Over the past two decades, photonic-crystal surface-emitting lasers (PCSELs) have shown promise as a type of advanced semiconductor laser useful in defense- and aerospace-related applications. Typically, these devices are made with photonic crystal patterns that repeat across the area of the device. But new research from the lab of electrical and computer engineering professor Kent Choquette has demonstrated a quasi-periodic photonic-crystal surface-emitting laser (QPCSEL). Fabricated with their buried dielectric platform, the group's device highlights a new avenue for creating tunable, more reliable semiconductor lasers. Their findings appear in Applied Physics Letters.
Researchers at the University of Basel and the Technical University of Munich have developed a new method to reveal the collective motion of electrons in one of the most elusive states of matter: the Wigner crystal. Using light, the physicists were able to uncover previously inaccessible properties of this fragile quantum state.
Researchers at the University of Basel and the Technical University of Munich have developed a new method to reveal the collective motion of electrons in one of the most elusive states of matter: the Wigner crystal. Using light, the physicists were able to uncover previously inaccessible properties of this fragile quantum state.
A radio signal has been amplified by scattering it from a stationary coin-sized electronic circuit that behaves as though it is rotating at an enormous rate. Conceived by a team at the City University of New York, the experiment is said to provide the first observation of rotational super-radiance involving electromagnetic waves. This wave-amplification effect is inspired by rotating black holes and was predicted more than half a century ago. Andrea Alù and colleagues found that only radio waves carrying a particular kind of twist were boosted, by as much as a factor of six in power.
In 1969 Roger Penrose pointed out that a rotating black hole holds a vast reservoir of energy that, in principle, can be tapped. “An object entering the region around the black hole can split into two parts, one falls into the black hole while the other escapes with more energy than the original object had, effectively taking some rotational energy from the black hole,” Alù, explains.
Two years later the Soviet physicist Yakov Zel’dovich realized that the same thing should happen to waves. “If a wave carrying angular momentum reflects from a rapidly rotating absorbing cylinder, the reflected wave could be amplified and come back stronger than it arrived,” says Alù. That amplification is called rotational super-radiance, which Alù describes as, “a process in which a wave becomes stronger by extracting energy from a system that rotates very rapidly”.
The catch has always been the word “rapidly”. For the effect to occur, the rotation must outrun the wave itself, and for light or radio waves that means rotational rates no mechanical object could survive. The effect has been coaxed out of water waves swirling around a vortex and out of sound waves bouncing off a spinning absorber, but electromagnetic waves had been out of reach. “While the idea is fascinating, no experimental demonstration was reported for electromagnetic waves, due to the required very fast speeds,” Alù says.
Clever solution
The CUNY team has found a clever way around the speed restriction. “Instead of physically spinning an object, we created an artificial rotation by periodically changing the properties of a network of resonators in space and time in a way that mimics rotation,” says Alù. The new device is disarmingly simple, comprising three small electrical circuits wired into a loop roughly two centimetres across, each one tuneable like a radio dial. The tuning of all three is wobbled up and down, with each kept slightly out of step with its neighbours, so the pattern sweeps around the loop like a wave passing through a stadium crowd.
“Although no physical object is rotating, this travelling modulation pattern acts like a rotating system,” Alù explains. And because the apparent speed is set purely by how quickly the electronics are driven, it can be pushed as high as one likes. “In fact, this speed can be faster than the velocity of light without violating any physical law.” Nothing material moves, so nothing outruns light.
The researchers fed a 100 MHz radio signal into the loop. This light was in a specific twisted state (possessing orbital angular momentum). They then swept the rotational rate from 5 MHz up to 195 MHz. Below 100 MHz the reflected light weakened steadily, as expected. Above 100 MHz, however, the synthetic rotation overtook the wave and the behaviour flipped. The reflected signals reappeared at the same frequencies as before — 60, 70 and 80 MHz — but were twisted the opposite way, and were stronger rather than weaker. That reversal, Alù notes, is “a key signature of entering the regime associated with super-radiance”. The gain arises in special windows the team calls angular-momentum bandgaps, which open once the synthetic rotation is fast enough and through which “energy can be transferred from the synthetic rotation to the wave”.
Fussy amplfier
The amplification was fussy about its input. “Our observed amplification was selective to the angular momentum of the input wave, only waves with particular angular-momentum properties experienced gain,” says Alù. Stranger still, the effect feeds on waste. In an ordinary amplifier, energy leaking out of the device is the enemy. Here a leakier circuit gave more gain, exactly as the thermodynamic reasoning behind super-radiance demands.
Alù is careful about what the experiment does and does not deliver. “The experiment does not study actual black holes or quantum gravity. Instead, it creates a laboratory system that reproduces some of the same physical principles involved in rotational energy extraction.” What it offers, he says, is “a controllable analogue platform where researchers can test and explore concepts that are otherwise difficult or impossible to study experimentally in astrophysical black holes”.
Three circuits in the loop allow only three distinct twists, so the immediate goal is bigger loops supporting a wider range. Beyond that lies the jump from radio waves to visible light, and a quantum version in which synthetic rotation might conjure photons out of empty space. Practical spin-offs may arrive sooner. Amplifying only one twist at a time is a natural fit for encoding information, and, Alù suggests, “new forms of lasers, with selective emission of angular momentum, can be envisioned”.
In a new Nature Physics study, researchers accelerated electrons to more than twice the energy predicted by the traditional dephasing limit for laser-plasma accelerators operating over the same distance. This was made possible by a specially engineered laser pulse called a flying focus, which counteracts a longstanding limitation known as "dephasing."
In a new Nature Physics study, researchers accelerated electrons to more than twice the energy predicted by the traditional dephasing limit for laser-plasma accelerators operating over the same distance. This was made possible by a specially engineered laser pulse called a flying focus, which counteracts a longstanding limitation known as "dephasing."
Using light to process quantum information is one of the most promising approaches to building future quantum computers. Light particles, known as photons, are excellent carriers of quantum information, but their lack of natural interactions has created a major challenge for researchers seeking to build systems capable of performing a full range of computations.
Using light to process quantum information is one of the most promising approaches to building future quantum computers. Light particles, known as photons, are excellent carriers of quantum information, but their lack of natural interactions has created a major challenge for researchers seeking to build systems capable of performing a full range of computations.
Researchers achieved the first real-world demonstration of quantum entanglement over a busy telecommunications fiber network. A single photon carrying quantum information had to travel more than 24 kilometers through an optical fiber already crowded with powerful internet signals. Despite the noise, it reached downtown Chicago still entangled with its partner at Northwestern University’s Evanston campus. [...]
A few years ago, I was lucky enough to see the Bayeux Tapestry – the famous embroidered cloth depicting the Norman invasion of England in 1066. More than 900 years old, this historic piece of art is only 50 cm wide but more than 68 m long. It’s also extremely fragile, which why I was astonished when I heard that the Bayeux Tapestry was going to leave its home in Normandy and be transported across the English Channel to the UK.
I’m fascinated by how non-invasive optical techniques have been crucial in advancing our understanding of the tapestry
So what’s all this got to with physics? Well, I’m fascinated by how physics – and specifically, non-invasive optical techniques – have been crucial in advancing our understanding of the tapestry and its historical significance. Thanks to physics-based equipment developed by hi-tech manufacturers, we’ve learned about how the Bayeux Tapestry was initially made, what damage it subsequently suffered, how it was repaired, and the nature of its current condition.
Such information is vital not only for increasing our historical awareness, but also for current conservators who want to understand the tapestry’s underlying condition and find out how to preserve it for future generations. And before the pedants write in, yes I know that while it’s known as the Bayeux Tapestry, technically it’s an embroidery. That means it was created by stitching woollen threads onto a linen backing, which is helpful to know when reviewing the physics involved.
Optical sleuthing
The beauty of using optical methods to study the Bayeux Tapestry is that they are non-destructive and non-intrusive – and so can typically be applied in situ. In 2017 a three-year project was started, in which conservationists used high-resolution 2D imaging, photogrammetry, multimodal scanning and advanced image reconstruction techniques to determine the tapestry’s condition and conservation needs. The project revealed considerable information about how this artwork was created and modified over time.
Thanks to these high-resolution images, we now have a single digital map of the entire tapestry, making it possible to zoom in and look at individual threads. It’s yielded information such as the width of stitches and the positions where the wool threads cross the original linen background. As a result, historians now believe the tapestry was made by a single group of embroiderers, who – knowing the skills that existed at the time – were probably based in Canterbury, UK.
Techniques such as infrared spectroscopy and fluorescent and reflection ultraviolet imaging have revealed information about what’s underneath the surface of the tapestry
From the size and direction of the stitches, we also think the outlines of the figures were stitched first, with the shapes filled in afterwards using coloured wools in a strict, specific order. Meanwhile, techniques such as infrared spectroscopy and fluorescent and reflection ultraviolet imaging have revealed information about what’s underneath the surface of the tapestry. In particular, they’ve located the presence of stains such as glue, wax (dripped from candles that lit the tapestry) and even oil from the hands of people who touched it.
Infrared light passing through the dark-coloured wools have also revealed original sketch lines that were drawn on the linen base before the wool stitching started. It reveals the original artist’s draft, likely to be someone familiar with manuscript drawing – perhaps an illuminator of religious books.
Researchers in France, led by Stéphane Le Mouélic from Nantes University, who originally did a PhD in astrophysics, have also used computer software to combine more than 440 overlapping 2D photos taken from multiple angles to create a detailed 3D model of the Bayeux Tapestry (J. Cult. Heritage71 211).
It digitally “irons out” all the sags and wrinkles in the line fabric, recreating the original, “flat” tapestry and allowing the original physical shape of the artwork to be revealed for the first time. The 3D model can be viewed for free at the Bayeux Museum website, allowing historians, researchers and members of the public to study it without having to handle the delicate material.
Physics-based techniques have also allowed us to deal with the fact that parts of the fabric have been repaired over the last 900 plus years. Some of those repairs used non-authentic dyes and colours, while others covered up the original stitching. But using computer vision and image processing, threads that were added later can be subtracted digitally, providing a clearer, corrected view of what the original tapestry looked like.
Finally, optical tools can help keep the tapestry safe for future generations. Museum curators need to know if the cloth is sagging, tearing, or changing shape over time. Instead of putting heavy tools on the cloth, lasers can scan the cloth to accurately map of the contours of its surface. By repeating this exercise every few years, conservationists can spot if any part of the cloth has stretched or sagged, enabling minor problems to be rectified before they end up causing significant damage.
Without the huge amount of investigative and restorative work carried out, the Bayeux Tapestry would never have been allowed to make the journey to London
In 2025 Le Monde newspaper reported that experts had, over the previous five years, meticulously documented 24,204 stains, 9646 holes and 30 tears in the artwork. Without the huge amount of investigative and restorative work carried out, the Bayeux Tapestry would never have been allowed to make this year’s journey to London. Advanced and detailed optical measurement has “de-risked” the tapestry’s trip.
A new type of “photonic multi-lane highway” that can carry multiple topologically-protected optical signals at once – without the need for a bulky insulator – has been demonstrated by researchers in China. The technology, which relies on a new type of material called a photonic valley half-semimetal to achieve topological protection, is currently at the prototype stage. However, the researchers believe that, if fabrication challenges can be addressed, the combination of spatial efficiency and topological robustness could be promising for future photonic technologies.
In the past 20 years, photonic topological insulators have become widespread for connections in devices such as on-chip photonic circuits because their edge modes can only conduct light in one direction and are therefore are inherently immune from scattering off imperfections. However, the protected edge mode of a topological insulator comes at a cost: the bulk must have an optical band gap, which means it must be opaque to the relevant frequency. Meanwhile, the photonic analogue of another concept from electronics has also become popular in optical waveguides. Gapless photonic semimetals – analogous to graphene – can be placed between topologically distinct optical insulators to broaden the guided modes, but non-guiding insulating claddings are still required.
To address the fundamental trade-off between spatial efficiency and topological protection in conventional topological waveguides, researchers in the group of Che Ting Chan at the Hong Kong University of Science and Technology in China and their collaborators introduced a novel photonic structure called a photonic valley half-semimetal. Here, the valley degree of freedom refers to inequivalent local energy extrema in momentum space, which can be used as independent degrees of freedom for transport. Crucially, a single photonic valley half-semimetal plays a dual role via its two valley channels: one valley acts as a gapless semimetal that enables waveguiding, while the other functions as a topological insulator that provides a topological barrier for the corresponding valley mode in adjacent regions.
Four stacked layers
The researchers designed a waveguide comprising four stacked layers of a honeycomb structure made from interconnected rods of the magnetic material yttrium iron garnet, which interfered with the propagating photons. By altering the diameters of the rods or the magnetic field, the researchers constructed four inequivalent photonic valley half-semimetal domains and arranged them in a specific periodic sequence. This creates adjacent domains that mutually insulate each other.
Xiaohan Cui is lead author on a paper in Nature that describes the research. She explains that the underlying topological physics is similar to that in a traditional photonic topological insulator.
“The important difference lies in how the mode is spatially implemented,” she says, “In a conventional photonic topological-insulator waveguide, two gapped bulk domains meet at an interface, and the propagating mode is tightly localized to that interface. Most of the surrounding insulating material remains inert, serving only as cladding.”
In the present configuration, however, the researchers were able to use the blocked valley as topological protection for unidirectional propagation in the neighbouring domain, and utilize this to create a four-lane highway, with two lanes in each direction, that could guide signals around sharp bends and through constrictions without backscattering or inter-lane crosstalk:
No wasted space
“The architecture transforms the usual narrow interface state into a set of directly adjacent, large-area waveguiding lanes. Consequently, no region of the device is ‘wasted’ as inert cladding,” explains Cui.
The team’s current device works for microwave radiation but the team says that the design could be adapted and extended to operate at higher frequencies.
“The present experiment is a proof of principle demonstration at microwave frequencies, so one clear next step is to move the concept towards higher-frequency, chip-scale integrated photonics platforms, thereby paving the way toward ultra-compact topological photonic circuitry,” says Cui.
The researchers believe application in the terahertz regime should be possible using magnetized semiconductors such as indium antimonide. However, non-reciprocal applications at higher frequencies could be challenging owing to the weakness of magnetic effects.
“The major experimental challenges will be to realize these higher-frequency designs while managing geometric complexity, fabrication tolerances, and propagation loss, and ensuring efficient coupling with practical sources, detectors and other photonic components,” she explains.
Quantum optician Mahmoud Jalali Mehrabad of Massachusetts Institute of Technology believes the work brings an important issue into focus. “A paper doesn’t always have to have the perfect solution as long as it highlights and really streamlines a key problem…To me this paper does that,” he says. “Spatial efficiency has been a problem in topological physics and the question is why? Is there any other way to destroy this trade-off? It shouldn’t be a side problem in the supplementary material of a paper – this is a big problem.” Whether or not the researchers can make their own solution viable, he says, “time will tell”.
When Ryan Hamerly was a 15-year-old at Boulder High School in Colorado, he spent his summer building a Tesla coil after seeing a classroom demonstration. “I thought that was really, really cool,” he recalls. “I wanted to make one myself, and as a result I ended up studying the theory of electricity and magnetism over one summer.”
In hindsight, Hamerly realizes he didn’t use much theory to construct the coil, which became part of a school physics project. “Most of the design was based on things I had read on the Internet,” he explains, “but I did try to teach myself electricity and magnetism – and it did work in the end.”
In 2006 Hamerly’s interest in physics took him to the California Institute of Technology (Caltech) for his undergraduate studies. Keen to do graduate research, Hamerly was most fascinated by fundamental theoretical problems in quantum field theory, such as dark matter and quantum gravity. But as he started toying between different options, he had a chance encounter with Hideo Mabuchi, an applied physicist at Stanford University.
“One thing that Hideo told me that I thought was particularly fascinating,” says Hamerly, “is that quantum field theory is just a generic tool that applies in many other fields.” He therefore ended up doing a PhD in optical and quantum computing under Mabuchi’s supervision, which he completed in 2016.
Hamerly then moved to Japan, where he studied at the National Institute of Informatics in Tokyo – a time he characterizes as “sort of a postdoc, but more an excuse to travel for a year”. He did, though, get a paper out of it “so it wasn’t wasted”. In Tokyo, Hamerly worked with Mabuchi’s longtime friend Yoshihisa Yamamoto – a quantum optics researcher who had previously led a group at Japanese telecoms giant NTT for over two decades.
Step into industry
When Hamerly returned to the US in 2017, he did a formal postdoc under quantum photonics engineer Dirk Englund at the Massachusetts Institute of Technology (MIT). And in a fortuitous turn of events, Yamamoto also came to the US to establish the Silicon Valley start-up NTT Research, with the intention of forming collaborations with US universities.
“[Yamamoto] just called me up and said they had a position at NTT to work in optical computing,” he says. “At the time it made most sense to stay at MIT working as a collaborator [rather than relocate to the NTT campus] because that was where a lot of our experiments were being done.”
Today, Hamerly is a senior research scientist at NTT Research’s Physics and Informatics (PHI) Lab in Sunnyvale, California. He divides his time between MIT – where his collaboration with Englund continues – and the PHI laboratory, about 15 km from Stanford. He works at the intersection of optics, deep learning and quantum computation. For example, one of Hamerly’s projects looks into ways to reduce the energy consumption of AI data centres using optical interconnects in place of electronic ones.
Researchers hope it might one day be possible to design processors that perform calculations using optical logic that are either impossible, or at least energetically unfeasible, using electronic logic. To this end, in January 2026 Hamerly co-founded Opticore – a company producing photonic integrated circuits for energy-efficient, high-speed AI – with UC Berkeley professors Mengjie Yu and Zaijun Chen, who was previously a postdoc in Englund’s MIT group.
Different setting, same science
Hamerly does not view his place at NTT Research as purely an industry position. “The mission at NTT Research is about generating ideas that will ultimately have some use in industry,” he explains, “but the fundamental focus is on those ideas and on the research.”
The mission at NTT Research is about generating ideas that will ultimately have some use in industry
His experience at NTT Research has shown him that an industrial lab can be smaller and more focused than one at a university – but that can be a double-edged sword. “[At a university] it’s nice to be able to go into seminar rooms and see a talk from a travelling world expert in a different field,” he says, “but on the other hand, the average person [at NTT] tends to be a lot more experienced and productive than say a graduate student in academia who is still learning.”
Starting out Ryan Hamerly recently helped launch photonic processor start-up Opticore alongside his academic collaborators. (Courtesy: NTT Research, Inc)
However, the chance to meet and interact with scientists from different areas is still the same. “Science is science, regardless of what institution you’re affiliated with,” he says. “We’re still doing the same things: we do research in a lab, we write up the results, submit them and publish them in journals, and we go to conferences and present our work.”
Hamerly still sees himself as principally a theorist. He spends much of his time writing computer code – occasionally for models that run on a supercomputer but usually for models that can run on his laptop. The rest of his time is focused on writing papers, travelling to present work, responding to reviews or in meetings.
Looking to the future, Hamerly believes that technology will impact research, but that the core elements of a researcher’s role are likely to remain similar for the foreseeable future. “The job of a researcher before the Internet, for example, is not too different from a post-Internet researcher,” he says, pointing to how you still have to communicate research via papers and conferences, and understand the field by reading others’ publications.
“There will definitely be changes in the way you do every one of these things in the next 10 years, especially with AI, but I don’t see any of them becoming optional.”
For young researchers entering the field, Hamerly advises keeping your options open. He did not envisage himself leaving full-time academia and work in an industrial lab, but switched because it offered a better opportunity to pursue the research he wanted to do. “They are both good routes to do research,” he concludes, “but you might find – based on which offers you get – that one is better than another.”
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.
“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.
Quantum materials could transform technologies ranging from powerful computers and highly secure communications to advanced energy systems, but one major obstacle has long stood in the way. Most quantum materials reveal their unusual properties only when chilled to temperatures near absolute zero. At room temperature, continual atomic vibrations caused by heat can overpower the fragile [...]
A new study is turning an elegant quantum idea into a practical platform for light. In research published in Light: Science & Applications, physicists report “topological Jackiw–Rebbi” states engineered inside photonic van der Waals heterostructures—systems built by stacking atomically thin materials with precisely tailored interfaces. The result is a photonic phenomenon that echoes how particles can be trapped at boundaries where the rules of their governing equations change.
The work builds on the classic Jackiw–Rebbi mechanism, originally proposed for relativistic particles. In those models, a localized mode appears when a mass term flips sign, effectively creating a domain wall. The authors translate this concept into optics by designing photonic structures where an effective “mass” characterizing light propagation changes across an interface.
What makes the platform especially compelling is the van der Waals architecture. Unlike conventional fabrication routes that can introduce disorder, the layered nature of these materials enables sharp, controllable boundaries and tunable photonic band structures. By adjusting the stacking and interlayer optical responses, the researchers create conditions in which topological modes become robust against typical imperfections.
The study emphasizes that these states are not merely conventional guided resonances. Instead, they are tied to topology: the light modes are associated with an invariant property of the band structure. As a consequence, the Jackiw–Rebbi-like photonic states are expected to persist even when the system’s details vary, so long as the relevant symmetry and band configuration remain intact.
Topological protection is more than a slogan. In photonics, it can translate into reduced sensitivity to fabrication tolerances and a pathway toward devices that rely on stable boundary transport. The paper therefore positions these localized states as building blocks for future optical components that route signals along designed interfaces.
The authors demonstrate the concept theoretically and connect it to experimental observables by focusing on how the interface should host modes localized near the domain wall region. Such localization is a hallmark of the Jackiw–Rebbi scenario, now realized in a controllable, designer photonic environment.
Beyond fundamental interest, the approach could influence the design of reconfigurable photonic circuits. Because van der Waals stacks can be combined and adjusted, the same topology-driven logic may be extended to new material systems, wavelengths, and device geometries.
Overall, the report signals a broader trend: using topological field-theory ideas to engineer light–matter behavior in atomically precise platforms, potentially enabling the next generation of robust, interface-based photonic technologies.
Subject of Research: Topological photonic states (Jackiw–Rebbi) in van der Waals heterostructures.
Article Title: Topological Jackiw-Rebbi states in photonic Van der Waals heterostructures.
A technology has been developed that allows artificial intelligence to inversely determine the process conditions for quantum-dot light-emitting diode (QLED) devices—conditions that previously required extensive trial and error to identify.
Seoul National University College of Engineering announced that a joint research team led by Professor Namkyoo Park and Professor Sunkyu Yu of the Department of Electrical and Computer Engineering at SNU, in collaboration with Professor Xianji Piao of the School of Electrical and Computer Engineering at the University of Seoul, has developed a photonic integrated circuit that can slow light on demand.
Researchers have shown that it's possible to take clear, high-resolution X-ray images using very little radiation. With more development, the new approach could eventually make medical X-ray diagnostics less risky and more accessible.
Quantum technologies, which leverage the principles of quantum mechanics, have been found to outperform their classical counterparts on specific tasks. Among other things, past studies have highlighted the potential of quantum systems that can enable long-distance communication, using photons (i.e., particles of light) to carry quantum information.
In a groundbreaking stride toward the future of quantum technology, researchers have unlocked a new mechanism to control quantum emitters embedded in hexagonal boron nitride (hBN), a layered two-dimensional material. This breakthrough could serve as a critical leap forward in integrating quantum emitters into practical devices, bringing quantum computing, secure quantum communications, and ultra-sensitive quantum sensors closer to reality. This promising development emerged from meticulous experimental studies demonstrating the ability to reversibly tune the color and wavelength of light emitted by quantum defects in hBN simply by twisting its atomic layers.
Quantum emitters are nanoscopic sources of light that emit photons with quantum characteristics, pivotal for next-generation technologies reliant on quantum information processing. However, a formidable challenge in utilizing these emitters has been the difficulty in precisely controlling their optical properties post-fabrication. Dr. Angus Gale, the lead scientist behind this research, elucidated how their work provides an innovative “lever” by exploiting the intrinsic layered nature of hBN to adjust the quantum emission properties dynamically. Unlike traditional solid-state hosts such as diamond or silicon carbide, whose structures are rigid and three-dimensional, hBN’s atomically thin layers can be mechanically manipulated, lending itself to an unprecedented degree of tunability.
The team’s experiments demonstrated that by picking up, stacking, twisting, and restacking these ultra-thin hBN slices at varied angles, they could modulate the quantum emitters’ light emission dramatically. These shifts in wavelength were not minor perturbations but substantial changes far exceeding what has been typically achievable in similar solid-state quantum systems. This finding challenges the traditional paradigm which often seeks to stabilize quantum defect behavior within rigid host materials. Instead, the researchers embraced the inherent flexibility and twistability of hBN to realize a new class of quantum control.
Professor Igor Aharonovich, the supervising author, emphasized the broader implications of this twist-controlled modulation approach. He noted that coupling two-dimensional materials at specific twist angles opens up an entirely fresh set of physical phenomena that were previously inaccessible. By assembling layers with precision angular misalignment, new quantum states can emerge, potentially transforming the landscape of material engineering for quantum applications. This strategic layering and twisting, known as “twistronics,” has already inspired revolutionary advances in graphene-based systems, yet this study extends the concept into the realm of quantum emitters embedded in hBN.
One key advantage of using hBN is that its layered crystal structure allows researchers to systematically alter the interaction between layers, effectively tuning the electronic environment surrounding the defects responsible for quantum light emission. As Dr. Gale metaphorically illustrated, far from being a solid block, hBN behaves more like a stack of cheese slices. Just as peeling and recombining slices of cheese can change how flavors intermingle, twisting hBN slices changes the interaction between atomic planes, which in turn alters quantum emitter characteristics. This mechanical engineering at the nanoscale provides a versatile platform for on-demand tuning of quantum light sources.
This technology breakthrough is fundamentally experimental but holds widespread implications. Adjustable quantum emitters could accelerate the development of quantum computing hardware, where precise photon control is essential for encoding and manipulating qubits. Similarly, secure quantum communication protocols rely on tailored quantum light sources to guarantee the generation and distribution of entangled photons immune to interception. Moreover, quantum sensing that exploits the extreme sensitivity of quantum states to environmental changes stands to benefit significantly from tunable quantum emitters, pushing the boundaries of detection limits in fields ranging from medicine to navigation.
Another remarkable facet of the research is the ability to repeatedly pick up, twist, and restack hBN layers without degrading the quantum emitter properties. This reversibility enables iterative fine-tuning of device characteristics and might yield adaptable quantum systems reconfigurable post-production, a feature highly desirable from a technological deployment perspective. This contrasts sharply with permanent structural modifications used in conventional quantum emitter fabrication, which restrict adjustable control and device flexibility.
The team’s methodology involved sophisticated nanofabrication techniques and high-resolution optical spectroscopy to probe the quantum emitters’ response to twist-induced modifications. By correlating the angular misalignment with spectral shifts in emitted light, they constructed a detailed understanding of the underlying physics governing emission control. These insights provide a blueprint for engineering tailored quantum emitters with bespoke characteristics suitable for specific applications.
The research findings have been detailed in a paper published in the eminent journal Science Advances, signaling the scientific community’s enthusiasm for the potential unlocked by twistable quantum systems. Importantly, the authors have declared no competing interests, affirming the independent and foundational nature of this inquiry. Funded by the Australian Research Council and the Air Force Office of Scientific Research, the work highlights the vibrant collaboration between academic institutions and funding bodies committed to propelling quantum technologies.
This discovery heralds a new era in quantum material science, where layered two-dimensional crystals are no longer passive hosts but active tunable platforms. By harnessing the mechanical and electronic versatility of materials like hBN, researchers are gradually unlocking complex quantum phenomena with precision control previously deemed unachievable. The implications extend well beyond fundamental research, marking exciting progress toward quantum devices that could redefine computational power, information security, and sensory precision globally.
In summary, the twist-controlled modulation of quantum emitters in hexagonal boron nitride exemplifies the convergence of cutting-edge experimental physics and materials science innovation. By capitalizing on the unique layered architecture of hBN and the emerging discipline of twistronics, this research pioneers functional tunability in quantum light sources. As the scientific community continues to develop and refine these approaches, we edge closer to the practical implementation of quantum technologies that promise profound societal and technological transformation.
Subject of Research: Not applicable
Article Title: Twist-controlled modulation of quantum emitters in hexagonal boron nitride
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