discrepancy is called the Hubble tension and it suggests that we may be missing something fundamental about how the universe works. Now, two independent groups of astronomers, one in the US and the other in Germany, are developing two new methods to measure the Hubble constant. One uses gravitational waves; and the other uses gravitationally-lensed supernovae. Their work could help resolve the Hubble tension.

We know that the universe has been expanding ever since the Big Bang nearly 14 billion years ago – in part, thanks to observations made in the 1920s by the American astronomer Edwin Hubble. By measuring the redshift of various galaxies, he discovered that galaxies further away from Earth are moving away faster than galaxies that are closer to us. The linear relationship between this speed and the galaxies’ distances is defined by the Hubble constant, H₀.

While there are many techniques for measuring H₀, the problem is that different techniques yield different values. One main approach involves the European Space Agency’s Planck space telescope, which measures the Cosmic Background Radiation (CMB) “left over” from the Big Bang. This produces a value of H₀ of about 67km/s/Mpc, where 1 Mpc is 3.3 million light–years. The other main approach is the “cosmic distance ladder” measurement, such as that made by the SH0ES collaboration involving observations of type Ia supernovae, which says H₀ is about 73 km/s/Mpc.

Much brighter than typical supernovae

Now, astronomers at the Technical University of Munich, the Ludwig Maximilians University and the Max Planck Institutes for Astrophysics and Extraterrestrial Physics have observed an extremely rare type of supernova – or stellar explosion – that was gravitationally lensed, which by itself is also a very rare phenomenon. The supernova, which is called SN 2025wny (or more affectionately “SN Winny”), is superluminous and therefore much brighter than most gravitationally lensed supernovae discovered to date. This means that it can be studied using ground-based telescopes. Indeed, the researchers, led by Sherry Suyu and Stefan Taubenberger observed it with the Nordic Optical Telescope and the University of Hawaii 88-inch Telescope.

“It was an extraordinary coincidence that the first well-resolved lensed supernova found from the ground turned out to be a superluminous supernova,” says Taubenberger. “Its initial spectrum did not match the types of supernova we expected (that is, Type Ia or Type IIn), so determining its redshift was also difficult without this clear classification. We eventually measured the redshift to be equal to two so the observed optical light had actually been emitted as energetic UV radiation. The extraordinary UV brightness then allowed us to identify the object as being a superluminous supernova.”

The fact that the supernova can be clearly observed from here on Earth makes it useful for a technique called time-delay cosmography. This method, which dates from 1964, exploits the fact that massive galaxies can act as lenses, deflecting the light from objects behind them so that from our perspective, these objects appear distorted. “This is called gravitational lensing and we actually see multiple copies of the objects,” Taubenberger explains. “The light from each of these will have taken a slightly different pathway to reach us, so we see them at different times. In the case of SN 2025wny, we observed five copy objects that had been deflected by two galaxies in the foreground.”

If we measure the difference in the arrival times of these objects and combine these data with estimates of the distribution of the mass of the deflecting lens galaxies, we can calculate the so-called time-delay distance, he explains. “From the time-delay distance and the redshift, we can then infer H₀. Unlike the cosmic distance ladder, which involves many calibration steps and can accumulate errors with each step, this is a one-step technique with fewer and completely different sources of systemic uncertainties.”

Making the observations was not without a number of challenges, he remembers. “Initially, we had secured observing time at southern hemisphere telescopes (in particular, the ESO [European Southern Observatory] in Chile). However, the object we discovered was in the northern sky, making this secured time unusable. This meant we had to quickly find alternative observatories and write new proposals for northern hemisphere follow-up observations.”

Using undetectable black hole collisions

Meanwhile, a team of astrophysicists at The Grainger College of Engineering at the University of Illinois Urbana-Champaign and the University of Chicago has developed a way to determine the Hubble constant using gravitational waves and in particular the gravitational-wave background. Gravitational waves are generated when compact astrophysical objects, such as black holes, collide. These collisions, which are extremely energetic, produce tiny ripples in the fabric of space–time that travel at the speed of light, eventually reaching us here on Earth where they are detected by the LIGO–Virgo–KAGRA (LVK) Collaboration.

Individual black hole collisions have been observed by the LVK, which allows us to determine the rates of those collisions happening across the universe, explains study leader Bryce Cousins, who is at Illinois. “Based on those rates, we expect there to be a lot more events that we can’t observe. This is called the gravitational-wave background.”

Their approach uses a unique, previously unexplored relationship between the gravitational-wave background and H₀.  This relationship is not found in other astrophysical phenomena, meaning that the method is complementary to existing electromagnetic and gravitational-wave measurements of H₀.

An upper limit on the background can provide a lower limit on the Hubble constant

The strength of this gravitational-wave background scales directly with the density of gravitational waves in the universe, he says. “For example, if the universe were expanding more slowly, then it would have a smaller total physical volume and a correspondingly higher density of gravitational waves, leading to a stronger background. Thus, an upper limit on the background can provide a lower limit on the Hubble constant.”

The researchers demonstrated their hypothesis by analysing gravitational-wave data from the LVK Collaboration’s third observing run. They have dubbed their method the “stochastic siren” since the gravitational waves (the “sirens”) composing the background arise randomly.

The LVK network is not yet sensitive enough to detect the gravitational-wave background, but researchers expect it will be able to within the next six years or so. However, when Cousins and colleagues’ new work is combined with existing “spectral siren” measurements, the result is a more accurate value of H₀ – even without a detection of the gravitational-wave background. As a result, the new technique should only improve as gravitational-wave detectors become more sensitive. The spectral siren approach measures the Hubble constant by considering the redshift of gravitational-wave signals.

Cousins says he is “hopeful” that the findings of gravitational-wave cosmology will be able shed more light on the Hubble tension as gravitational-wave data collection continues.

The researchers are now extending their method to consider other dark energy models, in light of ongoing findings that the standard “cosmological constant” interpretation of dark energy may be incorrect. Cousins is also applying the existing analysis to the latest gravitational-wave dataset and working with other collaborators to modify the stochastic siren procedure so that it can be applied to the next-generation of gravitational-wave detectors.

Two different but complementary techniques

Taubenberger says that Cousins and colleagues’ technique is trying to measure the Hubble constant in a completely different way to his group’s – and also without relying on the cosmic distance ladder. “Since some gravitational waves have no optical counterpart, you cannot take an optical spectrum of them and measure their redshift, so methods like theirs allow us to measure distances in a statistical sense by analysing multiple objects and glean information about the Hubble constant in this way.

“Every independent approach to measure the Hubble constant is welcome, of course.”

Cousins, for his part, says that Taubenberger and colleagues’ work effectively supports an existing method with new data, while his group’s work involves creating a new method that can use existing data. “Taubenberger and his team exclusively use electromagnetic data, which differs from our gravitational wave method, but our approaches are ultimately complementary since they are independent takes on the same underlying question.

“It is interesting and important work since they have found a unique candidate for time-delay cosmography. I am excited to find out what new Hubble constant constraints will come from using this new lensed supernova.”

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Fancy some more? Check out our puzzles page.

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This episode of the Physics World Weekly podcast features Brian Pogue, who is professor of biomedical engineering at Dartmouth College in the US. He is also the co-founder of several start-up companies that are developing optics-based systems for medicine.

In conversation with Physics World’s Tami Freeman, Pogue explains that optical technologies underlie many of today’s routine medical procedures. The field of optics is also converging with the world of medical physics, and Pogue talks about exciting new techniques for guidance, dosimetry and in vivo verification of radiation therapy cancer treatments.

• This interview was recorded in association with the journal Physics in Medicine & Biology, which celebrates its 70th anniversary this year.

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NASA has successfully launched four astronauts on a 10-day mission to the Moon. The crew – Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen – were aboard the Orion spacecraft that was launched yesterday by a Space Launch System rocket from NASA’s Kennedy Space Center in Florida.

The mission is the first crewed lunar flyby in more than 50 years but it also represents a number of significant firsts with Koch, Glover and Hansen set to be the first woman, Black person and Canadian, respectively, to travel to the Moon.

Following launch, the Orion capsule was put into Earth orbit and after five hours into the flight, the craft deployed four CubeSats – from Argentina’s Comisión Nacional de Actividades Espaciales; the German Aerospace Center; the Korea AeroSpace Administration; and the Saudi Space Agency – that will conduct scientific investigations and technology demonstrations.

The craft is now set to carry out a six-minute rocket firing that will send the spacecraft towards the Moon.

During a lunar flyby on 6 April, the astronauts will take photographs and provide observations of the Moon’s surface being the first people to see some areas of the far side.

Some four days later, the craft will then return to Earth and splash down in the Pacific Ocean.

This mission follows the Artemis I mission, which carried a simulated crew of three mannequins wired with sensors, that completed a flyby of the Moon in 2022.

Artemis III, meanwhile, is currently ear-marked for launch in 2027, planning to be the first crewed lunar landing since the Apollo missions in the 1960s and 70s.

The post NASA launches crewed Artemis II mission to the Moon appeared first on Physics World.

How did you get on?

14 words Warming up nicely

20 words Getting hot, hot, hot

26 words Top dog!

Fancy some more? Check out our puzzles page.

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A new integrated photonics platform can perform precision quantum experiments that were previously only possible with multiple table-top lasers and other bulky apparatus. According to its US-based developers, the new chip-scale device could find applications in quantum computing and portable optical clocks based on trapped ions.

Today’s quantum computers and optical clocks depend on a range of equipment that typically includes some combination of lasers, cryogenic coolers, vacuum chambers and optical reference cavities. The last of these can take up more than half the device’s total volume, and they are crucial for stabilizing laser frequencies to the high precision required for controlling the quantum states of trapped ions. Such ions can serve as quantum bits (qubits) in quantum computing and can also be used for precision timekeeping in optical clocks. In the latter case, each clock “tick” is defined by the frequency of the light the ions absorb and emit as they undergo a specific, sub-Hz transition (the so-called “clock transition”) between atomic energy levels.

Miniaturizing large laser systems

Researchers led by Daniel Blumenthal of the University of California Santa Barbara (UCSB) and Robert Niffenegger at the University of Massachusetts Amherst have now shown for the first time that these large, stabilized laser systems can be replaced with small photonic chips. They used these chips to prepare and control the quantum state of strontium ions at room temperature as well as driving the clock transition. Though the fidelity of the system is not yet high enough to compete with the best traditionally-constructed devices, Niffenegger describes it as a critical first step for producing next-generation clocks and future quantum computers with millions of qubits. “Reaching such a goal will only be possible with such integrated quantum systems on a chip,” he explains.

Blumenthal, Niffenegger and colleagues used two components to create their chip-based stabilized laser: an integrated Brillouin laser with a wavelength of 674 nm, connected to an integrated 674 nm, 3 m long coil resonator cavity. The team characterized the stability of this laser and coil by measuring the 0.4 Hz quadrupole optical clock transition in strontium-88 (⁸⁸Sr⁺) ions trapped at an electrode located on a single surface electrode trap (SET) chip. This transition is one of the most precise used by quantum researchers today, and its narrow linewidth makes it relatively easy to measure using high-resolution trapped ion spectroscopy.

“The fact that these results were achieved with the SET at room temperature is remarkable given the precision of the transition, and is a major step forward in realizing portable versions of this quantum technology,” Blumenthal says.

Making optical clocks more portable and robust

As well as being smaller than traditional lasers, the chip’s 674-nm Brillouin laser light also removes the need for bulky frequency conversion equipment. A further advantage is its reduced high-frequency noise, which is important for clock acquisition and qubit state preparation fidelity, and which cannot be achieved using standard electronic feedback loops. The coil, for its part, reduces mid- and low-frequency noise, stabilizing the laser’s carrier frequency even further so that it can be locked to the precision sub-Hz trapped-ion clock transition.

According to Niffenegger, this combination of improvements enabled the team to achieve a frequency noise profile and so-called Allen deviation (a measure of stability) of just of 5.3 × 10^–13 – an unprecedented figure for a room-temperature chip. “We can therefore prepare qubit states with high fidelity and interrogate the clock transition, which is essential for quantum computing applications,” he says.

As optical clocks become more portable and robust, they become more feasible for a greater variety of applications. The ultimate goal, says Blumenthal, is to reach a stability range of 10^-14 to 10^-16, which would allow optical clocks to replace GPS-based navigation on missions to the Moon and Mars. “Such clocks could also help advance fundamental science – for example, by mapping gravity and measuring orbit time around Earth for climate science, detecting gravitational waves and dark matter/energy and for general relativity measurements, to name just a few,” he explains.

Niffenegger says it is now feasible to scale the team’s integrated platform to a grid of 100 or more ions, to further improve performance. He and his colleagues are now working to integrate other experimental components (including the ion trap chip, the optical cavity chip and other photonics) onto a single, full-architecture chip that builds on their current designs. “Preliminary results already show improved performance, with further exciting developments anticipated soon,” they tell Physics World.

The present work is detailed in Nature Communications.

The post Trapped ion quantum technology gets smaller appeared first on Physics World.

Photon-counting computed tomography (PCCT) is an advanced medical imaging technique that differs from conventional X-ray CT in that it can discriminate between the energies of individual detected photons. Offering higher spatial, spectral and contrast resolution than conventional CT, PCCT could deliver significant benefits for disease characterization and enable new diagnostic approaches.

Conventional CT measures the attenuation of X-rays after they pass through the body, enabling clinicians to monitor normal and abnormal anatomy and providing valuable information for diagnosis and treatment of disease. The advantages promised by PCCT primarily arise from the differing characteristics of the detectors: conventional CT scanners use energy-integrating detectors (EIDs) whilst PCCTs employ photon-counting semiconductor detectors.

The effective dose from diagnostic CT procedures is estimated to be in the range of 1–10 mSv, although this can vary by a factor of 10 or more depending on patient size, the type of CT scan performed, the CT system and the operating technique. PCCT systems offer better dose efficiency than conventional CT and use energy thresholding to eliminate background electrical noise. As a result, PCCT requires lower radiation dose than standard CT – reducing the risk to the person being scanned.

Detector characteristics: limitations and advantages

Conventional CT systems use an EID to collect the total energy deposited by all incident X-ray photons. EIDs are typically composed of gadolinium oxysulfide (Gd₂O₂S) or cadmium tungstate (CdWO₄) and comprise two layers: a solid-state scintillator placed on top of a photodiode array. The detection mechanism is a two-step, indirect process. Incoming photons hit the scintillation layer, which produces a flash of visible light. When the photodiode absorbs this light, it converts it into an electrical signal.

The photodiode array consists of individual detector elements separated by opaque, reflective walls called septa. This design prevents optical cross talk (signals transferring between adjacent channels and reducing image quality) produced by light scattering. The need for septa, however, creates “dead space” on the detector surface, which wastes X-ray dose and limits the spatial resolution since it physically restricts detector size.

As EIDs collect the total energy from all incoming photons, signals from photons of different energies are mixed together. High-energy photons will generate a higher light intensity than low-energy photons and will consequently produce a higher intensity electrical signal. This means that the final output signal will be dominated by the high-energy photons and under-weight the valuable contrast information that the low-energy photons provide. It also prevents the distinction between electrical noise and genuine low-energy photons, which further affects the achievable contrast.

PCCT scanners, on the other hand, employ photon-counting detectors that directly convert the photon energy to electric signals. These detectors consist of a semiconductor layer placed between a cathode on the upper side and an anode underneath. The anodes are pixellated to increase spatial resolution, with each pixel placed on top of an ASIC.

This detector uses a direct conversion process in which a high bias voltage is applied across the semiconductor to generate electron–hole pairs when struck by an incoming photon. The strong electric field draws the clouds of charge toward the anode electrodes, creating a current. The ASIC instantly processes this current and converts it into a voltage pulse, with the height of the pulse directly proportional to the incident photon’s energy. Comparators and counters sort the photons into energy bins based on threshold values, a process that can also filter out electronic noise and enable spectral imaging.

The semiconducting materials used in photon-counting detectors are typically either cadmium telluride (CdTe), cadmium zinc telluride (CZT) or silicon. The cadmium-based detectors have high stopping powers due to their high atomic number, leading to efficient absorption of X-rays via the photoelectric effect and resulting in a high spatial resolution. Another advantage of CZT and CdTe detectors is that the semiconductor can be relatively thin (roughly 2 mm), allowing the detector to be placed perpendicular to the direction of the incident X-rays.

Advanced spectral capabilities

Conventional CT relies on post-processing software to enhance image resolution and reduce the electronic noise that’s inherent to its physical hardware. But the algorithms traditionally used for image reconstruction – which include back projection, filtered back projection and iterative reconstruction algorithms – can reduce spatial resolution and cause blurring.

Deep learning-based reconstruction, meanwhile, can induce artefacts (such as generating objects that don’t exist or removing true small anatomical structures), particularly in low-dose scenarios where training data are limited. To achieve high resolution in conventional CT, a low-energy filter in the X-ray beam is needed, which increases the required radiation dose.

The PCCT detector design, with small pixel sizes and lack of reflective septa, make it an inherently high-resolution technique. Image quality can be further improved using algorithms such as quantum iterative reconstruction, which has been shown to reduce image noise by up to 34.5%. Sharp convolution kernels (used to optimize the balance between noise and sharpness) are needed to ensure that the image produced maintains the high resolution provided by the detector.

The ability of PCCT to distinguish photon energy also allows for material decomposition, which enables the generation of a range of advanced images. This includes virtual monoenergetic images reconstructed at a single energy level to amplify contrast agents without reducing dose, and virtual non-contrast images, which allow digital subtraction of particular materials without needing another scan. PCCT can also be used for K-edge imaging, in which contrast agents can be isolated based on their isolation of their K-edge energies.

Clinical applications

The technical advantages of PCCT have significantly improved the diagnostic applications of CT across a plethora of medical disciplines.

For instance, a prospective study on 200 adults with lung cancer who underwent both PCCT and EID CT showed that PCCT outperformed conventional CT in lung cancer management. The key findings were that PCCT had a lower effective radiation dose (1.36 mSv) compared with EID (4.04 mSv), lower exposure to iodine (a dye used to increase image contrast), with an iodine load of 20.6 mSv for PCCT (compared with 28.1 mSv for EID CT) and higher detection and diagnostic confidence for enhancement-related malignant features.

Similarly, in a study of CT pulmonary angiography, PCCT reduced the total iodine load by 26.7% and the CT dose index volume by 24.4% compared with EID CT. This potentially lowers patient risk, as well as providing environmental and financial benefits.

Within coronary imaging, PCCT enables characterization of coronary artery disease and plaque and shows promise in coronary artery calcium quantification by reducing blooming artefacts (where small, high-density structures like calcium appear larger than their true size). PCCT can also provide high-resolution imaging of the lumen for evaluation of coronary stents and assessment of myocardial tissue and perfusion.

The higher dose efficiency of PCCT makes it particularly effective in paediatric applications, as children are more radiosensitive than adults. Children also have smaller organs, making the ultrahigh resolution provided by PCCT especially helpful, for example, in the detection of tiny, complex heart defects in neonates and infants.

As of early 2025, there were two US Food and Drug Administration (FDA)-cleared PCCT systems in clinical use: the NAEOTOM Alpha from Siemens Healthineers and Samsung Healthcare’s OmniTom Elite. And just last month, the Extremity Scanner System from MARS Bioimaging and GE HealthCare’s Photonova Spectra photon-counting CT both received FDA clearance. Other clinical prototypes include systems from Canon Medical Systems and Philips Healthcare.

Ongoing challenges

As with any emerging technology, challenges remain to be solved. With photon-counting detectors, these includes effects such as pulse pile-up, charge sharing, K-escape and Compton scattering.

Pulse pile-up occurs when two or more photons arrive at the detector simultaneously, which may result in it recording this as a single photon. This leads to errors in the calculation of energy received at the detector and determination of the numbers of photons. If a single photon strikes near the boundary between two pixels it may be detected as having lower energy than it actually has. This effect, known as charge sharing, will degrade the spectral and spatial resolution of the CT image.

Due to their high atomic number, cadmium detectors are also susceptible to an effect known as “K-escape”, in which incident X-rays produce fluorescence that’s detected as a separate event. Compton scattering occurs when a secondary photon produced in the semiconductor material is registered as a separate event, underestimating the real energy value.

Finally, manufacturing the semiconductor materials used in PCCT is expensive – PCCT scanners can cost in excess of £2 million. And the large data sets generated by multi-energy scanning require a large amount of computing power and time to process and reconstruct.

Future impact

PCCT is a highly promising technology that replaces traditional indirect detection mechanisms with direct detection using semiconducting materials. PCCT offers superior image quality due to higher spatial and spectral resolution, higher dose efficiency and the ability to perform quantitative imaging. The multi-energy capabilities of PCCT shift the image from providing purely structural information to also include functional information.

Current clinical use is limited mainly due to cost rather than diagnostic capability, with a lack of clinical studies making the high cost difficult to justify. However, the potential impacts for optimizing healthcare could be vast. Perhaps it is inevitable that, as costs decrease with evolving technology, the clinical use of PCCT will overtake conventional CT in the future and become the standard CT technique.

The post Counting photons could redefine the future of CT imaging appeared first on Physics World.

In recent years the news has been dominated by devastating hurricanes, cyclones, tornadoes, wildfires and floods, and data show that these hazardous events are increasing in frequency and strength. It is clear that our weather is becoming more extreme, with a warming world adding more energy to the atmosphere and increasing the power of these wind-fuelled events.

With this in mind, Simon Winchester’s opening question in The Breath of the Gods: the History and Future of the Wind might surprise readers: are Earth’s winds slowing down? There was, indeed, a decrease in wind speeds over land between the 1980s and 2010, which was ominously dubbed the Great Stilling. In fact, observations show a decrease in average wind speeds over land of between 5 and 15% over the last 50 years. So what is going on?

Winchester – a writer and journalist with a background in geology – starts his quest to discover more atop the windiest place in the world, the summit of Mount Washington. With delicious irony, he finds the anemometers are still and a very rare calm hangs in the air.

He goes on to build the case for exceptional weather becoming the norm. He covers recent examples of extreme wind events, such as the exceedingly hot and dry Santa Ana winds of January 2025, which fed the dramatic and devastating wildfires that ripped through suburbs of Los Angeles; the record-breaking storms that pounded Europe during 2024 and 2025; and the freak tornado in March 2023 that killed 17 people and razed the town of Rolling Fork, Mississippi, to the ground.

Ever-present element

This book isn’t simply a tour of wind-related disasters, however. Winchester takes us back through thousands of years of human history, to explore how wind influenced some of the earliest civilizations. The first recorded mention of the wind arose 5000 years ago and comes from the ancient kingdom of Sumer (now south-eastern Iraq). People there identified four different prevailing winds and attributed their characteristics to four different gods. This classification system persists to this day, with our familiar north, east, south and west winds originating from these mythological four Mesopotamian winds.

For much of history humans have made use of the wind: from propelling pioneering populations in tiny boats across the Pacific Ocean some 5000 years ago, to enabling human flight; from milling grain and pumping water with windmills, to using them to generate energy. But it is only in more recent times that we have started to map and understand the major winds on our planet and the role they play in making it habitable.

Winchester romps through the science. We learn how the wind has pummelled, shaped and moulded the Earth since time immemorial, and how the winds work in tandem with the oceans, constantly transporting energy from equator to poles and preventing the planet from overheating. He also introduces key characters along the way, such as Brigadier Ralph Bagnold, a British army engineer. Bagnold used wind tunnel experiments and his extensive desert experience to understand the physics of windblown grains and the circumstances that create everything from tiny ripples in sand, to mighty marching barchan dunes.

Not quite blown away

But it is when the wind works against us that its might is truly revealed, and Winchester devotes an entire chapter to inclement winds. He starts by transporting us into the wretched five years of the American Great Depression in the 1930s, when terrible dust storms tore the topsoil from the prairie states of Oklahoma, Texas, Kansas, Colorado and Nebraska, resulting in starvation and mass migration. We hear how the arrival of the settlers and farming technology triggered this tragedy, with steel-bladed ploughs ripping through the soil and tearing up the grasses that had previously glued the soil to the land.

However, this is a tale that ends well, with President Roosevelt taking sound advice and devising an audacious plan to fix it. As a result, some 220 million trees were planted in a series of windbreaks stretching from the Canadian border down to central Texas. These restored prosperous and stable farmland to the American Midwest, and survive to this day.

Writing a book about this invisible force of nature could be stuffy, but Winchester brings his trademark curiosity and storytelling to the fore. He whisks readers through history and around the world, inserting himself into the story and pulling out the human impacts that bring the topic alive.

But while it’s a thoroughly enjoyable read, The Breath of the Gods lacks a thread to hold the book together. And most frustratingly, it fails to really return to answer the opening question about what’s behind the slowing winds. I would have liked a bit more science – particularly in understanding the impact that climate change is having on the wind – but for those looking for an accessible read with lots of fascinating weather anecdotes to regale friends with, this book won’t disappoint.

• 2025 William Collins 416pp £25hb £11.99ebook

The post Invisible force of nature: what the wind does for us appeared first on Physics World.

Most headline-grabbing advances in quantum mechanics today are experimental in nature: more qubits, entangled particles, fewer errors.

Often overlooked are the advances in the mathematics that underpins the behaviour of these quantum systems.

The walled Brauer algebra is an abstract but increasingly important mathematical structure that appears in quantum information theory whenever physicists study particles, symmetries and transformations involving permutations and partial transposition.

Work in this area inevitably leads to the question of how a system transforms when particles are permuted or when one part of a composite object is flipped (transposed) while the rest is left untouched. Collect all such operations together and you get the walled Brauer algebra. It plays an important role in the mathematical description of problems ranging from entanglement detection to advanced teleportation schemes.

The problem is that this algebra is famously intricate. Until now, physicists have only been able to describe its structure using methods that do not fully align with the natural symmetries of the system, making calculations heavy and sometimes opaque.

The new work changes that. The authors have developed an iterative construction that builds the algebra piece by piece, revealing its architecture in a symmetry-compatible way. Instead of a tangled hierarchy, the algebra unfolds into independent components, each shaped by the action of two symmetric groups.

The result is not just a more elegant mathematical picture; it is also a new framework that can make symmetry-based analysis of complex quantum-information problems more systematic and transparent.

This matters now more than ever. Quantum technologies increasingly involve many-particle configurations where symmetry is both a feature and a challenge. Teleportation schemes that move quantum information without moving particles, algorithms that manipulate unknown quantum operations, and proposals for higher-order quantum processes all rely on understanding how transformations behave under symmetry.

By clarifying this structure, the new framework could help researchers analyse these settings more effectively and support the development of better-controlled entanglement- and teleportation-based protocols.

The post The mathematics of quantum entanglement appeared first on Physics World.

This property determines whether a quantum system can outperform even the fastest classical supercomputer. Until now, scientists could quantify magic in systems of qubits, but not in systems of bosons such as photons or hybrid devices of coupled bosons and spins, like those used in real quantum hardware.

In this new work, a team of researchers from Taiwan and Japan proposed the first unified way to measure magic in systems that combine both spins and bosons. These hybrid platforms appear everywhere from superconducting circuits to trapped ion quantum processors. However the quantum resources inside them have remained difficult to identify.

The team’s new framework uses the shape of a quantum state in phase space to define a family of magic entropies that apply cleanly to qubits, bosons and crucially, the interactions between them.

To test the idea, the researchers examined the Dicke model, a paradigmatic system in which many spins couple to a single light field. As the system approaches a superradiant phase transition (a dramatic collective reorganisation), the shared non-classical behaviour across both spins and photons (the hybrid magic) peaks at this transition. This provides another way to identify the critical point, alongside familiar tools such as entanglement. Another interesting result is that, in the finite systems studied here, the quantum magic in the spin sector increases sharply, while the bosonic magic saturates to a finite value. This contrast suggests that these measures capture different aspects of the quantum state.

The team also analysed how magic evolves dynamically in the Jaynes–Cummings model, where a single spin and a single photon exchange energy. As the two systems swap excitations, magic flows back and forth, and have different behaviours for bosonic and spin parts, providing a picture of how computational power migrates through a quantum device in real time.

As quantum computers grow more complex, scientists and engineers need reliable ways to diagnose which parts of their machines produce genuine quantum advantage. This new framework gives them a powerful tool to do just that, and it’s one that works not just for qubits, but for the hybrid architectures likely to define the next generation of quantum technologies.

The post Revealing the magic in hybrid quantum systems appeared first on Physics World.

A river delta may have been present on Mars as early as 4.2 billion years ago, which is much earlier than previously thought. This is the conclusion from a new study by researchers at the University of California, Los Angeles, who have analysed ground-penetrating radar (GPR) data collected by the Mars 2020 Perseverance rover from the Jezero impact crater.

“The finding may also extend the period of flowing water and potential habitability for Jezero back further in time, says astrobiologist Emily Cardarelli, who led this research effort.

The surface of Mars carries many traces of a past watery climate, including ancient river channels, deltas, and paleolakes. Indeed, observations from space provide evidence for the existence of minerals possibly left behind as Mars’ atmosphere was gradually lost to space and its surface dried up.

Researchers are particularly interested in carbonate minerals because these preserve a record of the Red Planet’s ancient water thanks to its interactions with carbon dioxide in the Martian atmosphere at this time. How these minerals formed over the large scale in the Margin unit is unclear though.

Data collected from more than 35 metres underground

In the new work, Cardarelli and her colleagues in the Department of Earth, Planetary and Space Sciences at UCLA analysed data collected by Perseverance’s Radar Imager for Mars Subsurface Experiment (RIMFAX) instrument. They focused on a sedimentary deposit known as the Margin unit, which is rich in magnesium carbonates and lies near a fluvial inlet to the Jezero impact crater in the Nili Fossae region near Syrtis Major. The researchers already knew that this region hosts features typical of a paleolake basin and river delta deposits.

RIMFAX acquired a continuous 6.1-km ground-penetrating radar (GPR) image along the Margin unit campaign path with soundings every 10 cm and the researchers analysed 78 traverses made between September 2023 and February 2024 over 250 sols (Martian days, which are about 40 min longer than Earth days). The instrument collected data from more than 35 m underground, which is 1.75 times deeper than previous measurements at the Jezero crater.

The researchers found that the Margin unit contains a well-preserved paleolandscape with distinct river and deltaic features. These, they say, could be the remnants of a meandering river, an alluvial fan or braided river. This environment could have developed before the Jezero Western Delta viewable from orbit as early as the Noachian epoch (around 4.2 to 3.7 billion years ago).

Jezero might have hosted a habitable ancient environment

From the stratigraphic features mapped by RIMFAX, Cardarelli and colleagues conclude that the Jezero crater might have hosted an aqueous, possibly habitable environment capable of preserving biosignatures. “RIMFAX confirms that the Margin unit is distinct from a geological region known as the Upper Fan, which was deposited earlier and different in composition as well as in physical area,” says Cardarelli. “Our work suggests that there is some continuity of formation between the Margin unit and the Upper Fan, with a repeated process in Jezero crater, but at completely separate formation and deposition times.”

Indeed, a body of water might once have fed Jezero crater, she tells Physics World, and deposited sedimentary layers of varying scales, similar in size and morphology to those observed in an area known as the Western Fan. “We suggest that this was once an extensive system that included the Margin unit, although it is now a buried remnant.”

This study, which is detailed in Science Advances, highlighted only some of the specific features found since the mission began. To date, Perseverance has traversed around 40 km and has moved out of Jezero and onto the crater’s rim and the researchers say they will continue publishing their analyses from both these areas.

“I am also excited about one day returning to the Neretva Vallis region where we have detected the most compelling potential biosignatures. These may have a biological origin, but require additional study before determining if they may be evidence of past microbial life,” says Cardarelli.

The post Perseverance finds evidence for an ancient river delta on Mars appeared first on Physics World.

WE HOPE YOU ENJOYED OUR APRIL FOOL’S JOKE FOR 2026. KEN HEARTLY-WRIGHT WILL BE BACK AGAIN NEXT YEAR.

Researchers at the CERN particle-physics lab near Geneva have been left stunned after a lorry containing a vial of antiprotons went missing. The lorry had been used by the Baryon-Antibaryon Symmetry Experiment (BASE) to successfully transport 92 antiprotons around the CERN site last month.

Following their work, BASE researchers had left the lorry in the main CERN car park but found it had vanished the following morning. The antiprotons were contained in a cryogentically-cooled Penning trap composed of gold-plated cylindrical electrode stacks made from oxygen-free copper surrounded by a superconducting magnet bore.

Initial suspicion was that the lorry might have been stolen by visiting US researchers from Fermilab, but a review of CCTV footage by CERN scientist Vittoria Vetra suggests it had been left overnight with the handbrake off.

I should have paid more attention. But I was just reaching into my bag to get my baguette lunch.

CERN lorry driver Herwig Chopper

Vetra discovered that following the test run, the driver – Herwig Chopper – had hit a pine marten dashing across the car park. “I should have paid more attention,” admitted Chopper. “But I was just reaching into my bag to get my baguette lunch”.

The driver swiftly went to get help for the stricken marten, with the suspicion being that in the rush he accidently left the truck’s handbrake off.

Footage taken later in the day revealed that the antiproton lorry began moving slowly forwards towards an identical vehicle containing protons, which had been used in 2024 to successfully transport protons across the lab’s campus.

Moments later, the two trucks collided and annihilated in a brilliant flash of light that dazzled the CCTV camera.

The light was so intense that it was even picked up at CERN’s Antiproton Proton RecoIL-1 (APRIL-1) experiment, which lies just a few hundred metres away.

Initial analysis by experiment head Silvano Bentivoglio suggests that the significant centre-of-mass energy of the collision could have produced two new particles, which the team have dubbed an “angelon” and a “demon”.

This new discovery opens up a new branch of particle physics to probe the full collision spectrum of trucks containing matter and antimatter.

TV physicist Brian Cox

“This new discovery opens up a new branch of particle physics to probe the full collision spectrum of trucks containing matter and antimatter,” says TV particle physicist Brian Cox. “Who knows what we might find and it could also be possible to collide other methods of transportation to search for new forces.”

There are now calls for CERN to build the 91 km Future Truck Collider in an underground tunnel with the Vatican and other private sponsors already coming forward with significant funding.

The post Shock as CERN antiproton lorry vanishes in staff car park appeared first on Physics World.

What happens when hard science fiction collides with big-budget cinema? The latest episode of Physics World Stories delves into the ideas within Project Hail Mary – a new film about a science teacher (portrayed by Ryan Gosling) who finds himself alone on a spacecraft with the job of saving humanity from a star-dimming threat.

Host Andrew Glester talks to science-fiction author Andy Weir, whose 2021 novel inspired the production. Weir, also known for The Martian and Artemis – both adapted for the screen – has built a reputation for scientific rigour, sometimes spending days perfecting calculations for the smallest plot details. In the interview, he reflects on how his writing has evolved over time, with a growing focus on character development alongside the hardcore science.

Also in the episode is astrophysicist and science communicator Becky Smethurst, who gives her take on the film’s science. From the treatment of relativity to its refreshingly plausible take on alien life, Smethurst loves how Project Hail Mary avoids many familiar sci-fi clichés. She also shares some of her favourite recent science fiction.

Smethurst, who runs the popular YouTube channel Dr Becky, recently released a series about Project Hail Mary. It’s well worth checking out the entertaining interviews with Weir, Gosling and directors Phil Lord and Christopher Miller – all grappling with the challenge of bringing complex physics to the screen.

The post Exploring the astrophysics behind <em>Project Hail Mary</em> appeared first on Physics World.

Physicists who go into politics are a rare breed. Most famously there was Angela Merkel, who was chancellor of Germany for 16 years. Climate physicist Claudia Sheinbaum Pardo was elected Mexican president in a landslide win in 2024. Alok Sharma, meanwhile, was business secretary in the UK government and president of the COP-26 climate summit.

But Dave Robertson is even more unusual. Having originally studied physics at the University of Liverpool in the UK, he worked as a physics teacher in Birmingham for almost a decade. After spells in the trade-union movement and local politics, Robertson has been the Labour Member of Parliament (MP) for Lichfield, Burntwood and the Villages since 2024.

He’s not the only physicist currently serving as an MP. Others include Layla Moran – another former physics teacher – who’s been Liberal Democrat MP for Oxford West and Abingdon since 2017. There’s also shadow home secretary Chris Philp, who’s been Conservative MP for Croydon South since 2015.

But Robertson is the only physics-teacher-turned-MP in the current Labour government, which came to power at the 2024 general election. It won a 174-seat landslide majority, though Robertson’s own victory was wafer-thin. He squeaked home by just 810 votes over his Conservative rival Michael Fabricant, who had been Lichfield’s MP for more than 25 years.

In an interview with Physics World, Robertson admits he had little idea of what the job of MP would involve (see box). Describing the British parliament as “a truly bonkers and bizarre workplace”, he divides his time between Lichfield and London. “I try to do four days in my constituency a week and four days in parliament. That doesn’t add up, but if can split my Mondays, I can just about make it work.”

Dave Robertson MP: what happened after I got elected

Dave Robertson recalls the immediate aftermath of his victory in the UK general election on Thursday 4 July 2024.

When you win an election, they give you this envelope. I was expecting a proper, thick A4 envelope, but all they gave me was a single sheet of A4 paper folded in half. It was 4.30 in the morning, I’d had no sleep and I’d been on my feet since 7 a.m. or something stupid. And I thought “I’m not opening this now. I’m going to take it home.”

When I opened it in the morning, it basically said “Congratulations, phone this number.” So I rang and someone said “Oh, when are you coming down to parliament?” And my reaction was “I thought you’d tell me that!” In the end, I went down on the Sunday after the election and I remember walking into Westminster Hall for the first time with the person who was showing me round and she said, “So when was the last time you were in parliament?”

As I put my hand on the door, I had to admit I’d never been in the building before: it was literally the first time I’d ever been there. And it’s nothing like I expected. It is a truly bonkers and truly bizarre workplace. It’s unique and so different to everything else. That comes with its frustrations, but it is also an absolute privilege to be involved – and long may it continue.

Into the classroom

Brought up in Lichfield, Robertson began his physics degree at Liverpool in 2004. Saying he “loved every second” of his time there, Robertson particularly enjoyed nuclear physics. But it was a science-communication course, which Robertson admits he only took because he thought it would be easy marks, that made him realize how much he liked taking complicated concepts and explaining them to non-experts.

After graduating in 2007 and taking a year off, Robertson returned to the Midlands to do a teacher-training degree at the University of Birmingham. The course was largely practical, with Robertson spending most of his time getting hands-on teaching experience at various schools in Birmingham, including one – Great Barr School – that he ended up working at.

Roberston spent seven years as a physics teacher at Great Barr, which was then one of the largest secondary schools in the UK. With about 2500 pupils, it had as many as 16 classes in each year group, from age 11 to 16. Great Barr was also able to offer physics to 17 and 18 year olds who stayed on to do A-levels. “We’d always have one physics group or occasionally two in year 12.”

Rather than just focusing on the syllabus, Robertson would try to make his lessons “loud and engaging” to emphasize the excitement and sheer bizarreness of physics. Claiming he has good control of his voice, Robertson says he would also “put on accents and do silly voices” to keep pupils entertained.

He particularly enjoyed teaching a course called “Science in the news”, where pupils would look into the impact of a particular topic in the syllabus on the wider world. “That was wonderful,” Robertson recalls. “It was effectively a literature review, which let us teach a lot of the skills that we want to see kids developing when they’re learning sciences. It was fascinating.”

Not all pupils enjoyed physics. “For some kids, physics wasn’t their thing – it’s not what drove them,” he says. But he regarded it as “an absolute privilege” to teach students who were engaged with the subject, especially those who went on to study physics at university. One ex-pupil even contacted Robertson after he became an MP to say she’d just passed her PhD. “She’d dropped a note into her thesis thanking Mr Robertson for being an inspiring physics teacher.”

Political moves

Robertson’s time at Great Barr came to an end in 2016 when the school was making job cuts and he accepted voluntary redundancy. After doing supply teaching for about a year, he got wind of a post at the NASUWT teachers’ trade union, which he’d been school rep for at Great Barr. “It was one of those jobs I’d have regretted if I didn’t apply for it,” he says.

It was while working for the NASUWT that Robertson got involved in local politics. He joined the Labour Party and in 2019 was elected to Lichfield District Council, which was then run by the Conservative Party. He also stood in that year’s UK general election, but was beaten by Michael Fabricant, losing by more than 23,000 votes. “I don’t talk about that result,” Robertson jokes.

Robertson is now one of more than 400 Labour MPs and spends most of his time on local Lichfield matters. “My number one focus is very much what’s going on in my constituency, and that will always be the case,” he says. “But I’m very fortunate to be one of a very small number of parliamentarians who’ve got a science background, let alone a physics background.”

That interest saw Robertson host an exhibition in the Houses of Parliament, organized by the Institute of Physics (IOP), in June 2025 to support the International Year of Quantum Science and Technology (IYQ). “Every MP and member of the Lords would have been able to walk past and see that it was the IYQ,” he says. The exhibition was, for him, a great opportunity “to show decision-makers that the UK is one of the world leaders in quantum”.

That month Robertson also hosted a hands-on display of quantum technology for MPs and members of the House of Lords, again organized by the IOP. At the end of 2025 he sponsored another parliamentary reception, this time for physics-based companies that had won IOP Business Awards. “The event was absolutely wonderful,” says Robertson. “Seeing some of the cutting-edge science from companies on show was astonishing.”

Robertson’s focus on science extends to his membership of various cross-party parliamentary groups, including ones about nuclear energy and space. He is also chair of a new group he has set up devoted to quantum science and technology. As a backbench MP, Robertson cannot dictate or implement policy, but he says such groups “can help build up a critical mass of interest in parliament to drive an agenda forwards”.

With his background in teaching, Robertson is also keen to highlight the UK-wide shortage of physics teachers. While at Great Barr School – now rebranded as Fortis Academy – he was lucky. “I remember having a physics group meeting,” he says, “where there were six of us around the table and thinking ‘This is more [physics teachers] than most cities have’.”

As a 2025 IOP report pointed out, a quarter of state schools in England have no specialist physics teachers. In fact, more than half of physics lessons for 14–16 year olds are taught by teachers who never studied a physics-related subject beyond the age of 18. Despite some improvement, only 31% of the government’s target number of physics teachers have been recruited, while 44% of new physics teachers quit within five years.

It’s the responsibility of me and other MPs with a scientific background to spark an interest in physics

Dave Robertson MP

Robertson admits that getting the lack of physics teachers on the radar is an uphill battle. “There are 650 MPs but have they all thought about the importance of getting more physics teachers in the classroom? Probably not, if I’m honest. That’s why it’s the responsibility of me and other MPs with a scientific background to spark an interest in physics and unearth the next Paul Dirac or Isaac Newton.”

Robertson would also like to get on the influential science innovation and technology select committee to spread the message about the importance of physics. But he is wary of spending too much time in parliament with other MPs with a scientific background. “It’s more helpful if all of us have tentacles that spread out into other groups and parties and sections of parliament.”

Spreading the message

For the wider physics community, Robertson believes that physicists need to speak out more strongly about how they can tackle many of the world’s problems, notably climate change. “It’s the biggest issue at the moment and a lot of the solutions are going to come from physics,” he says. “Getting more physicists engaged with decision-makers will not only be good for the future of the economy but ultimately for the future of the planet.”

As for Robertson’s own future, he knows that a career in politics is precarious. Voters rarely hold politicians in high regard and will often boot them out on a whim. It’s therefore hard for any MP to have a predictable career path or plan too far ahead. Robertson himself admits to having “no big aspirations” to be a cabinet minister, which is perhaps just as well given that his majority at the last election was so thin.

With the next general election not due to take place until 2029, Robertson is for now focusing squarely on his role as a backbench constituency MP. “The job I have is just about the most wonderful in the world,” he says. “I want to keep doing it because there’s some wonderful things I can do for my community, whether it’s physics, quantum or football.” But if Robertson did get kicked out, at least he can go back into the classroom.

“Rumour has it, we could do with a few more physics teachers.”

• Dave Robertson also features on the 19 March 2026 episode of the Physics World Weekly podcast

The post From the blackboard to the backbenches: how physics teacher Dave Robertson became an MP appeared first on Physics World.

Physicists at ETH Zurich in Switzerland have produced magnetic fields as high as 40 T in a superconducting coil that has a bore diameter of just 3.1 mm. Until now, creating such intense fields required large and expensive facilities and tens of megawatts of power. The new miniaturized structure requires a few thousand times less power than larger magnets and it could help bring ultrastrong benchtop magnets closer to reality.

“All previous 40 T class magnets have been metres in size, weigh more than six tons, and require about 20 MW of power to operate,” says Alexander Barnes, who led the research effort. “Our miniature magnet can also generate a 40 T magnetic field, but it is small enough to fit in the palm of your hand and requires a few watts or less to operate.”

Such a device could be extremely useful for scientists who use strong magnets in their research, he adds. “Rather than having to travel to the few locations in the world that have the resources and space to house a strong magnetic field, with this technology scientists in the future could have access to these magnets in their own laboratory.”

Making the magnet tiny

Barnes and his colleagues, who are nuclear magnetic resonance (NMR) spectroscopists, came up with the idea for their new magnet by asking themselves a simple question: “what do we need to put inside it in our experiments?” The answer was: only the sample and an NMR detection coil.

“So, instead of making magnets expensive and big enough to house all different kinds of equipment, we decided to make the magnet tiny – and just big enough to be able to fit inside it what we need to fit inside it,” says Barnes. In this way, any bulky components can be placed outside the magnet and only the essential elements within the high-field region inside it.

“Think about the right-hand rule and the Biot-Savart law we all learn in first year physics,” he explains. “This law tells us the more electrons moving in a circle, the higher the magnetic field. And the more electrons moving in a circle in a smaller volume close to the sample also means a higher magnetic field. This is all we did – we tried to maximize the electrons moving in a circle near our sample.”

High-temperature superconducting tapes

Strong magnets are needed in a host of research and technology areas, from magnetic resonance imaging (MRI) and particle accelerators to NMR spectroscopy. Magnetic fields greater than 40 T can be produced using high-temperature superconducting (HTS) tapes. These structures can also be wound together to increase their already very high critical current even further, something that allows the resulting coils to reach higher magnetic fields. A famous example, Barnes reminds us, is the world-record 45.5 T steady-state magnet, which uses a HTS coil as an insert within a resistive background magnet. The problem, however, is that these high-field hybrid magnets are huge and require a lot of power.

Barnes’ team says it might now have overcome this issue with its two compact HTS magnets wound with a conducting tape coated with the superconducting ceramic REBCO. The first magnet, composed of two pancake coils, produces a magnetic field of 38 T and the second, composed of four (quad) pancake coils, a field of 42 T. The researchers say they used a specialized winding technique combined with soldering to make sure there was a jointless connection between the pancake coils at a winding diameter of 3.5 mm.

The strong magnetic fields of the coils stem from the high current-carrying ability of REBCO and the extremely small magnet bore diameter of 3.1 mm. “These magnets reach current densities of 2257 and 1880 Amm⁻² at peak currents of 1246 and 1038 A, respectively,” says Barnes, “and despite the much higher current density, they consume a few thousand times less power and require a coil volume over 1000 times smaller than that of the 45.5 T hybrid magnet.”

“Amazing” materials

He says he imagines a “bright future” where there are hundreds and thousands of benchtop magnets capable of 50 T and more, all over the world in academia and industry.  These magnets can be used for NMR and electron paramagnetic resonance (EPR) spectroscopy, but also quantum computers and other applications. For instance, the ETH Zurich team is working on a project that uses these magnets to build miniature gyrotrons, which are microwave generators. “We have plans to use such devices for spectroscopy, but also for nuclear fusion heating and even vaporizing holes deep in the Earth to extract geothermal energy,” Barnes tells Physics World.

It will not all be plain sailing, however, say the researchers. One of the main challenges in this work, which is detailed in Science Advances, is to avoid damaging the REBCO-coated tapes. These tapes are “amazing” materials, says Barnes. They are a single crystal of rare-earth barium copper oxide and are more than 100 m long, but the problem is that they are subject to mechanical strain. If this strain exceeds a certain, critical threshold, then the superconducting layer can crack, leading to reduced current-carrying capacity as the structure’s resistance increases.

The researchers say they are now busy working on increasing the magnetic fields – they are targeting 50 T soon – and performing NMR inside their existing coils. “ResonX, the commercial partner on this study, is also actively commercializing these magnets,” reveals Barnes.

The post Miniature magnets break field strength record appeared first on Physics World.

Robots tend to move things physically, using arms or other appendages. But what if robots could move objects without physically touching them? Researchers from the Max Planck Institute for Intelligent Systems, the University of Michigan and Cornell University have developed robotic swarms that can manipulate objects using only water, by inducing a fluidic torque.

Strong viscous interactions exist in microscale systems, which can be used to generate fluid flows that actuate passive objects. In their previous research, the researchers found that this manipulation can be influenced by the number of microrobots, the spin rate of microrobots and the position of the microrobots relative to the object. This latest work, published in Science Advances, has gone one step further, demonstrating that a magnetic robot swarm can assemble, transport and reorganize objects that are many times larger than the microrobots themselves.

“This study is the third in a series of papers where our team explores how microscale robot swarms can coordinate using simple global control signals,” says Kirstin Petersen of Cornell University, “Rather than controlling each robot individually, we broadcast the same signal to the entire group and rely on the robots’ interactions with each other and with their environment to produce different collective behaviours. Here, we showed that those interactions could also be used to manipulate external structures through the fluid flows generated by the swarm”.

The robots are microdisks with diameters of about 300 µm and because they are magnetic, they can be rotated using an externally applied magnetic field. When each individual microrobot spins, it drags the fluid around it, which generates a force in the liquid. While this force is small for an individual robot, combining hundreds of robots together that spin in unison (and/or increasing the spin speed of the robots) creates a much larger flow force in the water – generating a high enough torque to move objects.

“The most exciting result is that the robot collective can use the fluidic torque it generates to manipulate structures much larger than the robots themselves, without physical contact. It suggests that you could add actuation to otherwise passive objects simply by introducing microrobots in the surrounding fluid,” Petersen tells Physics World.

To demonstrate this approach, the researchers positioned the microrobots inside and outside of concentric floating ring structures, and used the number of robots, their positions and spin speeds to act as a form of control for moving objects. They found that the robots could spread out and surround the object, rotating it in the process, or they could crawl around the edges of an object, allowing them to reorganize objects. The ability to change these parameters and obtain different torques provided a tuneable and programmable way of using the microrobot swarms.

The researchers extended the principles to mechanical systems, using the microrobot to turn miniature gear trains (after turning the first gear, the other gears moved by conventional mechanical contact). They also rotated 3D floating objects that were 45,000 times the mass of an individual robot. Here, placing the robots on top of the object generated sufficient torque to rotate it, despite the mass difference.

The team also found that the microrobot swarm could dynamically assemble objects using coordinated fluid flows, in which the robots switched between their rotational function and crawling ability to move objects along a surface. This adaptive behaviour not only allowed the manipulation of objects, but also their reorganization – including expelling, dispersing and aggregating objects – based on the environment and task requirements.

The introduction of these small robots into fluids essentially turns the fluid from a passive medium into a small-scale motor. For applications where there is a risk of structural damage from mechanical manipulation, contactless manipulation could be highly beneficial. For example, this type of mechanism could be useful in microscale manufacturing and biomedical engineering, particularly for miniature device assembly, biological matter transport and targeted manipulation within the human body.

When asked about what’s next for this research, Petersen tells Physics World that “the other authors are focusing specifically on innovating microrobots, whereas my lab is studying the broader question of how collectives coordinate through their shared environment while keeping individual agents simple. We are exploring natural and engineered fluid-coupled swarms across a wide range of size scales”.

The post Magnetic microrobot swarm moves objects with water appeared first on Physics World.

A couple of months ago I wrote about whether it’s possible to teach the art of entrepreneurship or if it’s a skill that’s innate to individuals. My article led to some invaluable feedback, notably from one reader who said that, yes, of course it can be taught. Not, they said, from formal lectures but mainly through mentoring by people who’ve learned the art of entrepreneurship themselves.

That idea got me thinking about the wider benefit of “giving back” one’s experience to others who could gain from that wisdom. All professional scientists and engineers will have benefited at one time or another from the generous guidance of other people – be they teachers, lecturers, or work colleagues. So perhaps we should think about how we can do the same.

The value of a professional interaction, however small, should not be overlooked

It’s easy to imagine our lives are so inconsequential that we have nothing to teach – and even if we do have something to say, we certainly haven’t got the time to tell others about it. But the value of a professional interaction, however small, should not be overlooked. A timely moment at any career stage can make all the difference to an individual’s professional impact and future success. The scope of opportunity for giving back is broad.

Volunteering and internships

In my experience, local schools are always grateful for career guidance from professionals. Staff at my company, for example, often give career talks at their children’s schools. We take part in events such as assemblies, career evenings or careers weeks and we are currently keen to provide work experience for 16- and 17-year-olds in year 12. If we go ahead, I am sure pupils will be eager to snap opportunities up.

I have also seen the benefit of scientists and engineers developing videos, workbooks and other materials for primary-school children to learn about concepts in science and technology. It is important to make an impact at the earliest possible stage, which is where the talent pipeline starts. Once students are in their teens and have made their subject choices, it becomes hard – if not impossible – to influence them.

Internships are another great way of giving back. For the last eight years, I have been running a data-science internship programme at GE – and I just wish I’d started it sooner. Initially, we offered summer-long placements, but after a year we added year-long roles to the mix. I will be honest, colleagues were hugely sceptical about how much value these roles would bring, but their worry proved unfounded.

The vast majority of our interns have been extremely productive under our guidance and, after finishing, have gone on to secure graduate positions within GE or other tech firms. It’s vital, however, that interns are properly supported. As well as being given comprehensive induction and training, interns must be part of an established project team, whose members are always on hand to give guidance, answer questions, and provide the interns with clear tasks and goals.

It’s also important to set expectations of professionalism when at work. We are fortunate in GE that interns are taken on as regular employees and so have access to a wide range of employee and company benefits. Interns therefore find it easier to feel part of the company and adopt its ethos. Remember too, that the benefits work both ways. Interns bring you new perspectives and fresh ideas, while also keeping the rest of the team stimulated.

Professional societies and professorships

Being a member of a professional body is also a great way to give back to the community. The Institute of Physics (IOP), for example, has an active volunteer community, along with special interest groups and regional and national branches that are all run by member volunteers, with help from IOP staff. Becoming an IOP volunteer also gives you the chance to influence and help shape the physics community.

By meeting like-minded colleagues, you can build your network and give back to the community at the same time

You could, for example, get involved with running lectures, seminars, webinars and career outreach events. By meeting like-minded colleagues, you can build your network and give back to the community at the same time. There are some great examples, notably Deborah Phelps, a physicist in engineering who ended up launching the IOP’s girl-guiding badge.

For more experienced industrialists, another way to give back is to become a visiting professor. Being fortunate enough to hold such a position myself, they let you go back to university and share your knowledge and experience with current students. It’s invaluable for universities too, allowing students to learn what real-life careers look like and what skills they might need beyond the technical knowledge gained during a degree.

Visiting professorships tend to be awarded directly by universities. But competitive awards exist too. The Royal Academy of Engineering, for example, runs a scheme that brings engineers, entrepreneurs, consultants and other industry insiders into UK universities to boost undergraduate engineering education. Covering areas that would appeal to physicists, such as energy, materials and electronics, the scheme lets experts deliver face-to-face teaching, mentoring and curriculum development for three years.

The Royal Society, meanwhile, runs an entrepreneur-in-residence scheme that’s been taken up by people like Fiona Riddich, who originally studied maths and physics before joining the energy industry. She’s mentored students at the University of Edinburgh and developed a project called Energy@Edinburgh to raise awareness of researchers’ work, promote interdisciplinary exchange, grow staff understanding of the energy market, and encourage innovation and translation of research.

I have only scratched the surface of what can be done for the good of our scientific and engineering community, but there is plenty of opportunity and few, if any, barriers to entry. I can’t emphasize enough the importance of doing this, especially for growing our pipeline of technical breakthroughs and developing talented people for the future.

My challenge to you is to tell your colleagues what you’re already doing to “give back” – and why. And if you’re doing nothing to give back, now is the perfect time to get started.

The post Why mentorship is vital for the future of physics appeared first on Physics World.

The amount of moisture in soil – and the way this moisture is distributed – combined with wind patterns in the lowest few kilometres of the atmosphere can influence where thunderstorms begin and how they develop. This new finding, from researchers at the UK Centre for Ecology and Hydrology (UKCEH) could help in the development of new early warning systems for such events, which are increasing worldwide and becoming more intense and dangerous as the climate warms.

Thunderstorms can develop quickly on hot afternoons, sometimes in less than half an hour of clouds building up, but predicting where they originate can be difficult.

A team of researchers led by meteorologist Christopher Taylor has now discovered that patches of dry soil 10–50 km across can combine with the wind field and affect how quickly convective storm clouds (cumulonimbus) form and grow.

“We already knew that differences in wind speed and direction with height (the ‘vertical wind shear’) in the atmosphere are critical ingredients for severe storm development, whilst gradients in land surface heating across the landscape can induce weak winds near the ground,” explains Taylor. “These two elements are usually studied separately, but we put them together and found that convective clouds grow very rapidly when the winds that steer them, some 3–4 km above the ground, oppose local surface-generated winds near the ground.”

This combination, he says, effectively increases the supply of moist, buoyant air into a cloud, accelerating the updraughts responsible for lightning and heavy rain.

“Storm initiations are clearly favoured in specific locations”

The result, he explains, challenges conventional thinking that over flat terrain, where cumulonimbus first develop, is essentially random. “In fact, under the conditions we studied – across sub-Saharan Africa – storm initiations are clearly favoured in specific locations, based on a combination of soil and wind conditions on that day.”

The work, which is detailed in Nature, could help in the development of more localized storm forecasting, he says, particularly in tropical areas where soil moisture gradients and wind shear are strong and can lead to flash flooding, lightning and strong winds.

The UKCEH team obtained its result by studying satellite images of 2.2 million afternoon storms in 2004–2024. They were able to obtain high-resolution data from the images and so observe fine-scale details of the wetness of soils.

The principle they have identified would be applicable to predicting thunderstorm formation in other parts of the world, such as Asia, the Americas, Australia and Europe – and not just the worst-hit tropical regions in Africa.

Ground-based measurement networks are scarce in Africa

Taylor and colleagues say they have been working with meteorological services in Africa for the last few years and contributing to international efforts to provide early warning systems for severe storms. Convective storms can be particularly damaging in built-up urban areas with intense rainfall damaging infrastructures such as roads and sanitation systems. “Unlike in the UK, where ground-based measurement networks are the backbone of weather forecasting, they are scarce in Africa and there are only a handful of meteorological radars here, explains Taylor. “We therefore had to rely on satellite data, which provide good quality information on some aspects of the coupled land-atmosphere system – notably the temperature (and therefore the height) of clouds and estimates of moisture in the top few centimetres of the soil.”

From this information, the researchers inferred how soil moisture affects evapotranspiration and atmospheric heating, how pressure gradients created by these heating patterns affect winds locally and, finally, how these inferred local winds interact with growing convective clouds.

The insights gleaned from this study could help improve the accuracy of short-term weather forecasts by providing a better indication of where storms are likely to appear within a region, Taylor says. “Just how much more skilful a forecast will be is an open question, but we have good reason to believe that in parts of Africa it could provide a big advance. In general, weather forecasting is a rapidly evolving field thanks to AI, and so the translation from research finding to application could be rapid.”

The researchers say they are now starting to look at how weather forecast models depict the processes described in their work. “Early indications suggest that models solving physical equations on a fine enough grid (of around 4 km) can capture the relationships between soil moisture, wind shear and cloud growth, but operational weather forecast models will require more accurate information on spatial variations of soil moisture to produce better forecasts,” says Taylor.

“We are also looking at how predictive models based on deep learning can exploit the new knowledge to provide forecasters with early indications of where storms may appear later in the day,” he reveals.

The post Where do thunderstorms form? appeared first on Physics World.