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Category: particle physics – Page 21

Physicists create Bose–Einstein condensate from ultracold polar molecules

Bose–Einstein condensates are states of matter that form when particles called bosons are cooled to temperatures that are only a fraction of a degree above absolute zero (i.e., 0 Kelvin [-460°F]). In these states, particles occupy the same quantum state and exhibit interesting collective behaviors, essentially behaving as if they were a single “super-particle.”

So far, physicists have primarily created Bose–Einstein condensates using atoms. The first realization of these states with molecules was just over two decades ago, in 2003.

Producing Bose–Einstein condensates with ultracold polar molecules, cooled molecules in which positive and negative charges are separate, has proved particularly challenging. This is partly due to chemical reactions that can cause a loss of these molecules while they are being cooled.

Finally! After 20 Years, Major Quantum Entanglement Theory Has Been Experimentally Confirmed

Quantum mechanics is so odd that even the visionary genius who described the secrets of the Universe seemed to dismiss certain aspects as eerie.

“Spooky action at a distance” is how Albert Einstein described quantum entanglement, a weird connection between particles that classical physics cannot explain.

From our classical perspective, it seems to allow instantaneous communication, thereby breaking the speed of light and garnering Einstein’s ire.

Strain turns non-chiral crystals left- or right-handed on demand

Mechanical strain is one of the most common tools used to tailor the properties of materials. In piezoelectric materials, stretching or compressing a crystal generates an electrical polarization. In piezomagnetic materials, it induces magnetization. Researchers at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) and the University of Oxford have now discovered that mechanical strain also induces chirality in non-chiral crystals, opening a new direction to control this property on demand and potentially imprint chiral electronic properties. This work has just been published in Nature.

Chirality is an important property of matter. It is defined as a property of objects that cannot be superimposed on their mirror images through any combination of rotations or translations, much like distinct left and right hands. In chiral crystals, the spatial arrangement of atoms gives rise to a specific handedness, with the crystal structure twisting along one propagation direction in a way similar to a screw.

As a consequence, propagation in one direction, for example, of an electrical current, may experience different resistance than propagation in the opposite direction. This effect also influences certain chemical reactions and biological processes, which select for one specific handedness. In this sense, the ability to control chirality on demand, turning a right-handed structure into a left-handed one, is highly desirable.

New research shows how ‘hot electrons’ can reshape metals in billionths of a second

Researchers at The University of Manchester have revealed how intense electronic excitation can trigger rapid structural changes in metals—without heating the atomic lattice—offering new insight into ultrafast materials behavior.

When metals are exposed to powerful laser pulses, their electrons can heat up almost instantly, reaching extreme temperatures while the atoms themselves remain relatively cold. This study shows that, under these conditions, the behavior of the material is driven not by heat in the traditional sense, but by changes in the electronic system.

Published in Physical Review Materials, the research, led by Dr. Sam Azadi, demonstrates that this electronic “reheating” alone can cause metals to switch between different crystal structures in a fraction of a picosecond.

Trembling Photons in Non-Abelian Electric Fields

A ring of optical fiber can be made to host phenomena that originated in the realm of high-energy physics.

In non-Abelian gauge theories, particles interact with each other; operation order matters; and a so-called gauge symmetry ensures the invariance of physical laws under local transformations via fields mediated by photons, gluons, and the W and Z bosons. Such theories describe the strong and weak forces; provide the mathematical backbone of the standard model; and underpin efforts to understand the early Universe, quantum gravity, and exotic topological phases of matter. For decades, subjecting these theories to direct experimental scrutiny often meant resorting to enormous particle accelerators. Recently, an experimental approach known as photonic synthetic dimensions has offered a tabletop alternative. Applications of the approach have already realized a non-Abelian magnetic field [1]. Now Shu Yang of the University of Hong Kong and his colleagues have synthesized the corresponding non-Abelian electric field [2].

Water’s local asymmetry drives proton hopping between molecules, simulations reveal

Complex simulations—the most intricate of their kind to date—carried out by an international research team led by scientists at Heidelberg University’s Institute for Physical Chemistry, have revealed how water governs the way protons move through it. Using their modeling, researchers from Cambridge (U.K.), Bochum, Dijon (France) and Heidelberg were able to trace, in full quantum detail, the movements of a proton shared among six water molecules. At its core, the work addresses how a proton moves through water: not as a single particle drifting along, but by “hopping” from one molecule to the next.

This “hopping” motion has been known since the 19th century. When an acid dissolves in water, the released proton—a positively charged hydrogen ion—does not remain bound to a single water molecule. It is highly mobile and constantly jumps from one molecule to the next.

New thermodynamic framework explains pressure and edge currents in spinning active particles

Physicists from Heinrich Heine University Düsseldorf (HHU), the Technical University of Darmstadt, Sapienza University in Rome and the University of Camerino (both in Italy) have calculated the fundamental laws of thermodynamics for a gas composed of spinning particles. In the scientific journal Proceedings of the National Academy of Sciences (PNAS), they demonstrate that the pressure of this gas is similar to that of a normal gas but at an elevated temperature. In addition, localized surface currents arise that can be used for targeted particle transport.

The so-called ideal gas law is one of the fundamentals of thermodynamics and states that the pressure of a gas is proportional to its density and temperature. From a microscopic perspective, pressure is the average force per unit area exerted by incoming particles on impact and reflection. At a higher temperature, the particles move more quickly and therefore exert greater pressure on impact.

A research team led by Dr. Hartmut Löwen from the Institute for Theoretical Physics II at HHU asked whether the ideal gas law also applies to self-propelled, so-called “active” particles or whether the nonequilibrium state results in significant differences. In addition to the physicists in Düsseldorf, colleagues from Rome, Camerino and Darmstadt were also involved.

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