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Perturbing electron spins in a magnet usually results in excitations called “spin waves” that ripple through the magnet like waves on a pond that’s been struck by a pebble. In a new study, Rice University physicists and their collaborators have discovered dramatically different excitations called “spin excitons” that can also “ripple” through a nickel-based magnet as a coherent wave.

In a study published in Nature Communications, the researchers reported finding unusual properties in nickel molybdate, a layered magnetic crystal. Subatomic particles called electrons resemble miniscule magnets, and they typically orient themselves like compass needles in relation to magnetic fields. In experiments where neutrons were scattered from magnetic nickel ions inside the crystals, the researchers found that two outermost electrons from each nickel ion behaved differently. Rather than aligning their spins like compass needles, the two canceled one another in a phenomenon physicists call a spin singlet.

“Such a substance should not be a magnet at all,” said Rice’s Pengcheng Dai, corresponding author of the study. “And if a neutron scatters off a given nickel ion, the excitations should remain local and not propagate through the sample.”

The universe began about 14 billion years ago with a single point that contained a vast array of fundamental particles, according to the prevailing theory known as the Big Bang. Under the pressure of extreme heat and energy, the point inflated and then expanded to become the universe as we know it. That expansion continues to this day.

Unlocking the mysteries of what happened in that first instant is a key subject of nuclear physics research. Rosi Reed, associate professor, and Anders Knospe, assistant professor―both in the Department of Physics―are on the leading edge of that research, probing the nature of that initial matter created, quark-gluon plasma, a fluid made up of subatomic particles. With support from the National Science Foundation, they have built a highly-specialized detector to measure aspects of the universe that have never before been measured.

Reed and Knospe are installing their event plane detector at Brookhaven National Laboratory’s Relativistic Ion Collider (RHIC) in Long Island, New York, one of only two operating particle collider facilities in existence. They are running experiments to forward their collaborative and individual research on the strong nuclear force, one of the four fundamental forces of nature, along with gravity, electromagnetism and the weak nuclear force. The strong force holds atomic nuclei together.

😗 year 2010 :3.

(PhysOrg.com) — Scientists have literally taken a leap into a new era of computing power by making the world’s smallest precision-built transistor — a “quantum dot” of just seven atoms in a single silicon crystal. Despite its incredibly tiny size — a mere four billionths of a metre long — the quantum dot is a functioning electronic device, the world’s first created deliberately by placing individual atoms.

It can be used to regulate and control electrical current flow like a commercial transistor but it represents a key step into a new age of atomic-scale miniaturisation and super-fast, super-powerful computers.

Continue reading “Quantum leap: World’s smallest transistor built with just 7 atoms” »

Year 2022 😗

Argonne National Laboratory, Lemont, IL

A team of scientists at the U.S. Department of Energy’s Argonne National Laboratory, have achieved efficient quantum coupling between two distant magnetic devices, which can host a certain type of magnetic excitations called magnons. These excitations happen when an electric current generates a magnetic field. Coupling allows magnons to exchange energy and information. This kind of coupling may be useful for creating new quantum information technology devices.

Continue reading “Tiny Magnets to Create Miniaturizable Quantum Devices” »

The QCD vacuum (i.e., the ground state of vacuum in the quantum chromodynamics regime) is theoretically characterized by the presence of non-zero expectation values of condensates, such as gluons and quark–antiquark pairs. Instead of being associated with a lack of particles and interactions in an empty space, physics theory regards this state as filled with the so-called condensates, which have the same quantum numbers as the vacuum and cannot be directly observed.

While many theoretical physicists have discussed the properties of the QCD vacuum, experimentally validating these theoretical predictions has so far proved challenging, simply because the condensates in this state are elusive and cannot be directly detected. A hint of experimental “observation” can be found in the theoretical predictions of the properties of the QCD vacuum.

Theories predict that the condensate may decrease in the high temperature and/or at a high matter density due to the partial restoration of the so-called chiral symmetry. To prove these theories, some researchers collected measurements during ultra-relativistic, head-on collisions of heavy ions at particularly high temperatures. Other efforts in this area tried to probe properties of the QCD vacuum by measuring so-called “medium effects.” These are essentially effects that alter the QCD vacuum and its structure, prompted by the presence of high matter density such as nuclear matter.

The ATLAS collaboration, the large research consortium involved in analyzing data collected by the ATLAS particle collider at CERN, recently observed the electroweak production of two Z bosons and two jets. This crucial observation, presented in Nature Physics, could greatly contribute to the understanding of standard model ℠ particle physics.

The SM of particle physics is a well-established theory describing the building blocks and fundamental forces in the universe. This model describes weak bosons (i.e., bosons responsible for the so-called ‘weak force’) as mediators of the electroweak interaction.

The scattering of massive weak bosons, such as W and Z bosons, is constrained specifically to interactions, where the mediators directly interact and scatter off each other. This scattering, also known as vector-boson scattering (VBS), also involves a type of Feynman diagrams or vertices known (i.e., quartic gauge vertices) that physicists have so far been unable to experimentally probe through other physical processes.

Developing new quantum devices relies on controlling how electrons behave. A material called graphene, a single layer of carbon atoms, has fascinated researchers in recent years because its electrons behave as if they have no mass. For decades, scientists have also been interested in high-temperature superconductors: ceramic materials where electron interactions yield a macroscopic quantum state where electrons pair with each other. They do so at a temperature above the usual superconducting temperature of metals, which approaches absolute zero.

In a recent study published in Physical Review Letters, researchers from the SUNY Polytechnic Institute, Stony Brook University and the Brookhaven National Laboratory in the US, along with Aalto University in Finland, demonstrated a new electronic device that employs the unique ways in which electrons behave in these two materials— graphene and high-temperature superconductors.

The experiment, led by Sharadh Jois and Ji Ung Lee from SUNY with the support of theoretical work done by Jose Lado, assistant professor at Aalto, demonstrated a new quantum device that combines both graphene and an unconventional high-temperature superconductor.

Primordial holes formed in the exotic conditions of the big bang may have become their own source of matter and radiation.

The standard story of the early universe goes like this. When our cosmos was incredibly young, it underwent a period of incredibly rapid expansion known as inflation. Then inflation went away and flooded the universe with particles and radiation in the hot big bang. Then the universe expanded and cooled, and as it did so the density of that matter and radiation dropped. Eventually the matter got itself together informed stars, galaxies and clusters.

Continue reading “Primordial Black Holes May Have ‘Frozen’ the Early Universe” »

The discovery of new quantum materials with magnetic properties could pave the way for ultra-fast and considerably more energy-efficient computers and mobile devices. So far, these types of materials have been shown to work only in extremely cold temperatures. Now, a research team at Chalmers University of Technology in Sweden are the first to make a device made of a two-dimensional magnetic quantum material work in room temperature.

Today’s rapid IT expansion generates enormous amounts of digital data that needs to be stored, processed, and communicated. This comes with an ever-increasing need for energy—projected to consume more than 30% of the world’s total energy consumption by 2050. To combat the problem, the research community has entered a new paradigm in materials science. The research and development of two-dimensional quantum materials, that form in sheets and are only a few atoms thick, have opened new doors for sustainable, faster and more energy-efficient data storage and processing in computers and mobiles.

The first atomically thin material to be isolated in a laboratory was graphene, a single atom-thick plane of graphite, that resulted in the 2010 Nobel Prize in Physics. And in 2017, two-dimensional materials with magnetic properties were discovered for the first time. Magnets play a fundamental role in our everyday lives, from sensors in our cars and home appliances to computer data storage and memory technologies, and the discovery opened for new and more sustainable solutions for a wide range of technology devices.