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Category: particle physics – Page 12

Spontaneous emission behaves contrary to predictions in photonic time crystals

A new study reveals that spontaneous emission, a key phenomenon in the interaction between light and atoms, manifests in a new form within a photonic time crystal. This research, led by a KAIST team, not only overturns existing theory but further predicts a novel phenomenon: spontaneous emission excitation. The findings are published in the journal Physical Review Letters.

Professor Bumki Min’s research team from the KAIST Department of Physics, in collaboration with Professor Jonghwa Shin of the Department of Materials Science and Engineering, Professor Wonju Jeon of the Department of Mechanical Engineering, Professor Gil Young Cho of the Department of Physics, and researchers from IBS, UC Berkeley, and the Hong Kong University of Science and Technology, announced that they have proven that the decay rate in a photonic time crystal is, on the contrary, enhanced rather than being “extinguished,” as suggested by a paper published in Science in 2022. Furthermore, they predicted a new process—spontaneous emission excitation—where an atom transitions from its to an while simultaneously emitting a photon.

Spontaneous emission is the process by which an atom intrinsically emits a photon and is fundamental to quantum optics and photonic device research. Until now, control over spontaneous emission has been achieved by designing spatial structures like resonators or . However, the advent of photonic time crystals, which periodically modulate the refractive index of a medium over time, has drawn attention to the potential for control along the time axis.

Parallel atom-photon entanglement paves way for future quantum networking

A new platform developed by Illinois Grainger engineers demonstrates the utility of a ytterbium-171 atom array in quantum networking. Their work represents a key step toward long-distance quantum communication.

Researchers from The Grainger College of Engineering at the University of Illinois Urbana-Champaign have introduced a scalable platform for quantum networking with a ytterbium-171 array.

Their work, published in Nature Physics, represents a major step toward larger quantum networks and has promising implications for modular quantum computation.

Extreme pressure pushes honeycomb crystal toward quantum spin liquid, hinting at new qubit designs

The future of computing lies in the surprising world of quantum physics, where the rules are much different from the ones that power today’s devices. Quantum computers promise to tackle problems too complex for even the fastest supercomputers running on silicon chips. To make this vision real, scientists around the world are searching for new quantum materials with unusual, almost otherworldly properties.

One of the more intriguing candidates is called a quantum spin liquid—a state of matter where electron spins never settle down, even at the coldest temperatures in the universe. To date, however, preparing such a quantum state in a lab has proven stubbornly elusive. In a collaborative project with multiple institutions, scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory now report coming tantalizingly closer.

As explained by Argonne Senior Physicist and Group Leader Daniel Haskel, in these materials, it’s not atoms that stay fluid as in an ordinary liquid, but the tiny magnetic orientations—or spins—of electrons. Each spin wants to “get along” with its neighbors by aligning in a way that keeps everyone content. But when the spins are pushed closer together under pressure, satisfying every neighbor becomes impossible.

Nanoscale slots enable room-temperature hybrid states of matter in perovskite

Atoms in crystalline solids sometimes vibrate in unison, giving rise to emergent phenomena known as phonons. Because these collective vibrations set the pace for how heat and energy move through materials, they play a central role in devices that capture or emit light, like solar cells and LEDs.

Collective Bloch oscillations observed in 1D Bose gas system

Bloch oscillations are periodic oscillations of quantum particles in a repeating energy “landscape” (e.g., a crystal lattice) that are subjected to a constant force. These particle motions have been the focus of numerous physics studies, as they are intriguing quantum effects that are not predicted by classical mechanics theories.

Probing Bloch oscillations experimentally could thus yield new insight into the fundamental properties of quantum matter. So far, they have been primarily studied in individual particles or two-particle systems, as opposed to quantum many-body systems comprised of several particles.

Researchers at CNRS-ENS-PSL University and Sorbonne University report the observation of collective Bloch oscillations in a one-dimensional (1D) Bose gas, a quantum fluid comprised of bosons, which are particles that can occupy the same quantum state.

Core electron bonding may not always require extreme pressure, study finds

You probably learned in high school chemistry class that core electrons don’t participate in chemical bonding.

They’re thought to be too deep inside an atom and close to the nucleus to meaningfully interact with the of other atoms, leaving the outer valence electrons to get all the glory in textbooks.

The actual science is more complicated, as some elements’ core electrons are theorized to activate when squeezed hard enough, like at the pressure levels found deep inside Earth.

Criticality in Nature’s Strongest Force

Experiments at the Relativistic Heavy Ion Collider give the first hints of a critical point in the hot quark–gluon “soup” that is thought to have pervaded the infant Universe.

The strongest force of nature—the one holding nuclear matter together—is described by the theory of quantum chromodynamics (QCD). The fundamental particles of QCD are quarks and gluons, which are normally bound within composite particles called hadrons—the most well-known of which are protons and neutrons. Only at extreme temperatures around 1012 K (a million times hotter than the core of the Sun) can quarks and gluons become deconfined, leading to a new phase of matter called the quark–gluon plasma. At vanishing densities, the transition between confined hadrons and the quark–gluon plasma is known to be ill-defined—happening across a wide range of temperatures rather than at a specific temperature. But theory predicts that at large densities and moderately high temperatures, a critical point exists, where the “fuzziness” disappears and a clear distinction can be made between the gas-like hadrons and the liquid-like quark–gluon mix [1–3].

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