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Category: particle physics – Page 15

Going beyond simple models of neural networks: Extended mean-field theory offers a better approach

Physics is most readily applied to relatively simple systems: a pendulum, two electrons colliding or the structure of the solar system. But when systems become complicated—when many particles interact with one another, in condensed matter systems such as gases and fluids or in the cosmology of the early universe—simplifications can be made using a technique called classical or extended mean-field theory.

A research group from Princeton University, led by lead author Luca Di Carlo, has applied extended mean-field theory to networks of biological neurons. Their work is published in the journal Physical Review Letters. They found that the simplest versions of mean-field theory failed to accurately describe the activity of these networks, but an enhanced version was able to do so.

Observing the vibrations of neighboring atoms with an atomic-scale double slit

Efficiently controlling heat generation has become a major challenge as the semiconductors used in smartphones, computers and similar devices have become higher-performing and more miniaturized. The way heat is transmitted is determined by the vibration of the atoms that constitute a material, but it is not easy to directly examine, at the atomic scale, how neighboring atoms vibrate in coordination with one another.

A research group made up of Director and Professor Naoya Shibata, JSPS Research Fellow Koudai Tabata, Associate Professor Taketo Seki and Project Associate Professor Ryo Ishikawa, all of the Institute of Engineering Innovation, School of Engineering, The University of Tokyo, has succeeded in an atomic-scale double-slit experiment that treats neighboring atoms as “two slits” and demonstrates that it is possible to read out the vibration of atoms from the fringe pattern formed by electrons. Their paper is published in the journal Nature.

The double-slit experiment makes use of a phenomenon in which waves passing through two narrow slits overlap and create a pattern of bright and dark fringes. Since the British physicist Thomas Young first performed it using light in the early 19th century, it (Young’s experiment) has been known as a fundamental experiment demonstrating the wave nature of light. If this experiment could be reduced to the atomic scale inside a material, it would allow direct investigation of the arrangement and motion of atoms at the level of a single atomic bond, but an atomic-scale double-slit experiment of this kind has never been realized.

Tiny atomic changes could lead to smarter wireless technology

Researchers at Queen Mary University of London have shown that making extremely small changes to the structure of a material can dramatically improve its ability to respond to electrical signals. Published recently in Science Advances, the breakthrough could help create a new generation of wireless devices that can change frequency on demand, making communication systems more flexible and energy efficient.

The team focused on a ceramic material called strontium tantalate. By replacing a small number of atoms with slightly smaller calcium atoms, they created tiny distortions in the material’s structure. Although these changes occur at the atomic scale, they have a major effect on how the material behaves.

Physicists Hunted a Mysterious Particle — and Found Two Unexpected Structures Instead

A first attempt to produce a mysterious strangeonium state using a photon beam yielded important and unexpected results.

Physicists have spent decades trying to organize the growing collection of subatomic particles, yet some of the most unusual discoveries still resist simple classification. At the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility, researchers have now detected evidence for two unexpected structures that could help clarify this increasingly complicated landscape.

The signals may shed light on a puzzling class of particles called XYZ states. These objects do not fit comfortably within the conventional picture of particles built from quarks, the elementary constituents of matter. For the first time at Jefferson Lab, two such signals were observed when a beam of high-energy photons struck a proton target.

Simulations reveal asymmetric diffusion of magnetic skyrmions through an off-center gate

Diffusion is a fundamental natural phenomenon that can be observed across a wide range of length and time scales. It plays a key role in many fields, including physics, biology and economics. In particular, asymmetric or directional diffusion of particle systems has attracted growing interest for practical applications, including the development of unconventional artificial intelligence (AI) hardware, where it could enable nonlinear, geometry-controlled information processing.

Magnetic skyrmions are topological spin textures that can behave as particle-like objects with chiral dynamics. Recent reports have shown that even tiny thermal fluctuations can drive effective diffusion of skyrmions in ultrathin magnetic films and layered heterostructures. Some experiments have also revealed a topology-dependent sideways, wall-guided motion known as the Brownian gyromotion of skyrmions when they interact in a confined space.

Magnetic skyrmions can also exhibit exotic dynamic behaviors that cannot be reproduced by common particles. Their diffusive properties have immense potential in novel information-processing applications. However, these properties, especially in structured environments, remain largely unexplored.

Vacuum-fluctuation-enhanced superconductivity demonstrated for the first time

In a study published in Nature on Aug. 19, a research team has enhanced superconductivity through vacuum fluctuations for the first time. The achievement marks a significant advance in controlling quantum states of matter.

Space free of matter is not truly empty. A vacuum is not a void. In quantum electrodynamics, the Heisenberg uncertainty principle implies that, even in the ground state, there is irreducible activity, with the continual creation and annihilation of virtual particles.

Thus, a vacuum contains a dynamic “sea” of quantum fluctuations. Several celebrated phenomena, including the Lamb shift, spontaneous emission and the Casimir effect, provide compelling experimental evidence for their existence.

Molecular trick opens the door to a new generation of glass

Researchers at TU Dortmund University, Paderborn University, the University of Duisburg-Essen, and the University of Oxford have developed a new method for selectively modifying the internal structure of specific types of glass. The study, published in the journal Nature Materials, shows how adding an organic molecule during melting causes the chemical bonds in the material to rearrange. The process reduces the required processing temperature, prevents the substance from decomposing, and allows the magnetic and optical properties to be precisely tuned. These specialized glasses are used, among other things, in gas storage, batteries, optical applications and catalysis.

“We have found a way to chemically modify the structure of glasses derived from so-called metal-organic framework compounds—or MOFs for short—right during the manufacturing process,” explains Dr. Sebastian Henke from TU Dortmund University, who led the study.

To achieve this, the experts used 1,10-phenanthroline. The molecule lowers the melting point while simultaneously altering how the metal atoms in the glass are bonded together. The major advantage is that researchers could develop glasses with magnetic or light-emitting properties that were previously impossible to achieve without destroying the material through extreme heat.

New free-space optical link adds a wireless component to the nation’s longest quantum network

There’s a new lighthouse on Long Island. But instead of shining light to guide ships through waterways, this one transmits and receives particles of light that carry quantum information. Perched atop a seven-story building at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, the “Quantum Lighthouse” is a key pillar of the free-space optical (FSO) link spanning Brookhaven Lab, the State University of New York at Stony Brook (Stony Brook University) and Yale University.

“An FSO link is analogous to the wireless technology that allowed today’s classical internet to expand beyond wired connections to orbiting satellites, as well as our cellphones,” said Justine Haupt, Brookhaven Lab’s lead scientist on the cross-institutional FSO link project. “It’s one of the key technologies needed to make a quantum internet truly useful.”

This FSO link—the first permanent one of its kind—adds a wireless component to the nation’s longest quantum network, which spans 161 miles (259 kilometers) across Long Island and the New York metropolitan area.

Mapping thorium’s preferred sites could pave the way for nuclear clocks

For decades, physicists have used a technique called Mössbauer spectroscopy to peer inside solid materials, revealing fine details of their surroundings by studying how their atomic nuclei absorb and re-emit gamma rays.

Through new research published in Science, a team led by Takahiro Hiraki at Okayama University has pushed this approach into entirely new territory, using visible-adjacent light instead of gamma rays to study the nuclei of thorium-229 atoms. The advance offers a promising new route toward nuclear clocks, devices that could one day keep time more precisely than anything built before.

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