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Category: particle physics – Page 243

Electronic pathways may enhance collective atomic vibrations’ magnetism

Materials with enhanced thermal conductivity are critical for the development of advanced devices to support applications in communications, clean energy and aerospace. But in order to engineer materials with this property, scientists need to understand how phonons, or quantum units of the vibration of atoms, behave in a particular substance.

“Phonons are quite important for studying new because they govern several such as thermal conductivity and carrier properties,” said Fuyang Tay, a graduate student in applied physics working with the Rice Advanced Magnet with Broadband Optics (RAMBO), a tabletop spectrometer in Junichiro Kono’s laboratory at Rice University. “For example, it is widely accepted that superconductivity arises from electron–phonon interactions.

Recently, there has been growing interest in the carried by phonon modes that show circular motion, also known as chiral . But the mechanisms that can lead to a large phonon magnetic moment are not well understood.

Q&A: Bringing virtual reality to nuclear and particle physics

Virtual reality, or VR, is not just for fun-filled video games and other visual entertainment. This technology, involving a computer-generated environment with objects that seem real, has found many scientific and educational applications as well.

Sean Preins, a doctoral student in the Department of Physics and Astronomy at the University of California, Riverside, has created a VR application called VIRTUE, for “Virtual Interactive Reality Toolkit for Understanding the EIC,” that is a game changer in how particle and nuclear physics data can be seen.

Made publicly available on Christmas Day, VIRTUE can be used to visualize experiments and simulated data from the upcoming Electron-Ion Collider, or EIC, a planned major new nuclear physics research facility at Brookhaven National Lab in Upton, New York. EIC will explore mysteries of the “strong force” that binds the atomic nucleus together. Electrons and ions, sped up to almost the speed of light, will collide with one another in the EIC.

New ALICE measurements shed light on the dynamics of charm and beauty particles in quark-gluon plasma

When two lead ions collide at the Large Hadron Collider (LHC), they produce an extremely hot and dense state of matter in which quarks and gluons are not confined inside composite particles called hadrons. This fireball of particles—known as quark–gluon plasma and believed to have filled the universe in the first few millionths of a second after the Big Bang—expands and cools down rapidly. The quarks and gluons then transform back into hadrons, which fly out of the collision zone towards particle detectors.

In collisions where the two do not collide head on, the overlap region between the ions has an elliptic shape that leaves an imprint on the flow of hadrons. Measurements of such elliptic flow provide a powerful way to study quark–gluon plasma. In a recent paper posted to the arXiv preprint server, the ALICE collaboration reported a new measurement of the elliptic flow of hadrons containing heavy , which are particularly powerful probes of the plasma.

Unlike the and light quarks that make up the bulk of the quark–gluon plasma created in heavy-ion collisions, heavy charm and beauty quarks are produced in the initial stages of the collisions, before the plasma forms. They therefore interact with the plasma throughout its entire evolution, from its expansion and cooling to its transformation into hadrons.

Riding the Cosmic Wave: How Plasma Instability Is Changing Our View of the Universe

Scientists from the Leibniz Institute for Astrophysics Potsdam (AIP) have discovered a new plasma instability that promises to revolutionize our understanding of the origin of cosmic rays and their dynamic impact on galaxies.

At the beginning of the last century, Victor Hess discovered a new phenomenon called cosmic rays that later on earned him the Nobel prize. He conducted high-altitude balloon flights to find that the Earth’s atmosphere is not ionized by the radioactivity of the ground. Instead, he confirmed that the origin of ionization was extra-terrestrial. Subsequently, it was determined that cosmic “rays” consist of charged particles from outer space flying close to the speed of light rather than radiation. However, the name “cosmic rays” outlasted these findings.

Recent advances in cosmic ray research.

Extending the uncertainty principle by using an unbounded operator

A study published in the journal Physical Review Letters by researchers in Japan solves a long-standing problem in quantum physics by redefining the uncertainty principle.

Werner Heisenberg’s uncertainty principle is a key and surprising feature of , and he can thank his hay fever for it. Miserable in Berlin in the summer of 1925, the young German physicist vacationed on the remote, rocky island of Helgoland, in the North Sea off the northern German coast. His allergies improved, and he was able to continue his work trying to understand the intricacies of Bohr’s model of the atom, developing tables of internal atomic properties, such as energy, position and momentum.

When he returned to Göttingen, his advisor, Max Born, recognized these tables could each be formed into a matrix—essentially a two-dimensional table of values. Together with the 22-year-old Pasqual Jordan, they refined their work into matrix mechanics—the first successful theory of quantum mechanics—the physical laws that describe tiny objects like atoms and electrons.

Embedding nanodiamonds in polymer can advance quantum computing and biological studies

A nitrogen-vacancy (NV) center is a defect in the crystal structure of diamond, where a nitrogen atom replaces a carbon atom in the diamond lattice and a neighboring site in the lattice is vacant. This and other fluorescent defects in diamond, known as color centers, have attracted researchers’ attention owing to their quantum properties, such as single-photon emission at room temperature and with long coherence time. Their many applications include quantum information encoding and processing, and cell marking in biological studies.

Microfabrication in diamond is technically difficult, and nanodiamonds with color centers have been embedded in custom-designed structures as a way of integrating these quantum emitters into photonic devices. A study conducted at the University of São Paulo’s São Carlos Institute of Physics (IFSC-USP) in Brazil has established a method for this, as described in an article published in the journal Nanomaterials.

“We demonstrated a method of embedding fluorescent nanodiamonds in designed for this purpose, using two-photon polymerization [2PP],” Cleber Mendonça, a professor at IFSC-USP and last author of the article, told Agência FAPESP. “We studied the ideal concentration of nanodiamond in the photoresist to achieve structures with at least one fluorescent NV center and good structural and optical quality.” The photoresist is a light-sensitive material used in the fabrication process to transfer nanoscale patterns to the substrate.

Researchers develop spintronic probabilistic computers compatible with current AI

Moore’s Law predicts that computers get faster every two years because of the evolution of semiconductor chips.

Researchers at Tohoku University and the University of California, Santa Barbara, have shown a proof-of-concept of energy-efficient computer compatible with current AI. It utilizes a stochastic behavior of nanoscale spintronics devices and is particularly suitable for probabilistic computation problems such as inference and sampling.

The team presented the results at the IEEE International Electron Devices Meeting (IEDM 2023) on December 12, 2023.

With the slowing down of Moore’s Law, there has been an increasing demand for domain-specific hardware. A probabilistic computer with naturally stochastic building blocks (probabilistic bits, or p-bits) is a representative example due to its potential capability to efficiently address various computationally hard tasks in machine learning (ML) and artificial intelligence (AI).

The Great Solar Wind Disappearance: Groundbreaking Discovery by NASA’s MAVEN Mission

In December 2022, NASA’s MAVEN mission observed a rare solar event causing the solar wind to “disappear.” This led to significant changes in Mars’ atmosphere and magnetosphere, including their expansion. Scientists, astounded by the data, formed a working group to study this phenomenon. Credit: SciTechDaily.com.

NASA ’s MAVEN detected a unique solar event that drastically affected Mars ’ atmosphere, offering vital insights into the planet’s interaction with solar phenomena.

In December 2022, NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) mission observed the dramatic and unexpected “disappearance” of a stream of charged particles constantly emanating off the Sun, known as the solar wind. This was caused by a special type of solar event that was so powerful, it created a void in its wake as it traveled through the solar system.

Physicists Hope to Finally Resolve Whether Gravity is Quantum by Levitating Micro Diamonds

If successful, the experiments would not only affirm some of the theories proposing the quantum nature of gravity but could also finally unify general relativity with theories of quantum mechanics.

Unifying General Relativity with Quantum Mechanics Has Proven Elusive

“General relativity and quantum mechanics are the two most fundamental descriptions of nature we have,” explains the press release announcing the new experiments. “General relativity explains gravity on large scales while quantum mechanics explains the behaviour of atoms and molecules.”

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