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Category: particle physics – Page 11

Ultrafast spin-exchange in quantum dots enhances solar energy and photochemical efficiency

Quantum dots are microscopic semiconductor crystals developed in the lab that share many properties with atoms, including the ability to absorb or emit light, a technology that Los Alamos researchers have spent nearly three decades evolving. Through carrier multiplication, in which a single absorbed photon generates two electron-hole pairs, called excitons, quantum dots have the unique ability to convert photons more efficiently to energy.

“Our work demonstrates how purely quantum mechanical spin-exchange interactions can be harnessed to enhance the efficiency of photoconversion devices or ,” says Victor Klimov, the team’s principal investigator at the Lab. “This not only deepens our fundamental understanding of quantum mechanical phenomena but also introduces a new paradigm for designing advanced materials for energy applications.”

In this latest research, published in the journal Nature Communications, Los Alamos researchers improved this ability by introducing magnetic manganese impurities into quantum dots. This novel approach to highly efficient carrier multiplication leverages ultrafast spin-exchange interactions mediated by manganese ions to capture the energy of energetic (hot) carriers generated by incident photons and convert it into additional excitons.

World’s first non-silicon 2D computer developed

Silicon is king in the semiconductor technology that underpins smartphones, computers, electric vehicles and more, but its crown may be slipping, according to a team led by researchers at Penn State.

In a world first, they used two-dimensional (2D) materials, which are only an atom thick and retain their properties at that scale, unlike , to develop a computer capable of simple operations.

The development, published in Nature, represents a major leap toward the realization of thinner, faster and more energy-efficient electronics, the researchers said.

First quantum-mechanical model of quasicrystals reveals why they exist

A rare and bewildering intermediate between crystal and glass can be the most stable arrangement for some combinations of atoms, according to a study from the University of Michigan.

The findings come from the first quantum-mechanical simulations of quasicrystals—a type of solid that scientists once thought couldn’t exist. While the atoms in quasicrystals are arranged in a lattice, as in a crystal, the pattern of atoms doesn’t repeat like it does in conventional crystals. The new simulation method suggests quasicrystals—like crystals—are fundamentally , despite their similarity to disordered solids like glass that form as a consequence of rapid heating and cooling.

“We need to know how to arrange atoms into specific structures if we want to design materials with desired properties,” said Wenhao Sun, the Dow Early Career Assistant Professor of Materials Science and Engineering, and the corresponding author of the paper published today in Nature Physics. “Quasicrystals have forced us to rethink how and why certain materials can form. Until our study, it was unclear to scientists why they existed.”

New approach reversibly configures single and heteronuclear dual-atom catalysts on MoS₂ substrate

Single-atom catalysts (SACs) are materials consisting of individual metal atoms dispersed on a substrate (i.e., supporting surface). Recent studies have highlighted the promise of these catalysts for the efficient conversion and storage of energy, particularly when deployed in fuel cells and water electrolyzers.

Decoding high energy physics with AI and machine learning

In the world of particle physics, where scientists unravel the mysteries of the universe, artificial intelligence (AI) and machine learning (ML) are making waves with how they’re increasing understanding of the most fundamental particles. Central to this exploration are parton distribution functions (PDFs). These complex mathematical models are crucial for predicting outcomes of high energy physics experiments that test the Standard Model of particle physics.

Recent developments in klystron technology for future energy-efficient colliders

The Higgs boson is the most intriguing and unusual object yet discovered by fundamental science. There is no higher experimental priority for particle physics than building an electron–positron collider to produce it copiously and study it precisely.

Given the importance of energy efficiency and cost effectiveness in the current geopolitical context, this gives unique strategic importance to developing a humble technology called the klystron—a technology that will consume the majority of site power at every major electron–positron collider under consideration, but which has historically only achieved 60% energy efficiency.

The klystron was invented in 1937 by two American brothers, Russell and Sigurd Varian. The Varians wanted to improve aircraft radar systems. At the time, there was a growing need for better high-frequency amplification to detect objects at a distance using radar, a critical technology in the lead-up to World War II.

Scientists achieve precision activation of quantum defects in diamond

A new study led by researchers at the Universities of Oxford, Cambridge and Manchester has achieved a major advance in quantum materials, developing a method to precisely engineer single quantum defects in diamond—an essential step toward scalable quantum technologies. The results have been published in the journal Nature Communications.

Using a new two-step fabrication method, the researchers demonstrated for the first time that it is possible to create and monitor, “as they switch on,” individual Group-IV quantum defects in diamond—tiny imperfections in the diamond that can store and transmit information using the exotic rules of quantum physics.

By carefully placing single tin atoms into synthetic diamond crystals and then using an ultrafast laser to activate them, the team achieved pinpoint control over where and how these quantum features appear. This level of precision is vital for making practical, large-scale quantum networks capable of ultra-secure communication and distributed quantum computing to tackle currently unsolvable problems.

Harnessing magnons for quantum information processing

Researchers have determined how to use magnons—collective vibrations of the magnetic spins of atoms—for next-generation information technologies, including quantum technologies with magnetic systems.

From the computer hard drives that store our data to the motors and engines that drive power plants, magnetism is central to many transformative technologies. Magnetic materials are expected to play an even larger role in new technologies on the horizon: the transmission and processing of quantum information and the development of quantum computers.

New research led by scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory developed an approach to control the collective magnetic properties of atoms in real time and potentially deploy them for next-generation information technologies. This discovery could aid in developing future quantum computers, which can perform tasks that would be impossible using today’s computers, as well as “on chip” technologies—with magnetic systems embedded on semiconductor chips, or “on chip.”

New class of ‘X-type’ antiferromagnets enables sublattice-selective spin transport

A research team led by Prof. Shao Dingfu from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has predicted a new class of antiferromagnetic materials with unique cross-chain structures, termed “X-type antiferromagnets.” These materials exhibit sublattice-selective spin transport and unconventional magnetic dynamics, offering new possibilities for next-generation spintronic devices.

Published in Newton, this work challenges conventional views of collective atomic behavior in solids and promises transformative applications in next-generation electronics.

Antiferromagnets (AFMs) are valued for their zero net magnetization and ultrafast dynamics, making them attractive for spintronics. However, their practical application has been hindered by mutual spin cancellation between magnetic sublattices, which limits spin current control. The newly proposed X-type AFMs, with their distinctive “X”-shaped intersecting chain geometry, overcome this limitation.