The material at the heart of the study is a modified form of strontium titanate, a single crystal with a genuinely unusual combination of properties. Strontium titanate is a metal in the sense that electrons can move through it, yet it also hosts tiny regions within its lattice that behave like microscopic magnets for charge, each with a distinct positive and negative side. These entities, known as polar nanoregions, are vanishingly small structures embedded in the crystal, and each one can point in a different direction or, under the right conditions, line up with its neighbors into an organized pattern. When they align, the material becomes ferroelectric, meaning it possesses a spontaneous electric polarization that can in principle be switched. Understanding what triggers that alignment is central to explaining the material’s strange behavior and to finding new ways to manipulate it.

For decades, researchers have argued about the mechanism behind the transition. One possibility is that the atoms in the crystal shift collectively and simultaneously, creating the polarized state from a previously unpolarized lattice, much as a crowd forms from scattered individuals. The alternative is that the tiny polar islands exist all along, even at temperatures where the material shows no net polarization, and that cooling simply persuades them to orient in the same direction, the way an already-assembled crowd might all turn to face the same stage. Distinguishing between these scenarios is extraordinarily difficult, because the islands are so small and the signals they produce are so faint that conventional measurements struggle to resolve them. The Auburn team’s results provide strong evidence for the second picture: the polar nanoregions are already present before the material orders, and the transition consists of their alignment rather than their creation.

Seeing that evidence required an instrument of unusual sensitivity. Led by Wencan Jin, the Thomas and Jean Walter Endowed Associate Professor in Auburn’s Department of Physics, and graduate student Mohamed Kandil, the researchers built a laser-based optical measurement system capable of detecting how the crystal altered incoming light. Because polar regions interact with light in ways that depend on their orientation, the way the crystal scattered and modified a probe beam revealed whether the islands inside were pointing randomly or had settled into preferred directions. By repeatedly warming and cooling the sample and watching the optical signal evolve, the team could track the alignment process across the order-disorder phase transition, the temperature boundary at which the material passes from a disordered state into an organized one. At higher temperatures the islands pointed every which way; as the crystal cooled, they locked into shared orientations.

The more striking result came next. The researchers demonstrated that light itself could do the aligning. When they struck the crystal with brief laser pulses, regions that would otherwise have remained disorganized at warmer temperatures were driven into alignment, and the team’s optical measurement allowed them to detect the resulting pattern. This technique, described in the study as optical poling, effectively substitutes a pulse of light for the cooling that would normally be required to order the material. The induced alignment lasted only about a picosecond, or one trillionth of a second, before the islands relaxed back into disorder. Even so, the demonstration that such order can be both created and read out optically, on ultrafast timescales, opens a route to investigating extremely fast ways of handling information, a prospect with potential relevance to future optoelectronic technologies that process and store data using light rather than slow electrical currents.

The experiment’s success was hard won. The project traces its origins to the 2023 American Physical Society March Meeting, where Jin connected with researchers at Japan’s National Institute of Advanced Industrial Science and Technology who had the expertise to grow the high-quality modified strontium titanate crystals the measurements demanded. Back in Auburn, the team then spent nearly a year refining and improving its equipment before it could detect the islands’ faint optical signal at all. Even with that hurdle cleared, a further challenge remained: capturing the fleeting instant when a laser pulse brought the disordered regions into alignment, a window measured in trillionths of a second.

That moment finally arrived in 2025. The breakthrough came when Kandil observed the disordered polar regions becoming aligned under laser illumination, Jin recalled, describing the emergence of the signal as a thrilling moment for the team. For Kandil, the study represents his first publication and the culmination of three years of experimental work. Jin described the project as Kandil’s odyssey, noting that it took three years of dedication to complete the work and achieve the result. The persistence paid off not only in a publication but in a measurement that many groups attempting to resolve polar nanoregions have found elusive, precisely because the optical signatures of these tiny structures are so weak.

The scientific significance of the work lies in what it settles and what it enables. On the explanatory side, the findings support the view that electric order in this quantum ferroelectric metal emerges through the alignment of pre-existing polar regions rather than their spontaneous creation, resolving the long-standing debate for this material in favor of the alignment picture. On the practical side, the study establishes an optical approach to controlling those regions. Instead of relying on electrodes, electric fields, or slow thermal cycling, researchers can now use femtosecond-scale laser pulses to write order into the material and optical probes to read it back out, all within a picosecond. That combination of writing and reading by light is a prerequisite for any future technology that hopes to exploit polar nanoregions as ultrafast, nanoscale elements for information processing or storage.

The choice of material matters as much as the technique. Ferroelectric metals are rare and counterintuitive substances in which electrical conduction and polar order coexist, a combination that ordinary ferroelectric insulators do not offer. Modified strontium titanate belongs to a class of quantum materials whose collective behaviors, including superconductivity and other emergent phenomena, are thought to be intertwined with the polar fluctuations hosted in the lattice. Being able to align, disalign, and monitor the polar nanoregions on demand gives physicists a new experimental knob for probing how these fluctuations influence the material’s broader quantum behavior, potentially illuminating connections that have been difficult to test directly.

For the Auburn group, the findings mark the beginning of a research program rather than its end. By using light to detect and control tiny, rapidly changing electrical regions, the team has opened a window into materials whose hidden patterns were previously accessible only indirectly. The picosecond lifetime of the light-induced order is, in this context, less a limitation than a feature: it demonstrates that the alignment dynamics can be initiated and observed on the same ultrafast timescales on which future optoelectronic devices would need to operate. What began as a decades-old question about how a crystal organizes itself has become, thanks to a flash of light and years of patient instrument-building, a working demonstration that order in a quantum material can be summoned, seen, and perhaps someday put to use at the speed of light.

Subject of Research: Ultrafast optical control of polar nanoregions in a quantum ferroelectric metal

Article Title: A flash of light brings order to a quantum material

Article References: A flash of light brings order to a quantum material. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: ferroelectricity, polar nanoregions, strontium titanate, ultrashort laser pulses, optical poling, phase transition, quantum materials, ultrafast optics, condensed matter physics, Physical Review Letters, optoelectronics, Auburn University

The phenomenon at the center of the work is the barocaloric effect, the pressure-driven cousin of the magnetocaloric, electrocaloric and elastocaloric effects that have energized the field of solid-state cooling. When a material sits near a phase transition, applying pressure can shift the transition temperature and drive the material from one thermodynamic state to another. Because the two states carry very different amounts of entropy, squeezing the material and then releasing it forces heat to be absorbed or dumped, effectively pumping thermal energy with nothing more than a mechanical push. If the process is reversible and the entropy change is large, the material becomes a candidate for refrigerators and heat pumps that contain no volatile liquids whatsoever.

Pentaglycerine belongs to a family of substances known as plastic crystals, organic molecular solids that undergo dramatic order–disorder transitions. Below the transition, the molecules sit in a well-ordered crystal lattice, locked into position by a network of hydrogen bonds between their hydroxyl groups. Above it, the molecules remain in the solid but begin to rotate and tumble around their lattice sites, a state that behaves in some ways like a crystalline liquid. This molecular liberation absorbs an enormous amount of entropy, which is precisely what makes plastic crystals so attractive for barocaloric applications. The transition temperature is also unusually sensitive to pressure, meaning modest mechanical forces can switch the material back and forth.

To characterize pentaglycerine rigorously, the team deployed an unusually broad experimental arsenal. Temperature-dependent synchrotron X-ray diffraction, performed at the Pohang Light Source, tracked how the crystal structure evolves through the transition, while Raman spectroscopy probed the vibrational fingerprints of the molecular ordering. High-pressure micro-differential scanning calorimetry measured the heat flows associated with the transition under applied pressures, revealing how the transition temperature climbs as the sample is squeezed. Together these techniques pinned down the ordered-crystal to plastic-crystal transformation across a temperature window of roughly 353 to 363 kelvin, accompanied by a discontinuous jump in specific volume of 0.05 cubic centimeters per gram, a substantial structural breathing that accompanies the molecular disordering.

The calorimetry established the key numbers that define the material’s cooling credentials. At ambient pressure, the transition occurs at 357 kelvin on heating and 347 kelvin on cooling, a hysteresis that reflects the first-order nature of the transformation. Most importantly, the transition temperature shifts by 0.13 kelvin per megapascal of applied pressure. That pressure sensitivity is the engine of the barocaloric effect: it dictates how far a given pressure can push the material through its transition. Under an applied pressure of 80 megapascals, pentaglycerine delivered a peak isothermal entropy change of 476 joules per kelvin per kilogram and an adiabatic temperature change of 9.3 kelvin, figures that place it firmly among the leading barocaloric materials reported to date.

What distinguishes this study is that the measurements did not stop at the macroscopic level. The researchers paired their experiments with molecular dynamics simulations of the two phases, equilibrating the ordered crystal and the plastic crystal independently and comparing them at the experimentally determined transition temperature. The simulated volume difference between the phases matched the measured discontinuity from X-ray diffraction, a satisfying cross-validation that suggests the simulations capture the essential physics. The simulations also revealed the microscopic origin of the entropy change: the plastic-crystal state exhibits lower hydrogen-bond connectivity and a less favorable hydrogen-bond environment than the ordered phase, meaning the transition is fundamentally a story about the breaking and rearranging of the hydroxyl network that glues the molecules together.

Pressure, it turns out, does more than simply shift the transition temperature. By comparing the two phases across a range of applied pressures, the team found that the difference in total Coulombic interaction energy between the ordered and plastic states grows from 8.3 kilojoules per mole at ambient pressure to 12.1 kilojoules per mole at 160 megapascals. Expressed relative to the simulated phase enthalpy difference, that electrostatic contribution rises from roughly 58 percent to 81 percent. In other words, compression does not just squeeze the lattice; it progressively reshapes the energetic balance of the transition, making electrostatic interactions an increasingly dominant player. This pressure-resolved energetic picture had never been drawn for pentaglycerine before, and it offers a mechanistic explanation for why the material’s barocaloric response behaves the way it does under load.

To close the loop between simulation and experiment, the researchers constructed two independent thermodynamic estimates of the transition entropy from their simulated enthalpy and volume differences and compared them directly with the calorimetric measurements across the full pressure range from 0.1 to 160 megapascals. The agreement between the computational and experimental entropy estimates provides a template for how future barocaloric materials should be evaluated: not with isolated measurements or isolated simulations, but with a pressure-resolved framework in which each validates the other. Such cross-checked frameworks are essential if the field is to move from serendipitous discoveries to rational materials design.

The broader context makes the work timely. Previous studies have documented colossal barocaloric effects in related plastic crystals such as neopentyl glycol, and recent reports have extended the concept to organic ionic plastic crystals, metal-organic frameworks, zeolitic imidazolate frameworks and even n-alkanes undergoing liquid–solid transitions. Machine learning approaches are now being used to screen candidate materials at scale, and barocaloric composites have been fabricated by 3D printing for practical thermal management. Yet the microscopic question of exactly what pressure does to the intermolecular forces that drive the transition has often been left unanswered. By tying the macroscopic entropy change of pentaglycerine to its hydrogen-bond network and its evolving electrostatic energy landscape, the Korean team has supplied precisely that missing link.

There are, of course, practical hurdles before pentaglycerine cools your kitchen. Its transition temperature near 350 kelvin positions it for heat-storage and waste-heat recovery applications rather than room-temperature refrigeration, and operating pressures on the order of tens to hundreds of megapascals demand robust mechanical engineering. But the study’s framework applies to the whole plastic-crystal family, and the insight that hydrogen-bond connectivity governs the entropy change gives chemists a concrete design lever: tune the hydroxyl network, and you tune the cooling power. As global cooling demand is projected to climb steeply toward mid-century, materials that can move heat with a squeeze instead of a polluting gas are no longer a laboratory curiosity. Pentaglycerine, probed with synchrotron light, calorimeters and supercomputers alike, has just shown how far that idea has come.

Subject of Research: Pressure-dependent barocaloric cooling effect and phase transition mechanisms of the plastic crystal pentaglycerine

Article Title: Experimental and molecular dynamics investigation of the pressure-dependent barocaloric response of pentaglycerine

Article References: Experimental and molecular dynamics investigation of the pressure-dependent barocaloric response of pentaglycerine. (n.d.). https://doi.org/10.1007/s10853-026-13872-9

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13872-9

Keywords: barocaloric effect, pentaglycerine, plastic crystals, solid-state cooling, phase transition, molecular dynamics, hydrogen bonding, high-pressure calorimetry, X-ray diffraction, entropy change, thermal energy storage, refrigerants

The physics at the heart of the experiment concerns stacking order. When graphene sheets are stacked, each successive layer can sit in slightly different registries relative to the layer beneath it. In the most common configuration, known as Bernal stacking, alternate layers align in a pattern that gives the material an ordinary, semimetallic electronic structure. A second arrangement, rhombohedral stacking, shifts each layer by the same registry offset in sequence, producing a dramatically different electronic landscape. Rhombohedral multilayer graphene has emerged in recent years as one of the richest platforms in condensed matter physics, hosting superconductivity, orbital ferromagnetism, and exotic topological states that are entirely absent in Bernal-stacked samples of the same thickness. The catch is that rhombohedral stacking is metastable, and growing devices in which the desired stacking is stable and well controlled has been a persistent challenge.

The Cornell team, led by corresponding author Kenji Yasuda, took advantage of the fact that these two stacking arrangements can be converted into one another by sliding entire layers laterally across each other. Because the layers in graphene are held together only by weak van der Waals forces, the energy barrier between registries is small enough that an electric field, and the carrier density it induces, can tip the balance. Earlier work by other groups had shown that doping and electric fields can influence stacking transitions in few-layer graphene, and that interlayer sliding in van der Waals materials can produce ferroelectric-like switching of polarization. What distinguishes the new study is the demonstration that this structural sliding transition can be harnessed as a non-volatile toggle for a collective magnetic phase, converting a structural degree of freedom into magnetic functionality.

Experimentally, the researchers fabricated devices from marginally twisted double-bilayer graphene, effectively four carbon layers held between top and bottom gates in a dual-gated Hall bar geometry. In such a device, sweeping the carrier density n and the displacement field D gives experimenters two independent knobs: n controls how many electrons or holes populate the layers, while D controls how asymmetrically charge is distributed between the top and bottom of the stack. By measuring longitudinal resistance as the gates were swept forward and backward, the team observed clear bistable switching between a Bernal-dominant configuration and a mixed state containing both rhombohedral and Bernal domains. The hysteresis in the resistance indicates a first-order structural phase transition: rather than sliding smoothly, the layers snap between registries, retaining whichever state they were last driven into until a sufficiently different gate condition pushes them back.

The phase diagram the team mapped out is remarkably broad, with the bistable switching persisting across a wide swath of the carrier density and displacement field plane. Quantum oscillation measurements confirmed the structural interpretation. In regions of the device identified as Bernal-dominant, Landau fan diagrams aligned with the known spectrum of Bernal tetralayer graphene, while the mixed regions displayed blurred oscillations consistent with a nearly equal coexistence of rhombohedral and Bernal domains. Strikingly, the hysteresis in the longitudinal resistance persisted all the way up to room temperature, indicating that the structural transition itself is robust and does not rely on cryogenic conditions. The magnetic phase that emerges from it, however, lives at much lower temperatures, with a Curie temperature of around 8 kelvin in parts of the phase space and closer to 2 kelvin elsewhere.

That magnetic phase is the central discovery. When the device is in the rhombohedral-Bernal mixed state, low-temperature transport measurements reveal an anomalous Hall effect: a transverse voltage that appears even at zero external magnetic field and shows hysteresis under magnetic field sweeps, the classic fingerprint of ferromagnetism. When the device is switched back into the Bernal-dominant state, the anomalous Hall signal vanishes. The authors demonstrated that this switching between magnet and non-magnet is non-volatile and repeatable: by cycling the gate voltages through the same sequence, they could repeatedly write and erase the ferromagnetic phase at a fixed set of gate values, with the state of the device determined entirely by its sweep history. The magnitude of the anomalous Hall signal stayed roughly consistent across cycles, although the coercive field varied between sweeps, a variability the authors attribute to the small magnetic energy scale of the ferromagnetism in their sample.

One of the most intriguing technical observations concerns the origin of the Hall signal itself. When the researchers applied opposite displacement fields, the sign of the anomalous Hall response reversed. This behavior led the authors to suggest that the Hall signal may originate not from the bulk of the rhombohedral regions but from the domain boundaries where Bernal and rhombohedral regions meet. Such boundaries are known in the graphene literature to host interesting electronic behavior, including topological valley transport, and in this system they may act as the conduits through which the ferromagnetic order produces its anomalous Hall response. Understanding exactly how domain walls between stacking regimes carry or mediate magnetic order is one of the questions the work leaves open, and the authors note that a full accounting of the resistance changes tied to domain configuration will require simultaneous real-space imaging and transport measurements.

The broader significance of the result lies in its demonstration that structural phase transitions in two-dimensional materials can serve as an on-demand control mechanism for complex electronic phases. In conventional phase-change materials, structural switching is used for memory applications, but the phases involved are typically distinguished by resistivity rather than by magnetism. In two-dimensional magnets such as chromium triiodide, pressure and strain have been shown to tune magnetic order, but those materials require magnetic atoms to exist in the first place. The graphene device here achieves magnetic switching in an elementally pure carbon system, where the magnetism is an emergent consequence of correlated electron behavior in a particular stacking arrangement. This decouples the magnetic functionality from any specific magnetic element and ties it instead to geometry, which can be manipulated electrically with van der Waals sliding.

There are, of course, substantial gaps between a low-temperature laboratory device and a practical technology. The ferromagnetic phase survives only at a few kelvin, the coercive fields fluctuate from cycle to cycle, and the domain configurations that underlie the switching appear to vary between preparations, producing scan-to-scan scatter in the hysteresis. Yet the structural switching itself endures to room temperature, and the strategy of using gate-induced sliding as a first-order transition between competing stacking polytypes is applicable in principle to other van der Waals materials where stacking governs exotic phases. As research into rhombohedral graphene continues to reveal superconductivity, fractional Chern insulators, and chiral superconducting candidates, the ability to switch between stacking regimes without rebuilding the device offers a new dimension of control. For now, the Cornell experiment stands as a vivid proof of concept: atoms slid by an electric field can turn a carbon crystal into a magnet, and back again, on command.

Subject of Research: Gate-induced layer sliding and stacking-order control of non-volatile magnetic switching in tetralayer graphene

Article Title: Gate-induced layer sliding drives non-volatile switching of magnetism in tetralayer graphene

Article References: Gate-induced layer sliding drives non-volatile switching of magnetism in tetralayer graphene. (n.d.). https://doi.org/10.1038/s41565-026-02306-x

Image Credits: AI Generated

DOI: 10.1038/s41565-026-02306-x

Keywords: graphene, layer sliding, rhombohedral stacking, Bernal stacking, ferromagnetism, anomalous Hall effect, non-volatile switching, two-dimensional materials, van der Waals, gate voltage, phase transition, stacking domains

To understand why this matters, it helps to consider how quantum computers differ from the machines on our desks. Conventional computers store information in bits, each of which is either a 0 or a 1. Quantum computers use qubits, which can exist in a superposition, meaning they hold multiple possibilities between 0 and 1 until they are measured, at which point each produces one result or the other. This strange property, governed by the unusual rules that govern atoms and other extremely small particles, is what gives quantum computers their potential power. It is also what makes the information they carry so sensitive. Heat, stray electromagnetic signals, imperfect control pulses and tiny flaws in the hardware can all alter a qubit’s state, and over time the resulting errors can accumulate until a calculation can no longer be trusted.

The challenge of keeping a quantum computer on track is compounded by two fundamental restrictions that do not apply to ordinary computing. Unlike ordinary computer data, quantum information cannot simply be copied for safekeeping. And measuring it can change or destroy the very state being used. A fault-tolerant machine must therefore repeatedly detect and correct errors without losing the information it is meant to protect. Scaling quantum computers will require them to identify and correct errors while they are working, a capability known as error correction, which will allow for the construction of a fault-tolerant quantum computer. Such a device would be able to keep computing correctly even though its individual quantum bits are constantly making small mistakes. No one has yet built one.

“To build a fault-tolerant quantum computer, we have to make these checks and corrections not just once or twice, but a huge number of times during a calculation,” said Jedediah Pixley, a professor in the Department of Physics and Astronomy at the Rutgers School of Arts and Sciences and Director of the Center for Materials Theory, who is one of the senior authors of the study and a member of the Flatiron Institute, the scientific research division of the Simons Foundation in New York. “This experiment is a landmark on that road. It says, ‘OK, we’ve taken another important step to get there.'”

The experiment was conducted on a 156-qubit IBM Quantum Heron processor, one of the most powerful quantum processors in the world, with the researchers selecting a connected chain of as many as 100 qubits. The team programmed the system to alternate between two competing tasks. The first acted like a scrambler: it mixed information among neighboring qubits, spreading chaos through the system in much the same way that repeatedly shuffling a deck of cards makes the original order increasingly difficult to recognize. The second task served as a form of control: the computer checked individual qubits and reset them when necessary. Repeated often enough, those resets pushed the system toward a simple, orderly state selected by the researchers.

Overall, the team performed nearly 5,000 operations that linked pairs of qubits, along with nearly 5,000 checks and resets. According to the researchers, it was the largest successful demonstration of this approach to date. “The challenge was not simply to measure a qubit, but to do it repeatedly while the rest of the processor continued to operate,” said Maika Takita, principal research scientist for quantum error correction and dynamic circuits experiments at IBM, and another senior author of the study. “This experiment shows that present-day hardware can coordinate quantum operations, measurements and resets thousands of times across a large system.”

The researchers controlled how often the computer performed each task, and by changing that balance they could see whether scrambling or resetting would take over. When scrambling occurred more than half the time, chaos won and the system remained chaotic. When checking and resetting occurred more often, control won and the researchers could guide the qubits toward the orderly state they wanted. At roughly a fifty-fifty split, a slight change in which task occurred more often suddenly changed the entire system. Physicists call such a dramatic shift a phase transition, like water freezing into ice. Here, the qubits shifted together from chaotic behavior to a state the researchers could control, confirming a theoretical prediction that order can emerge from disorder in this setting.

“Small changes can lead to large and nearly impossible-to-predict consequences, like the classic idea that a butterfly flapping its wings in Africa could eventually contribute to a hurricane hitting Louisiana,” said Justin Wilson, an associate professor of physics at Louisiana State University and a study coauthor. “But this out-of-control behavior can be brought under control by randomly intervening, and there is a sharply defined rate at which that happens. It wasn’t obvious that this transition between chaos and control would survive in quantum physics, but our results show that it does.”

The project itself began in an unusually informal setting: a friendly bet at a 2021 birthday party for Pixley’s wife, while he was still at Rutgers and living in Highland Park, New Jersey. His longtime collaborator Sriram Ganeshan wagered that a puzzling quantum effect had a counterpart in ordinary physics, leading the group to develop a new theory about controlling quantum chaos. A chance conversation with IBM physicist Barbara Jones then helped turn that theory into an experiment. Pixley lost the bet and paid up with two scoops of blueberry ice cream, after Ganeshan and others joined him at the Aspen Center for Physics in Aspen, Colorado. What began as a party wager ultimately produced a theoretical framework robust enough to be tested on one of the world’s most advanced quantum processors.

The IBM processor allowed the researchers to test their theory on systems of up to 100 qubits, far beyond the roughly two dozen they could simulate on conventional computers, and the results closely matched their predictions. “What was striking was that the transition became more clearly defined as we studied larger systems,” said Haining Pan, a Rutgers postdoctoral researcher at the time of the study and a co-first author. “The agreement between the experiment and the theory showed that this was not an accidental feature of a small circuit. It was collective behavior emerging across the quantum system.” In addition to Rutgers and IBM, researchers affiliated with the City College of New York, the CUNY Graduate Center, Iowa State University, Ames National Laboratory, Pennsylvania State University and Louisiana State University contributed to the study. As the field moves toward machines that can correct their own mistakes in real time, this experiment offers both a technical milestone and a demonstration that theoretical predictions about quantum chaos can be verified at scales where collective behavior, not just individual qubits, takes center stage.

Subject of Research: Real-time feedback control and error correction in quantum computers

Article Title: Scientists move a step toward quantum computers that can correct their own mistakes

Article References: Scientists move a step toward quantum computers that can correct their own mistakes. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: quantum computing, error correction, fault tolerance, qubits, quantum chaos, phase transition, IBM Quantum Heron, feedback control, Rutgers University, Nature Physics, quantum information, scrambling

The motivation behind the work is rooted in a growing tension of modern life. High-frequency electromagnetic fields are everywhere, emitted by power lines, communication systems, imaging technologies, and the dense infrastructure of 5G and 6G wireless networks and satellite communications. While short-term exposure within prescribed safety limits is generally considered minimal risk, long-term exposure to high-frequency radiation has been associated with detrimental effects on human health and ecosystems. In industrial settings, local field intensities can spike unexpectedly when multiple sources overlap or when equipment malfunctions, yet most monitoring today relies on bulky, powered instruments that cannot be worn or embedded cheaply in every device that might pose a hazard.

There is also a security dimension. High-frequency fields are the physical medium of electromagnetic pulse weapons, which can be used defensively but also maliciously in cyberterrorism. Real-time, in-situ detection of destructive electromagnetic fields would significantly enhance risk management for command-and-control systems and battlefield operations. Drone warfare, in particular, demands simple onboard microsensors capable of detecting and alarming potential electromagnetic attacks. Existing sensor technologies, from Hall effect devices and anisotropic magnetoresistance elements to giant magnetoresistance and spin-dependent tunneling sensors, offer compact designs with medium-to-high accuracy, but they all require detection electronics powered by external energy supplies, limiting their mobility and their usefulness in passive, wearable formats.

The new chip takes a radically different approach by exploiting a magnetothermal mechanism. At its heart is a thin, flat cell filled with the thermotropic liquid crystal 4-cyano-4′-pentylbiphenyl, better known as 5CB, a rod-like nematic compound that has served as a model material since its first synthesis in 1973. Embedded within the liquid crystal matrix is a network of thin ferromagnetic wires, a 50-mesh nickel gauze with wires roughly 50 micrometers in diameter. Both sides of the chip are laminated with polymer-based polarizer films aligned at 90 degrees to each other, forming crossed polarizers in direct contact with the liquid crystal. The assembled device measures about one centimeter square, weighs less than 0.3 grams, and has a Young’s modulus on the order of tens of kilopascals, making it flexible and light enough for integration into smart glasses or miniature unmanned aerial vehicles.

The physics of the sensing process unfolds in two coupled steps. First, when an external alternating magnetic field exceeds roughly 6 millitesla at the tested frequency of 125 kilohertz, the time-varying field induces eddy currents in the conductive nickel mesh, generating Joule heating. Because nickel has a high relative permeability, it concentrates the magnetic field, increasing the induced currents and heating efficiency compared with a non-magnetic mesh. A second mechanism, magnetic hysteresis loss, contributes additional heat that occurs only in ferromagnetic materials and is proportional to the area under the magnetization loop. The heating power scales with the square of the product of field strength and frequency, which means even modest increases in either parameter dramatically accelerate the response.

Second, the heat generated in the mesh diffuses into the surrounding liquid crystal. Once the local temperature surpasses the clearing point of 5CB at about 35 degrees Celsius, the material undergoes a reversible phase transition from the nematic phase, in which the rod-like molecules are quasi-one-dimensionally ordered, to the isotropic phase, in which they are globally disordered. This transition changes the optical properties of the film dramatically. In the nematic, field-off state, the unaligned liquid crystal exhibits strong birefringence between the crossed polarizers, so the chip transmits ambient light and appears bright. In the isotropic, field-on state, birefringence vanishes and transmittance drops to near zero, so the chip turns dark. No separate transducer is needed to convert temperature into an optical signal; the phase transition itself is the readout.

In experiments, the researchers placed the chip at the center of a Helmholtz coil driven by an induction heater power supply and filmed its response with a digital camera positioned about 1.5 meters away to shield the camera electronics from interference. When a field of 125 kilohertz and up to 30 millitesla was applied, optically dark domains appeared near the chip center, grew into a ring-like pattern, and rapidly spread to cover most of the display. When the field was switched off, the dark domain gradually shrank and disappeared as heat dissipated by natural convection, completing a full on-off cycle in roughly ten seconds at room temperature. The response time upon induction heating was as fast as 30 milliseconds, while recovery took tens of seconds. The chip showed remarkably high stability and repeatability over more than ten consecutive field pulses.

To understand and predict this behavior, the team built a finite element model in COMSOL Multiphysics that coupled electromagnetic induction with heat transfer and the latent-heat-mediated phase transition. The simulations closely matched the experimental data, predicting the characteristic transition times and optical switching behavior across a wide range of field strengths, generally falling within the standard deviation of the measurements. The model revealed that the onset of the nematic-to-isotropic transition follows a line of constant field-frequency product, suggesting the system operates in the low-frequency regime where heating power scales as the square of that product. The researchers also found that sensitivity increases with the volume fraction of the nickel mesh: a denser mesh generates heat faster and shortens response times, though it also stores more thermal energy and lengthens recovery. Skin-depth effects, estimated at about 30 micrometers at 125 kilohertz, comparable to the wire diameter, add a further frequency-dependent wrinkle to the design space.

The material choices are deliberately pragmatic. 5CB is cheap, easy to handle, and stable at room temperature thanks to long-term supercooling of its nematic melt, and its low viscosity, volatility, and toxicity make it practical for real devices. Its clearing temperature of 35 degrees Celsius suits temperate climates, but the authors note that alternative or blended liquid crystals with higher transition temperatures, such as MBBA at 47 degrees Celsius, could extend operation to warmer subtropical environments, while lower-transition materials could serve aerospace applications. Tuning the mesh geometry, wire diameter, or liquid crystal composition offers further control over sensitivity and response time, and coating the wires with anchoring agents could better align the liquid crystal molecules for improved performance.

The combination of extreme simplicity, millimeter-scale dimensions, lightweightness, passive operation, and a robust visual readout positions this chip as a promising candidate for ultra-low-power wearable technologies, mobile platforms, and electronic warfare systems. Because the sensor is fundamentally independent of electronics, it is also inherently resistant to external field-induced signal noise that plagues conventional detectors. The researchers caution that the thermally driven mechanism is slower than the millisecond intrinsic reorientation of the liquid crystal itself, spanning from several milliseconds at high fields to tens of seconds near the detection limit, and that future work will explore faster liquid crystal formulations inspired by electro-optical sensing modes. Even so, the demonstration that electromagnetic radiation can be caught, converted, and displayed by a chip with no power source of its own marks a striking step toward a world where hazard warnings are woven invisibly into the fabric of everyday objects.

Subject of Research: Passive liquid crystal sensor chip for detecting high-frequency electromagnetic fields

Article Title: Electronics-free, ultra-low-power, wearable sensor chip for high-frequency electromagnetic field detection

Article References: Mohizin, A., Abelmann, L., & Sung, B. (2026). Electronics-free, ultra-low-power, wearable sensor chip for high-frequency electromagnetic field detection. Communications Engineering, 5(1), Article 170. https://doi.org/10.1038/s44172-026-00800-7

Image Credits: AI Generated

DOI: 10.1038/s44172-026-00800-7

Keywords: liquid crystals, electromagnetic field sensor, wearable technology, magnetothermal effect, nickel mesh, 5CB, passive sensing, radio-frequency detection, phase transition, electronics-free, electromagnetic pulse, birefringence

The experiment, published in Nature Physics, was performed on an IBM superconducting quantum processor with up to 100 qubits. The team implemented a quantum version of the Bernoulli map, a textbook example of a classically chaotic dynamical system in which each step of the evolution stretches and folds the space of possibilities, rapidly amplifying any tiny perturbation. On the quantum side, this chaotic evolution has a dramatic consequence: it scrambles quantum information, spreading local information across the entire entangled state of the qubit register in much the same way that a drop of ink diffuses through a churning fluid. Left alone, the quantum state races toward an effectively maximally scrambled, thermal-like configuration that carries no memory of where it began.

To fight back against this scrambling, the researchers used adaptive monitored quantum circuits. The key ingredients are mid-circuit measurements and resets: the processor periodically measures individual qubits while the computation is still running, reads out the result, and then applies conditional feedback operations whose choice depends on what was just measured. Each measurement is a non-unitary operation, meaning it does not simply rotate the quantum state but rather collapses part of it, pruning branches of the wavefunction. The classical control loop then steers the dynamics toward a fixed point of the Bernoulli map, the stable destination that a fully controlled classical trajectory would reach. In this scheme, measurement is not a nuisance to be avoided but the very tool used to impose order.

The fundamental tension of the experiment is beautifully simple to state. The chaotic quantum map, built from entangling gates, works relentlessly to spread information and push the system toward quantum scrambling. The measurement-and-feedback machinery works in the opposite direction, repeatedly collapsing the state back toward a classical fixed point. Which force wins determines the character of the dynamics. When chaos dominates, the qubits end up in a scrambled quantum state that remembers nothing of its origin. When feedback dominates, the system settles into a stable, classically controlled configuration locked to the map’s fixed point. Between these two regimes, the collaboration predicted and then observed a dynamical phase transition, a critical point where the nature of the steady state changes abruptly as the balance of control is tuned.

Phase transitions are usually discussed in equilibrium thermodynamics, where water freezes into ice or a magnet loses its magnetization as temperature changes. But over the past several years, physicists have discovered that entirely analogous sharp transitions occur in the dynamics of open quantum systems. The best studied example is the measurement-induced phase transition, predicted independently in 2018 and 2019 by several groups: in a circuit that combines entangling gates with random measurements, the entanglement properties of the evolving state change qualitatively at a critical measurement rate. Those theoretical predictions were confirmed experimentally in 2022 and 2023 on superconducting and trapped-ion platforms. The new work extends this program in a crucial direction: rather than merely measuring, the circuit uses measurement outcomes to actively control chaotic dynamics, connecting the modern theory of monitored quantum circuits to the classical science of chaos control.

The scale of the experiment is what makes it remarkable. The team applied up to nearly 5,000 entangling gates and nearly 5,000 non-unitary mid-circuit operations on systems of up to 100 qubits, sustaining a measurement-and-feedback protocol over circuit depths that would have been unthinkable on early quantum hardware. Crucially, despite the noise and decoherence that plague any present-day processor, the device produced accurate estimates of universal critical properties, the quantitative fingerprints of the phase transition that do not depend on microscopic details. This shows that mid-circuit measurement, the same primitive that underpins quantum error correction, has matured to the point where it can serve as a genuine instrument of many-body physics rather than just a tool for correcting errors.

Interpreting such an experiment is a formidable theoretical challenge, because the very size of the 100-qubit Hilbert space forbids direct classical simulation of the full state. The collaboration therefore deployed a battery of complementary techniques. Noisy simulations of smaller systems captured the essential physics on sizes that classical computers can handle. Matrix product states, a tensor-network method that efficiently represents the mildly entangled states produced by measurement, extended the accessible system sizes. Finally, mappings onto statistical mechanics models allowed the team to identify the universality class of the transition, connecting the circuit dynamics to well-understood critical phenomena. The agreement between the hardware data and these theoretical tools provides strong evidence that the observed transition is a genuine critical phenomenon rather than an artifact of device noise.

The paper also reports an analysis of the quantum fluctuations of magnetization across the transition, measured through the Kullback-Leibler divergence, an information-theoretic quantity that quantifies how one probability distribution differs from another and whose system-size scaling reveals the critical point. Figures of this scaling, together with maps of the long-time steady state and the dynamical buildup of the transition, constitute the central evidence: as the feedback strength crosses a critical threshold, the distribution of outcomes changes shape in a way characteristic of a continuous phase transition, with fluctuations that grow and then reorganize according to universal critical exponents. In effect, the team has watched a quantum system choose, on the basis of control strength alone, whether to behave like a quantum machine or a classical one.

The implications reach in several directions at once. For quantum computing, the demonstration that adaptive, measurement-conditioned circuits can run thousands of non-unitary operations on a hundred qubits is a milestone for the dynamic circuits that future error-corrected machines will rely on. For fundamental physics, it establishes the first experimental realization of a control-induced phase transition, confirming theoretical predictions from 2023 and 2024 that measurement and feedback can drive entanglement and criticality in chaotic systems. And for the classical science of chaos, it extends a program that began with controlling cardiac arrhythmias and chaotic lasers into a regime where the object being controlled is not a trajectory in phase space but an entangled quantum wavefunction. Chaos, it turns out, can be ordered even at the edge of quantum mechanics, one measurement at a time.

Subject of Research: Control of quantum chaos and a quantum-to-classical dynamical phase transition using adaptive measurement-and-feedback circuits on a superconducting quantum processor

Article Title: Order from chaos with adaptive circuits on quantum hardware

Article References: Pokharel, B., Pan, H., Aziz, K., Govia, L. C. G., Ganeshan, S., Iadecola, T., Wilson, J. H., Jones, B. A., Deshpande, A., Pixley, J. H., & Takita, M. (2026). Order from chaos with adaptive circuits on quantum hardware. Nature Physics. https://doi.org/10.1038/s41567-026-03470-6

Image Credits: AI Generated

DOI: 10.1038/s41567-026-03470-6

Keywords: quantum chaos, quantum computing, superconducting qubits, mid-circuit measurement, feedback control, phase transition, monitored quantum circuits, measurement-induced phase transition, quantum scrambling, Bernoulli map, IBM Quantum, Nature Physics

Excitons are bound states formed when an electron, promoted out of its usual place in a crystal, pairs up with the positively charged hole it leaves behind. Like other bosons, excitons can, in principle, condense into a single macroscopic quantum state when cooled sufficiently, producing an exotic phase of matter known as an excitonic insulator. Physicists have made striking progress observing this condensation in engineered low-dimensional systems, such as moiré heterostructures and atomically thin layers, where signatures like perfect Coulomb drag have been reported. But in bulk crystals the story has been far murkier, because the ideal superfluidity of a Bose condensate is nearly impossible when quasiparticles scatter between the bands hosting the electrons and holes.

Instead of long-range quantum coherence, theorists expect a bulk excitonic condensate to manifest as a spatial density order, a superlattice whose period is set by the inverse momentum separation of the bound electrons and holes. The trouble is that such a superlattice looks almost identical to an ordinary charge-density wave, a more mundane ordering of charge driven largely by lattice forces. This ambiguity sits at the heart of the long-running debate over 1T-TiSe2, a quasi-two-dimensional transition metal dichalcogenide that undergoes a phase transition at a critical temperature of roughly 200 kelvin. Earlier momentum-resolved electron energy-loss spectroscopy measurements reported a softening of an electronic collective mode consistent with an exciton condensate’s amplitude mode, but subsequent higher-resolution measurements found no such softening, because Landau damping at finite momentum blurs the signal.

Ultrafast spectroscopy has offered a way around this impasse, since the microscopic interactions underlying excitonic and charge-density-wave orders unfold on distinct timescales. Time-resolved angle-resolved photoemission can track how quickly the spectral gap and folded bands collapse after a laser pulse, and the collapse times depend strongly on the photoexcited carrier density, a hallmark of transient electron–hole dissociation. Yet this technique loses its power above the transition temperature, where long-range order vanishes and only short-range fluctuations remain in the quasi-two-dimensional system. What was needed was a probe sensitive to local electronic structure, one that works even without long-range order.

The Berkeley-led team turned to ultrafast broadband extreme-ultraviolet absorption spectroscopy, a pump–probe technique with element and orbital specificity. The excitonic instability in 1T-TiSe2 originates from the Coulomb attraction between selenium 4p holes and titanium 3d electrons near the Fermi level, so the researchers focused on absorption features involving precisely those states. Guided by first-principles calculations of the orbital-projected density of states, they assigned the observed selenium absorption peaks to transitions from spin–orbit-split selenium 3d core levels into unoccupied selenium 4p states, while the titanium M2,3 edges showed anomalies, including a blueshift of more than two electronvolts and a broad hump spanning 38 to 53 electronvolts, that only time-dependent density functional theory incorporating electron–electron interactions could reproduce.

Among these spectral features, one selenium peak stood out as an ideal reporter. When the team excited the crystal with a 3.4-femtosecond pulse, all the absorption peaks responded within 100 femtoseconds, and coherent oscillations at 6.0 terahertz, corresponding to the A1g phonon in which selenium ions displace out of plane relative to stationary titanium ions, rippled across most of the spectrum. But one selenium peak, labelled peak 2, showed no phonon-induced modulation at all, because its coupling to the A1g mode is negligible. That silence made it a clean window onto the local electronic and excitonic dynamics, free from the interfering rattling of the lattice.

The first surprise came when the researchers lowered the pump fluence nearly tenfold, from 1.7 to 0.2 millijoules per square centimetre, to limit the number of photoexcited carriers. While most transient features scaled down proportionally, the titanium many-body continuum displayed a sign reversal of its transient signal at 200 femtoseconds, a qualitatively different behaviour implying an additional dynamical process beyond simple carrier excitation. Sweeping the sample temperature in roughly 5-kelvin steps across the transition at this low fluence revealed an order-parameter-like onset, showing that this spectral window is sensitive to the establishment of long-range order, likely because the valence charge excitations producing the broad hump are modified by the changing titanium 3d states across the transition.

The selenium peak told an equally compelling story. From a state-filling perspective, its transient transmission decrease reflects an increased number of selenium 4p holes below the Fermi level, holes that could otherwise bind titanium 3d electrons into excitons. At 25 kelvin the decrease was larger than at 310 kelvin, pointing to additional holes released by the break-up of condensed excitons in the ordered state, and temperature-dependent measurements showed a clear onset of this suppression at the critical temperature. Crucially, because this peak is dominated by local dipole transitions, its time-domain signature is agnostic about whether long-range phase coherence exists among the excitons, meaning the team could hunt for excitonic correlations even above the transition.

What they found there is the study’s headline result. The pump fluence controls the transient mobile carrier density, and hence the plasmon frequency, which governs how quickly screening breaks the bound electron–hole pairs; the initial response time should therefore scale as one over the square root of the fluence. Below the transition temperature, the initial suppression indeed became markedly faster as fluence increased, consistent with earlier photoemission measurements. But remarkably, at 300 kelvin, far above the transition, the same trend held: the response visibly slowed at lower fluence, following the same inverse-square-root scaling with a constant offset attributable to the time needed to create mobile holes in the absence of excitonic interactions. The team considered alternative microscopic processes that depend on carrier density, but none could account for the observed fluence- and temperature-dependent trends, leaving short-range excitonic correlations persisting in the normal state as the natural interpretation.

Then came a second surprise at the transition itself. At 190 kelvin, close to the critical temperature, the initial response was consistently fast and roughly independent of pump fluence, breaking the scaling seen everywhere else. Measuring across temperatures from 23 to 350 kelvin at both low and high fluences showed that at low fluence the response time decreases gradually from both sides, reaching a minimum near the transition, while at high fluence it stays short and temperature-independent. The researchers formalized this with a simple model in which the carrier density decomposes into a temperature-independent susceptibility plus a diverging excitonic susceptibility that grows as a power of the inverse distance from the transition. The accelerated hole production near the transition reflects an enhanced excitonic susceptibility, where local excitonic correlations are so fragile that even a weak laser pulse breaks them, analogous to how enhanced phonon fluctuations in diffuse scattering expose a lattice instability. The authors also ruled out a dominant role for charge-density-wave phonons, noting that transient phonon renormalization of about 20 percent could only account for a 20 percent change in response time, dwarfed by the threefold reduction they measured. Because the material is quasi-two-dimensional, the excitonic correlations above the transition are likely confined in-plane, contributing to short-range fluctuations that lack three-dimensional phase coherence, while previous work suggests excitons also maintain interplane coherence in the ordered state. Together, the findings offer a unified picture in which excitonic correlations shape both the amplitude and the phase of the ordered state, and they provide a template, built on element- and orbital-resolved femtosecond spectroscopy, for hunting excitonic instabilities in other bulk candidates such as Ta2NiSe5 and Ta2Pd3Te5.

Subject of Research: Short-range excitonic correlations and enhanced excitonic susceptibility in the excitonic insulator candidate 1T-TiSe2 probed by few-femtosecond extreme-ultraviolet absorption spectroscopy

Article Title: Short-range excitonic correlations and enhanced excitonic susceptibility in 1T-TiSe2

Article References: Zong, A., Lin, S.-C., Sato, S. A., Berger, E., Nebgen, B. R., Hui, M., Lv, B. Q., Cheng, Y., Xia, W., Guo, Y., Xiang, D., & Zuerch, M. W. (2026). Short-range excitonic correlations and enhanced excitonic susceptibility in 1T-TiSe2. Nature Physics. https://doi.org/10.1038/s41567-026-03423-z

Image Credits: AI Generated

DOI: 10.1038/s41567-026-03423-z

Keywords: excitons, excitonic insulator, 1T-TiSe2, charge-density wave, ultrafast spectroscopy, extreme ultraviolet, phase transition, quantum materials, transition metal dichalcogenide, excitonic susceptibility, femtosecond pump-probe, condensed matter physics

Active fluids are a strange class of matter. Their microscopic constituents — motor proteins dragging filaments, bacteria propelling themselves through liquid — continuously convert chemical energy into motion, keeping the system permanently out of equilibrium. At low driving, the flows are weak and disorganized. Crank up the activity, and the fluid erupts into a self-sustained storm of vortices and jets known as active turbulence. The problem, the authors argue, is that unlike ordinary inertial turbulence, where well-established control parameters and asymptotic regimes exist, active turbulence has never had a clear dividing line separating a weakly disordered flow from a genuinely collective, system-scale state. Equilibrium statistical physics classifies phases through free energies, symmetry breaking and universal scaling, all rooted in detailed balance — tools that driven systems, lacking an underlying free energy, do not obviously inherit.

The team’s solution borrows from one of the most elegant developments in modern mathematical physics: Schramm–Loewner evolution, or SLE. SLE describes a one-parameter family of random, conformally invariant curves, labeled by a diffusivity κ, that arise as the scaling limits of interfaces in critical two-dimensional models. Specific values of κ correspond to famous systems — loop-erased random walks at κ = 2, Ising model interfaces at κ = 3, and critical percolation cluster boundaries at κ = 6. Because the parameter fully determines the curve statistics, measuring κ in a complex system provides a stringent test of whether that system shares the universality class of a known critical model. Demonstrating SLE behavior also implies conformal invariance — invariance under translations, rotations, rescalings and angle-preserving transformations — an exceptionally restrictive symmetry that tightly constrains the geometry of fluctuations across all scales.

Previous work had hinted that living matter might possess such hidden symmetry. In epithelial cell layers and bacterial colonies, the nodal lines of the vorticity field — the zero-vorticity contours separating regions of clockwise and counterclockwise rotation — had been found to follow the statistics of critical percolation, corresponding to SLE with κ = 6. But it remained unclear whether these statistics reflected a robust transition controlled by activity or were incidental features of particular biological systems. The new study settles the question by combining two independent experimental platforms with large-scale simulations. The first experiment used the canonical microtubule–kinesin active nematic, where activity is tuned through ATP concentration; the second used dense suspensions of swimming Bacillus subtilis, where oxygen availability controls self-propulsion.

The results were strikingly consistent. In the microtubule–kinesin system, at ATP concentrations above roughly 18 micromolar, the extracted vorticity nodal lines obeyed the analytical left-passage probability prediction for κ = 6, and the Loewner driving function behaved as a Brownian process with variance growing linearly in time at exactly the rate expected for SLE6. Below about 8 micromolar ATP, both signatures vanished. In the bacterial suspensions, high-oxygen conditions produced the same critical percolation statistics, while oxygen depletion — with the transition estimated to fall between 0.07 and 0.125 millimolar dissolved oxygen — destroyed them. Crucially, the velocity and vorticity fields look visually indistinguishable on either side of the threshold; the difference is not in how the flow appears, but in the symmetry class of its geometry.

Simulations revealed why. In the hydrodynamic active nematic model, where a nematic order parameter couples to flow through an active stress proportional to the activity parameter ζ, the same SLE6 signatures emerge only above a critical activity ζc. Below that threshold, the left-passage probability deviates from the analytical form and the driving function loses its Brownian character. Within the SLE framework, this breakdown corresponds directly to the loss of conformal invariance. The activity-controlled crossover is therefore a genuine symmetry-breaking transition — but of an unusual kind, in which the symmetry gained or lost is conformal, imposing exceptionally strong constraints on the flow geometry across scales. Even more remarkably, when the team replaced explicit active stress with stochastic forcing in a fluctuating nematohydrodynamic model, the conformally invariant state still appeared whenever detailed balance was violated, and disappeared when the fluctuations were constrained to satisfy the fluctuation–dissipation relation. Conformal symmetry, it turns out, is a generic consequence of non-equilibrium driving, not a property of any particular microscopic mechanism.

The transition is not merely geometric. Vortices are carriers of stress and momentum, so the team went on to ask how the vortex population reorganizes at the same threshold. Detecting vortex cores from the winding of the velocity field and connecting nearby vortices into geometric graphs, they found that below the transition, a spanning cluster forms only at connection distances far larger than the natural vortex spacing, while above ζc the percolation threshold snaps to roughly one characteristic length. More tellingly, a rigidity percolation analysis using the pebble game algorithm showed that precisely at ζc, a giant mechanically rigid cluster spanning the entire system emerges — the flow switches from a floppy collection of independent vortices to a self-supporting mechanical network. Both experimental systems showed the same trend, with high-activity states exhibiting larger geometric clusters and rigid clusters than their low-activity counterparts.

A third, fully independent diagnostic came from topology. Using persistent homology — a method that tracks how connected components and loops in the vorticity landscape are born and die as the field is systematically ‘flooded’ — the researchers converted persistence diagrams into persistence images and applied principal component analysis. The low-activity and high-activity regimes separated cleanly along the dominant principal component, with the transition occurring at the same critical activity identified by the SLE diagnostics and the vortex network analyses. Below the threshold, topological features had similar lifetimes, reflecting smooth, weakly structured flows; above it, the lifetime distributions broadened into long tails characteristic of heterogeneous, intermittent fields. Three independent lenses — nodal line geometry, vortex mechanics and field topology — all converge on the same critical point, establishing the transition as a robust, system-wide reorganization.

The implications reach well beyond soft matter laboratories. Because changes in flow organization in biological systems are tied to transport, mixing and force transmission, the identified threshold marks the point at which an active flow becomes coordinated across the entire system, both geometrically and mechanically. The work also connects active turbulence to a growing family of non-equilibrium systems in which conformal invariance has recently been spotted, including driven amorphous solids, water-wave turbulence and liquid-crystal interfaces, and it dovetails with theoretical efforts linking conformal symmetry, topology and non-equilibrium field theory. Open questions remain — most strikingly why the critical percolation of nodal lines and the rigidity percolation of vortex centres, distinct universality classes in equilibrium settings, coincide here. But the message is clear: fully developed active turbulence is not merely a disordered regime. It is a non-equilibrium critical state, and the boundary of that state can now be measured, in a microscope, with nothing more than the zeros of a vorticity field.

Subject of Research: The onset of fully developed active turbulence as an activity-driven non-equilibrium phase transition with critical percolation and rigidity statistics

Article Title: Fully developed active turbulence defined through a non-equilibrium phase transition

Article References: Bonn, L., Ma, T., Bantysh, O., Feng, W., Pedersen, M. C., Jing, G., Ignés-Mullol, J., Sagués, F., Araujo, N. A. M., & Doostmohammadi, A. (2026). Fully developed active turbulence defined through a non-equilibrium phase transition. Nature Physics. https://doi.org/10.1038/s41567-026-03408-y

Image Credits: AI Generated

DOI: 10.1038/s41567-026-03408-y

Keywords: active matter, active turbulence, phase transition, percolation, Schramm-Loewner evolution, conformal invariance, active nematics, bacterial suspensions, rigidity percolation, persistent homology, non-equilibrium physics, vorticity

The team, led by Nico Appold, Timon Citak, Auguste Palm and Jona Kayser, built a microbial therapy-mimicry assay around the budding yeast Saccharomyces cerevisiae. Populations were initiated from single, genetically tailored cells placed in a high-throughput arrayed colony assay, where each founder cell expanded into a compact, range-expanding colony. To generate a continual supply of trackable resistant mutants, the researchers engineered a stochastic, irreversible synthetic mutation system based on a hierarchical dual-recombinase switch. In the unmutated state, cells are thermosensitive: they proliferate at 30 degrees Celsius but arrest at 35 degrees. Upon switching, cells become thermoresistant and simultaneously change fluorescence colour, allowing resistant lineages to be identified and followed throughout colony growth. Treatment itself is delivered through programmable temperature shifts, giving the experimenters precise control over therapy onset, duration and pause.

Combining this assay with multi-day time-lapse fluorescence microscopy and automated temperature control, the researchers recorded population histories for up to 160 hours, spanning more than 100 generations. A custom image-analysis pipeline using machine learning-based segmentation extracted colony- and clone-level dynamics from the raw imaging data. Radial kymographs, which trace population structure along the direction of expansion, revealed two qualitatively distinct fates for resistant clones. Some escaped confinement as continually growing domes at the colony edge, but most remained trapped within the population bulk. This baseline phenomenology set the stage for the central question: what determines whether a bulk-born mutant escapes or stays confined?

Under continuous therapy, the answer proved to be strikingly spatial. Although the temperature shift was spatially homogeneous, mutant expansion showed pronounced spatiotemporal structure. The time at which a resistant mutant was first detected correlated strongly with its distance from the colony front, indicating that mutant growth was gated by a spatially varying growth potential within the colony. Individual mutant trajectories crept towards the colony edge until permanent escape occurred, and mutants originating further inward sometimes remained confined when a more forward lineage occupied the advancing front. At the colony level, this created a finite time window after therapy onset during which no mutant had yet escaped; as therapy continued, the cumulative number of escaped mutants rose steadily.

The existence of this delay suggested a therapeutic lever. If treatment were paused before any mutant reached the edge, the resumption of sensitive growth might re-establish a competitive barrier at the front. The researchers tested this with a 14-hour therapy pulse followed by a treatment holiday. Strikingly, many mutants that had expanded during the pulse stalled and remained confined within the colony bulk, with re-confinement often preceding the full recovery of sensitive expansion. Systematically varying pulse duration showed that shortening treatment strongly enhanced confinement: for pulses shorter than six hours, resistance escape was almost completely suppressed. The maximum safe pulse length proved more restrictive than continuous-therapy trajectories alone would suggest, because mutants continue advancing during the post-pulse regrowth lag.

To explain these observations mechanistically, the team constructed a stochastic simulation framework, a mechanistically minimal digital twin in which nutrient dynamics are directly accessible. Space is discretized into a two-dimensional grid of demes containing sensitive and resistant cells that proliferate at nutrient-dependent rates and disperse through growth-driven spreading. Competition is mediated solely through a shared, freely diffusing and consumable nutrient field, with no explicit local carrying capacity. Therapy is implemented as a modulation of sensitive growth that captures experimentally observed response kinetics, including on-delays and post-treatment lags. Despite its minimal structure, the model qualitatively reproduced the key experimental dynamics: bulk-born mutants released under therapy, and re-confinement when treatment pauses allowed sensitive growth to rebound.

The digital twin revealed the underlying resource logic. In a range-expanding population, growth and nutrient consumption generate a nutrient gradient along the expansion direction, and the advancing front continuously couples the colony edge to the high-nutrient side of this gradient. Under continuous therapy, suppressed sensitive growth reduces nutrient consumption, allowing nutrients to penetrate inward and expanding the growth-permitting region into the bulk. This releases previously confined resistant mutants and ultimately enables them to reach and escape at the colony edge. Pausing therapy reverses the process: renewed sensitive growth restores nutrient depletion in the bulk and reforms a competitive barrier of sensitive cells at the front, restoring spatial confinement.

With this mechanism in hand, the researchers scanned a large space of intermittent schedules, varying the durations of therapy-on and therapy-off intervals. Performance was quantified by time to progression, the time required for colony area to exceed a predefined threshold. Across schedule space, time to progression exhibited a pronounced ridge of optimal schedules separating two modes of failure: sensitive-dominated progression under too little treatment and resistant-dominated progression under too much. A sharp switch in the resistant fraction occurred near the optimum, which the authors describe as a dynamic phase-transition-like boundary in schedule space. Beyond the critical pulse length, therapy depresses front growth strongly enough that recovery during each pause is incomplete, producing a ratchet-like drift that progressively weakens confinement until resistant clones escape.

Guided by the simulations, the team tested the predicted sweet spot experimentally using pulse durations of four, 6.5 and nine hours with 18-hour pauses. The experiments confirmed a local optimum: time to progression peaked at 6.5-hour pulses, which significantly outperformed continuous therapy and both adjacent schedules, and the resistant fraction rose sharply near the transition. The 9-hour schedule reproduced the model-predicted cumulative decline in sensitive growth and surge in mutant escapes. As a proof of principle, the researchers also ran an adaptive therapy experiment in which treatment intervals were adjusted in real time based on measured growth rebound rather than fixed intervals. This closed-loop strategy slowed overall growth more than any fixed schedule, typically delaying progression beyond the experimental runtime, although resistant-population dynamics were more variable.

The study establishes resource-mediated spatial confinement as a central organizing principle of resistance evolution and offers a mechanistic foundation for spatially informed, evolution-based therapies. The authors suggest that growth rebound could serve as a clinically accessible measure of confinement potential, and that poorly vascularized tumours with steep resource gradients may be ideal candidates for such approaches, potentially enhanced by angiogenesis-targeting drugs. The findings may also explain why recent clinical trials of intermittent therapy failed to improve progression-free survival: the therapeutic sweet spot is narrow, and hitting it requires accounting for spatial resource dynamics that mean-field models ignore. The researchers caution that their yeast assay is deliberately reductionist, and that testing confinement-and-release dynamics in three-dimensional cancer organoids and matrix-producing biofilms will be essential before drawing clinical conclusions. Still, the message is clear: whether therapy fails may hinge on whether treatment shifts the resource gradient long enough for bulk-born mutants to permanently escape confinement.

Subject of Research: Spatial resource dynamics governing the emergence and escape of therapy-resistant mutants in structured microbial populations

Article Title: A microbial therapy-mimicry assay shows how spatial resource dynamics control resistance escape

Article References: A microbial therapy-mimicry assay shows how spatial resource dynamics control resistance escape. (n.d.). https://doi.org/10.1038/s41559-026-03178-z

Image Credits: AI Generated

DOI: 10.1038/s41559-026-03178-z

Keywords: therapy resistance, spatial evolution, nutrient gradients, intermittent therapy, adaptive therapy, yeast colonies, digital twin, biofilms, cancer evolution, experimental evolution, phase transition, range expansion

The inspiration comes directly from living cells. Biological ion channels are not rigid sieves; they are dynamic molecular machines that couple their local electrostatic environment to the hydration state of the interface, achieving selectivity and transport rates that approach the diffusion limit. Potassium channels, for example, use coordinated amino acid residues to strip the hydration shell from ions as they pass. Synthetic solid-state nanochannels have long tried to imitate this behavior by decorating rigid channel walls with stimuli-responsive molecules, converting molecular recognition events directly into measurable ionic currents. The problem has always been that these functionalizations are essentially two-dimensional, painting the sensing chemistry onto a flat surface where physiological salt can neutralize it.

The new platform, developed by Liu Shi, Genxi Li and colleagues, flips that geometry. Instead of modifying the channel surface, the team assembled a peptide-DNA hybrid hydrogel asymmetrically on the exterior of an anodic aluminum oxide membrane, creating a volumetric functional zone roughly 25 to 30 micrometers thick that acts as an active ion trap. The hydrogel is superhydrophilic and densely charged, so it pre-concentrates bulk ions through macroscopic Donnan enrichment while simultaneously generating a substantial Donnan potential. Because this charge reservoir occupies a volume orders of magnitude larger than the compressed Debye length, it keeps working even in the harshest ionic environments the body can supply.

The molecular architecture of the gate is a piece of careful supramolecular engineering. Single-stranded linker DNA is covalently anchored to the nanochannel surface, then a bridging strand and polyacrylamide conjugates are hybridized stepwise into the network. At the heart of the assembly sits a peptide-DNA complex cross-linker, synthesized through orthogonal thiol-maleimide coupling and strain-promoted alkyne-azide cycloaddition. The peptide backbone physically tethers the polymer-nucleic acid strands in close proximity, and this localized proximity effect entropically stabilizes the short DNA duplexes that hold the whole gel together. The elegance of the design is that the same tether that builds the network becomes its Achilles heel: a specific enzyme can cut it, and the entire structure falls apart on command.

That enzyme is Granzyme B, a serine protease released by cytotoxic T lymphocytes and a pivotal biomarker for gauging whether lung cancer patients are responding to immune checkpoint blockade therapy. When Granzyme B cleaves the peptide cross-linkers, the hydrogel undergoes a macroscopic gel-to-sol phase transition. Rheological measurements captured the collapse dramatically, with the storage modulus falling below the loss modulus as the elastic network vanished. Confocal microscopy showed fluorescently labeled gels fading after enzymatic treatment, while spectroscopy confirmed the loss of amide and hydrogen-bonding signatures. The gate does not merely weaken; it switches off.

The shutdown is synergistic, and that synergy is where the signal amplification comes from. As the gel disassembles, its volumetric charge reservoir dissipates, with the effective surface charge density dropping from -5.26 to -0.92 millivolts per square centimeter, an 82.5 percent loss in charge capacity. At the same time, the interface loses its superhydrophilicity, with the water contact angle rising from about 7.6 degrees to 39.0 degrees. Finite-element simulations governed by the Poisson-Nernst-Planck equations, fed with these experimentally measured parameters, showed the cation enrichment zone vanishing and the energy barrier for ion entry soaring. In a two-compartment electrochemical cell, the device swung from a high-current ON state of roughly 17.8 microamperes to an OFF state of about 3.07 microamperes, a gating ratio of approximately 5.8.

The comparison with a conventional two-dimensional control is what makes the result compelling. A monolayer of the same peptide chemistry on the channel surface showed only minor changes in wettability and charge after cleavage, and its sensing performance suffered accordingly, with a constrained dynamic range and reduced linearity. More tellingly, when the researchers varied the background ionic strength from 10 to 200 millimolar, the 2D device’s gating ratio collapsed sharply around 50 millimolar, exactly where Debye screening takes over. The 3D hydrogel platform, by contrast, maintained robust signal modulation all the way to 200 millimolar. In a physiological 150 millimolar buffer, the device still achieved a limit of detection of 133.60 femtomolar, while in low-salt conditions it reached an extraordinary 0.830 femtomolar across a range spanning six orders of magnitude.

The modularity of the building blocks opened a further, almost playful dimension: molecular computing. By incorporating cross-linkers responsive to both Granzyme B and matrix metalloproteinase 2 into a single hydrogel, the team built a cascaded logic circuit with two parallel INHIBIT sub-circuits feeding an OR gate. Each enzyme can independently trigger the phase disassembly and generate a current response, but a specific inhibitor for each enzyme vetoes the process. The device executed a full truth table of Boolean operations on biochemical inputs, supported by molecular docking simulations of the enzyme-inhibitor pairs. It is a small demonstration, but it points toward sensors that do not merely detect a molecule but compute a diagnosis from a panel of interacting biological signals.

Robustness in messy biological fluids proved equally impressive. The intact hydrogel doubles as a physical shield against non-specific fouling, and the sensor held its performance in 10 percent fetal bovine serum and 10 percent human serum, showing strict selectivity against a panel of interfering proteins. The device survived five regeneration cycles with consistent current switching, showed negligible degradation over 15 days of storage, and achieved batch-to-batch reproducibility with a relative standard deviation of just 1.62 percent. These are the unglamorous metrics that decide whether a laboratory curiosity can ever become a clinical instrument, and the platform passed them.

The clinical proof of concept is the most striking part of the story. Working with serum samples from healthy donors and lung cancer patients collected before and after immune checkpoint blockade therapy, under a protocol approved by the Medical Ethics Committee of Shanghai Pulmonary Hospital, the team measured Granzyme B directly in unpurified specimens. Healthy individuals averaged around 0.8 picomolar, while pre-treatment patients showed suppressed levels of roughly 0.3 to 0.5 picomolar, reflecting the immunosuppressive microenvironment of advanced malignancies. After immunotherapy, concentrations surged to 2.0 to 2.5 picomolar, signaling restored T-cell cytotoxicity. Benchmarked against a commercial ELISA, the sensor achieved a correlation coefficient of 0.962, a negligible mean bias of 0.0423 picomolar by Bland-Altman analysis, and an area under the ROC curve of 0.980 for distinguishing healthy from pre-treatment patients, with near-perfect discrimination of therapeutic response. The researchers acknowledge that translation will require packing the electrochemistry into automated microfluidic cassettes and expanding the logic gates to wider biomarker panels, but the core demonstration stands: by thinking in three dimensions, a dissolving gel has done what flat chemistry could not, carrying ultrasensitive nanochannel sensing out of the buffer and into the blood.

Subject of Research: A three-dimensional hydrogel soft-gating strategy for solid-state nanochannel biosensors that circumvents Debye screening to enable ultrasensitive detection of Granzyme B for immunotherapy monitoring.

Article Title: Hydrogel Phase Transition‐Driven Soft Gating Circumvents Debye Screening for Advanced Biosensing

Article References: Shi, L., Zhang, Z., Li, B., Gao, Y., Zhang, R., Mu, Z., Ni, J., Bo, B., & Li, G. (2026). Hydrogel Phase Transition‐Driven Soft Gating Circumvents Debye Screening for Advanced Biosensing. Advanced Science, Article e78049. https://doi.org/10.1002/advs.78049

Image Credits: AI Generated

DOI: 10.1002/advs.78049

Keywords: nanochannel biosensing, hydrogel, Debye screening, Donnan enrichment, Granzyme B, peptide-DNA hybrid, iontronics, immune checkpoint blockade, lung cancer, biocomputing, phase transition, clinical diagnostics