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Evidence of elusive high-energy gravitons in quantum Hall systems

Electrons, negatively charged particles, sometimes coordinate their movements in ways that produce certain collective excitations referred to as quasiparticles. One case in which this occurs is the quantum Hall effect, a phenomenon that emerges when electrons are confined to a very thin layer, cooled to temperatures around 0 kelvin and exposed to a very strong magnetic field.

A framework called parton theory hypothesized the existence of emergent partons (i.e., quark-like quasiparticles in condensed matter physics that should not be confused with quarks and gluons in particle physics) to explain the collective excitations of quantum Hall states.

Recent geometric theoretical frameworks also suggest that small fluctuations in a system’s quantum metric (i.e., a quantity describing the ‘shape’ of a quantum state) produce collective spin-2 excitations referred to as chiral gravitons.

Baseline tool could separate alien life signals from geology on ocean worlds

When it comes to the search for life elsewhere in the universe, methane and other chemical compounds are seen as signs of biology because they are often produced by living microbes. However, scientists can be misled because certain geological processes can produce chemical signatures identical to those of living organisms.

To help identify true biological signals and reduce the risk of false detections, researchers have developed a framework that models what a planet’s chemistry looks like without life.

Their research is published in the journal Nature Astronomy.

Saturn-ring-like laser emission from chiral polymeric microspheres

Controlling light within microscopic spaces is crucial for next-generation optical devices such as photonic integrated circuits and localized sensors. Microspheres formed of luminescent π-conjugated polymers act as optical resonators that confine and amplify light via whispering gallery modes (WGMs), and they are promising candidates for microscale organic lasers and photonic applications. However, conventional microsphere resonators are geometrically isotropic and emit isotropic light, making directional control of emissions challenging.

In a new study published in the Journal of the American Chemical Society, researchers from the University of Tsukuba show that microspheres formed through the self-assembly of chiral π-conjugated polymers possess a characteristic twisted bipolar molecular configuration, enabling angle-selective optical resonance and laser oscillation with distinct azimuthal directionality. Using polarization-dependent photoluminescence imaging, the research team directly visualized a vortex-like (swirling) arrangement formed by the polymer main chains on the spherical surface.

Furthermore, this vortex-like surface molecular orientation induces an azimuth-dependent refractive-index distribution along the light propagation path, resulting in angle-dependent WGM resonance wavelengths and spatially localized emission. Consequently, the microspheres exhibit directional laser oscillation, preferentially emitting amplified light along a specific azimuthal direction. The resulting emission pattern is analogous to Saturn’s rings.

Metallic rutile oxides break the rules of cooling

Physicists have long puzzled over a strange contradiction inside a family of minerals called rutile oxides. These materials all share the same crystal structure—but while some of them, like titanium dioxide, are firmly insulating, others, like ruthenium dioxide, conduct electricity like a metal. So far, physicists have had little idea of why this happens.

In a new study published in Physical Review B, researchers led by Kaushik Sen at the Indian Institute of Technology Delhi traced the answer back to phonons: the tiny vibrations that ripple through a material’s atomic lattice.

Their discovery reveals that metallic rutile oxides develop a fundamentally different relationship between electrons and phonons as they cool—settling a long-running scientific dispute along the way.

How approaching sounds can warp your perception of time

Everyone’s perception of time is unique. It is a subjective experience shaped by factors such as age, emotions, memory and environmental contexts. And it may also be influenced by background noise, as scientists have demonstrated in a paper published in the journal Scientific Reports.

Previous research has shown that approaching noise can stretch our perception of time. But in this paper, researchers in Japan discovered that even when people were concentrating on a different sound, moving sounds in the background still changed their sense of time.

Quantum computers model nine fusion fuel material configurations for first time

A team of scientists from Oak Ridge National Laboratory, Cleveland Clinic and IBM has calculated nine molecular configurations of a promising material to produce fuel for fusion energy—the first known instance of such computations on quantum computers.

Such calculations, demonstrated in a new paper published on the arXiv preprint server, are computationally challenging for classical computers to scale when working alone. They are a fundamental step toward optimizing the production and extraction of tritium—an extremely rare material in nature that is necessary to produce fusion energy with most of the proposed machines. Ensuring adequate supplies of tritium has long been a barrier to realizing the promise of clean, abundant energy from fusion power plants, and solving this issue is a key objective of the U.S. Department of Energy’s Genesis Mission.

Quantum computers are well-suited to computing the atomic-level chemistry of a liquid salt that contains fluorine, lithium and beryllium (FLiBe), one of the leading candidate materials for extracting tritium fuel in fusion reactors. To compute different configurations of clusters of FLiBe, the team used the same quantum-centric supercomputing techniques now being applied to 12,635-atom protein simulations with Cleveland Clinic. These methods can calculate the quantum behavior of electrons in complex materials, complementing and enhancing the capabilities of classical supercomputers and algorithms.

Magnetic octupole model captures domain-wall motion in noncollinear antiferromagnets

Researchers from The Grainger College of Engineering at the University of Illinois Urbana-Champaign have developed the first magnetic multipole-based micromagnetic model for antiferromagnets. Published in Applied Physics Reviews, their generalized framework provides a theoretical and computational foundation for designing future spintronic devices made with antiferromagnetic materials.

Unlike traditional electronics, which rely on an electron’s charge, spin electronics harnesses an electron’s magnetic orientation (spin). In recent years, materials science researchers have identified antiferromagnets as a promising material for future spintronic devices because of their ultrafast spin dynamics and stability under external magnetic fields.

But before these materials can be implemented in practical devices, researchers need robust models that decipher their complex, nonuniform movements. Although micromagnetic simulations have been widely used to study spin dynamics in ferromagnets, a comparable framework had yet to be fully established for antiferromagnets, whose spin structure is more difficult to control. However, some types of antiferromagnets—such as noncollinear antiferromagnets—have a unique rotating structure that is more easily manipulated.

Day-night ocean warming helps explain why El Niño outpaces La Niña in models

Researchers have long known that there is an asymmetry in the El Niño-Southern Oscillation (ENSO), the confluence of wind and water currents that creates warm El Niño events and cooler La Niña events. Large-scale climate models tend to underrepresent this asymmetry for reasons that are still not fully understood. Better modeling of the mechanisms that make El Niño events warmer could both provide insight into Earth’s climate system and improve future ENSO predictions.

Previous studies of the asymmetry have looked at large-scale processes such as wind stress responses and thermal advection but haven’t fully answered the question. In a new approach, Yang and team examined how variations in sea surface temperature from day to night affect ENSO asymmetry, approaching the problem at a much smaller scale. The findings are published in the journal Geophysical Research Letters.

Comparing 35 Coupled Model Intercomparison Project Phase 6 (CMIP6) models, the researchers found that models with larger diurnal amplitudes (DA) for temperature better captured the ENSO asymmetry. Looking deeper with targeted model experiments, they found that a major driver of this mechanism is opposing daily mean sea surface temperature anomaly responses in the central and eastern Pacific. This east–west temperature difference causes the ocean to warm unevenly over months or longer. As a result, El Niño warms the ocean more than La Niña cools it.

Pressure unlocks 3D superconductivity in tantalum disulfide at triple the temperature

Superconductors have long been considered a promising technology for the energy systems of the future. They can conduct electricity without resistance, thus eliminating both conduction losses and waste heat. Up to now, however, superconductors have only been applied in special cases, as in the immensely powerful magnet coils of particle accelerators such as the Large Hadron Collider at CERN. This is because superconductors must be well cooled, down to extremely low temperatures for some materials.

In the future, novel materials with special quantum properties are expected to make superconductivity possible at less frosty and more easily achievable subzero temperatures. A research team led by Zurab Guguchia at the Paul Scherrer Institute PSI has now provided the first comprehensive characterization of such a quantum material. This should contribute to a detailed understanding of these processes and facilitate the search for technologically usable superconductors. The results are published in the journal Nature Communications.

“Currently, research is being conducted worldwide on novel, unconventional superconductors that exhibit robust superconductivity even at higher temperatures or in strong external magnetic fields,” Guguchia says. The physicist is a research group leader in the PSI Center for Neutron and Muon Sciences and works with his team on the materials of the future.

Quantum vacuum could help break molecular bonds with less energy, simulations suggest

A team of researchers led by Felipe Herrera, a professor at the University of Santiago and a researcher at the Millennium Institute for Research in Optics (MIRO), has identified a quantum phenomenon that enables chemical bonds to be broken using significantly less energy than is normally required.

The findings, published in Physical Review Letters under the title “Enhancing Infrared-Laser Dissociation of Molecules with the Electromagnetic Vacuum,” demonstrate that by using infrared light, the natural fluctuations present in the electromagnetic vacuum can promote molecular dissociation when molecules are confined within specially designed nanometer-scale structures known as nanocavities.

Although we often think of a vacuum as completely empty space, quantum physics shows that it is filled with tiny energy fluctuations. The researchers discovered that these fluctuations can be amplified inside a nanocavity, altering molecular vibrations and making it easier for an infrared laser to break chemical bonds.

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