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Category: particle physics – Page 4

Dark matter search narrows as detector sets new limits and spots solar neutrinos

Australian researchers have played a central role in a landmark result from the LUX-ZEPLIN (LZ) experiment in South Dakota—the world’s most sensitive dark matter detector. Today, scientists working on the experiment report they have further narrowed constraints on proposed dark matter particles. And, for the first time, the experiment has detected elusive neutrinos produced deep inside the sun.

Scientists hypothesize that dark matter makes up about a quarter of the universe’s mass (or 85% of its matter) but have yet to detect exactly what makes up this strange phenomenon. The result announced today by the LZ experiment is one of the world’s most sensitive measurements in the hunt for dark matter. It has expanded its search for WIMPs (weakly interacting massive particles) down to masses approximately between that of three and nine times that of a proton, the positively charged particle in the nucleus of an atom.

Dr. Theresa Fruth, from the University of Sydney’s School of Physics, is one of only two Australian-based researchers in the 250-member international collaboration.

Tiny particles ‘surf’ microcosmic waves to save energy in chaotic environments

Conditions can get rough in the micro- and nanoworld. For example, to ensure that nutrients can still be optimally transported within cells, the minuscule transporters involved need to respond to the fluctuating environment. Physicists at Heinrich Heine University Düsseldorf (HHU) and Tel Aviv University in Israel have used model calculations to examine how this can succeed. They have now published their results—which could also be relevant for future microscopic machines—in the journal Nature Communications.

Scientists Discover How To “Purify” Light, Paving the Way for Faster, More Secure Quantum Technology

University of Iowa scientists have identified a new way to “purify” photons, a development that could improve both the efficiency and security of optical quantum technologies.

The team focused on two persistent problems that stand in the way of producing a reliable stream of single photons, which are essential for photonic quantum computers and secure communication systems. The first issue, known as laser scatter, arises when a laser is aimed at an atom to trigger the release of a photon, the basic unit of light. Although this method successfully generates photons, it can also produce extra, unwanted ones. These additional photons reduce the efficiency of the optical system, similar to how stray electrical currents interfere with electronic circuits.

A second complication comes from the way atoms occasionally respond to laser light. In uncommon cases, an atom releases more than one photon at the same time. When this happens, the precision of the optical circuit suffers because the extra photons disrupt the intended orderly flow of single photons.

Neurons use physical signals, not electricity, to stabilize communication

Every movement you make and every memory you form depends on precise communication between neurons. When that communication is disrupted, the brain must rapidly rebalance its internal signaling to keep circuits functioning properly. New research from the USC Dornsife College of Letters, Arts and Sciences shows that neurons can stabilize their signaling using a fast, physical mechanism—not the electrical activity scientists long assumed was required.

The discovery, published recently in Proceedings of the National Academy of Sciences, reveals a system that doesn’t depend on the flow of charged particles to maintain signaling when part of a synapse—the junction between neurons—suddenly stops working.

Maintaining this balance between neurons is essential for muscle control, learning and overall brain health. Failure to maintain this “homeostasis” has been linked to neurological conditions such as epilepsy and autism.

CERN Scientists Solve Decades-Old Particle Physics Mystery

Researchers from TUM, working at CERN, have made a groundbreaking discovery that reveals how deuterons are formed. Another long-standing question in particle physics has been answered. Scientists working with the ALICE experiment at CERN’s Large Hadron Collider (LHC), led by researchers from the

Cracking the mystery of heat flow in few-atoms thin materials

For much of my career, I have been fascinated by the ways in which materials behave when we reduce their dimensions to the nanoscale. Over and over, I’ve learned that when we shrink a material down to just a few nanometers in thickness, the familiar textbook rules of physics begin to bend, stretch, or sometimes break entirely. Heat transport is one of the areas where this becomes especially intriguing, because heat is carried by phonons—quantized vibrations of the atomic lattice—and phonons are exquisitely sensitive to spatial confinement.

A few years ago, something puzzling emerged in the literature. Molecular dynamics simulations showed that ultrathin silicon films exhibit a distinct minimum in their thermal conductivity at around one to two nanometers thickness, which corresponds to just a few atomic layers. Even more surprisingly, the thermal conductivity starts to increase again if the material is made even thinner, approaching extreme confinement and the 2D limit.

This runs counter to what every traditional model would predict. According to classical theories such as the Boltzmann transport equation or the Fuchs–Sondheimer boundary-scattering framework, reducing thickness should monotonically suppress thermal conductivity because there is simply less room for phonons to travel freely and carry heat around. Yet the simulations done by the team of Alan McGaughey at Carnegie Mellon University in Pittsburgh insisted otherwise, and no established theory could explain why.

An Old Jeweler’s Trick Could Unlock the Next Generation of Nuclear Clocks

Last year, a research team led by UCLA achieved a milestone scientists had pursued for half a century. They succeeded in making radioactive thorium nuclei interact with light by absorbing and emitting photons, similar to how electrons behave inside atoms. First envisioned by the group in 2008, the breakthrough is expected to transform precision timekeeping and could significantly improve navigation systems, while also opening the door to discoveries that challenge some of the most basic constants in physics.

The advance comes with a major limitation. The required isotope, thorium-229, exists only as a byproduct of weapons-grade uranium, making it extremely rare. Researchers estimate that just 40 grams of this material are currently available worldwide for use in nuclear clock research.

A new study now shows a way around this obstacle. An international collaboration led by UCLA physicist Eric Hudson has developed an approach that uses only a small fraction of the thorium needed in earlier experiments, while delivering the same results previously achieved with specialized crystals. Described in Nature, the technique is both straightforward and low cost, raising the possibility that nuclear clocks could one day be small and affordable enough to fit into everyday devices like phones or wristwatches. Beyond consumer electronics, the clocks could replace existing systems used in power grids, cell phone towers, and GPS satellites, and may even support navigation where GPS is unavailable, such as in deep space or underwater.

Caltech Team Sets Record with 6,100-Qubit Array

Quantum computers will need large numbers of qubits to tackle challenging problems in physics, chemistry, and beyond. Unlike classical bits, qubits can exist in two states at once—a phenomenon called superposition. This quirk of quantum physics gives quantum computers the potential to perform certain complex calculations better than their classical counterparts, but it also means the qubits are fragile. To compensate, researchers are building quantum computers with extra, redundant qubits to correct any errors. That is why robust quantum computers will require hundreds of thousands of qubits.

Now, in a step toward this vision, Caltech physicists have created the largest qubit array ever assembled: 6,100 neutral-atom qubits trapped in a grid by lasers. Previous arrays of this kind contained only hundreds of qubits.

This milestone comes amid a rapidly growing race to scale up quantum computers. There are several approaches in development, including those based on superconducting circuits, trapped ions, and neutral atoms, as used in the new study.

The neutral-atom platform shows promise for scaling up quantum computers.

Pinpointing the glow of a single atom to advance quantum emitter engineering

Researchers have discovered how to design and place single-photon sources at the atomic scale inside ultrathin 2D materials, lighting the path for future quantum innovations.

Like perfectly controlled light switches, quantum emitters can turn on the flow of single particles of light, called photons, one at a time. These tiny switches—the “bits” of many quantum technologies—are created by atomic-scale defects in materials.

Their ability to produce light with such precision makes them essential for the future of quantum technologies, including quantum computing, secure communication and ultraprecise sensing. But finding and controlling these atomic light switches has been a major scientific challenge—until now.

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