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Category: particle physics

How Neutrino Oscillations Affect Supernovae

Numerical models of core-collapse supernovae have matured greatly over the past few decades. With impressive accuracy, they now couple relativistic gravity, magnetohydrodynamics, nuclear physics, and neutrino transport. Neutrinos, copiously produced in the collapsed core, are the main driver of most of these supernovae. Neutrino oscillations are probably the most crucial ingredient that is still missing from the majority of models, even though their presence and possible importance have long been suggested. The reason for this gap in modeling is twofold: Many relevant physical parameters are poorly known, and the most important oscillation processes are very difficult to simulate. Now Ryuichiro Akaho at Waseda University in Japan and colleagues have made a key step toward a self-consistent model and revealed some complexities that arise when incorporating neutrino oscillations [1].

Stars are supported against their own gravity primarily by gas pressure, which is maintained by exothermic nuclear reactions. In high-mass stars, nuclear burning starts with the fusion of hydrogen into helium and continues through progressively heavier elements until the core is dominated by iron-group nuclei, at which point fusion no longer releases energy. Pressure support then no longer suffices to stabilize the core, and it collapses to a protoneutron star, a hot compact object with about 1.5 solar masses concentrated in a radius of a few tens of kilometers. During the collapse, a shock wave forms at this object’s surface and stalls after propagating outward for only about 100 km (Fig. 1). Neutrinos generated in and around the protoneutron star can heat the surrounding gas, increasing its energy.

Quantum dot emitter delivers near-identical telecom photons at 40 million per second

Quantum technologies, devices that perform specific functions leveraging quantum mechanical effects, could soon outperform their classical counterparts on some tasks. Quantum emitters, devices that release individual particles of light (i.e., photons), are central components of many of these technologies, including quantum communication systems and quantum computers.

To enable the reliable operation of quantum technologies, emitters should emit photons with high consistency and coherence. In other words, they should ensure that the quantum properties of emitted photons remain stable and predictable.

Researchers at University of Copenhagen’s Niels Bohr Institute, Ruhr-University Bochum, University of Basel and Sparrow Quantum ApS recently developed a new photon emitter based on quantum dots, tiny structures that can trap electrons in confined regions and enable the controlled emission of individual photons.

Light reshapes metal-organic framework to harvest airborne water

Chemists at the University of Iowa have created a three-dimensional lattice that captures water from the air and stores it. In a new study appearing in the Journal of the American Chemical Society, researchers describe a millimeter-scale structure made of metal atoms connected by two types of organic molecules. When exposed to ultraviolet light, the material undergoes a chemical reaction that changes its shape, creating cavities throughout the lattice. Those cavities attract water molecules from the air and store them—like a multitude of tiny canteens.

The results, which would need to be tested at larger scales, show promise as a method to help provide drinking water to people and areas with limited access. Water stress or scarcity will affect nearly five billion people—half the world’s projected population—by 2050, according to the United Nations.

“We have found and validated a way to capture and to store water that would require only sunlight,” says Leonard MacGillivray, adjunct professor in the Department of Chemistry and former professor and department chair. “You can transport the crystal lattice and eventually release the water on demand. That’s why it’s such an advance.”

Unexplored interactions between electrons and atomic nuclei shed light on dark matter

Dark matter particles could be mediators of the interaction between electrons and atomic nuclei, as shown by a study conducted by junior group leader, Dr. Konstantin Gaul, Dr. Lei Cong, and Professor Dr. Dmitry Budker, of Johannes Gutenberg University Mainz (JGU), Helmholtz Institute Mainz (HIM) and the PRISMA++ Cluster of Excellence. Their work, published last week in Physical Review Letters, presents new constraints on previously unexplored candidates for dark matter and, more generally, some hypothetical particles that are not included in the Standard Model of particle physics ℠.

Using results from precision measurements on barium monofluoride (BaF) molecules, the team constrained these interactions mediated by Z’ bosons for the first time. Z’ bosons are hypothetical mediators of the weak interaction and possible dark matter particles in several SM extensions. “These results address a significant blind spot in physics: a regime of forces between electrons and nuclei that had remained unexplored by both laboratory experiments and cosmological data,” explained Gaul.

Our universe is made up of about 4% of visible, or ordinary, matter. This includes planets, stars, and life on Earth. The remaining 96% of the universe is invisible and consists of dark matter and dark energy, with dark matter making up about 23%. Astrophysical observations confirm its presence throughout the cosmos, where it, for example, plays an important part in the structure of galaxies. However, we don’t know what particles make up dark matter. Many theories and ongoing experiments are looking for an answer to this open question.

Researchers find coherent ferrons—polarization waves with potential across quantum and telecom applications

In new research published in Nature Materials, a team of researchers led by Columbia University chemist Xiaoyang Zhu, in collaboration with fellow Columbians Xavier Roy, Milan Delor, Dmitri Basov, and James McIver, has observed coherent ferrons for the first time.

Ferrons are electronic quasiparticles, predicted since the 1960s, that carry polarization. The oscillating polarization wave that the team, led by Columbia postdocs Jeongheon Choe and Taketo Handa, observed represents a new type of information carrier that could prove much faster than conventional electronics.

In ferroelectric materials, the dipole moments of unit cells line up, becoming polarized. Collective excitation of these dipoles creates the ferron quasiparticle, which has an inherent dipole moment. This means one side of each tiny particle is slightly more negatively charged than the other. Ferrons are similar to another quasiparticle that’s been of interest to Zhu and colleagues in recent years: magnons.

New ‘trick’ fixes major flaw in neutral-atom quantum computers — inching us closer to a superpowerful system

A new “geometry‑based” quantum swap gate makes neutral‑atom computers far less sensitive to laser noise — bringing large‑scale, stable quantum processors a step closer to reality.

A bizarre new state of matter may be hiding inside Uranus and Neptune

Deep inside planets like Uranus and Neptune, scientists may have uncovered a bizarre new state of matter where atoms behave in unexpected ways. Advanced simulations suggest that carbon and hydrogen, under crushing pressures and scorching temperatures, can form a strange hybrid phase—part solid, part fluid—where hydrogen atoms spiral through a rigid carbon framework. This unusual “superionic” structure could reshape how heat and electricity flow inside these distant worlds, potentially helping explain their mysterious magnetic fields.

The deep interiors of ice giant planets such as Uranus and Neptune may contain a previously unknown form of matter. This possibility comes from new computer simulations conducted by Carnegie scientists Cong Liu and Ronald Cohen.

Their study, published in Nature Communications, suggests that carbon hydride could take on an unusual quasi-one-dimensional superionic state under the intense pressures and temperatures found far beneath the surfaces of these distant planets.

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