SLAC, Stanford researchers make a new type of quantum material with a dramatic distortion pattern

This illustration shows how an electronic tug-of-war between the layers of a new quantum material has warped its atomic lattice into a dramatic herringbone-like pattern. Scientists at SLAC and Stanford who created the material are just starting to explore how this 'huge' distortion affects the material's properties.   
Illustration Credit: Greg Stewart/SLAC National Accelerator Laboratory

Created by an electronic tug-of-war between the material's atomic layers, this ‘beautiful’ herringbone-like pattern could give rise to unique features that scientists are just starting to explore.

Researchers at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have created a new type of quantum material whose atomic scaffolding, or lattice, has been dramatically warped into a herringbone pattern.

The resulting distortions are “huge” compared to those achieved in other materials, said Woo Jin Kim, a postdoctoral researcher at the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC who led the study. 

“This is a very fundamental result, so it’s hard to make predictions about what may or may not come out of it, but the possibilities are exciting,” said SLAC/Stanford Professor and SIMES Director Harold Hwang. 

“Based on theoretical modeling from members of our team, it looks like the new material has intriguing magnetic, orbital and charge order properties that we plan to investigate further,” he said. Those are some of the very properties that scientists think give quantum materials their surprising characteristics. 

The research team described their work in a paper published in Nature today.

WVU physicists give the first law of thermodynamics a makeover

Research findings led by Paul Cassak, WVU professor and associate director of the WVU Center for KINETIC Plasma Physics, have broken new ground on how scientists can understand the first law of thermodynamics and how plasmas in space and laboratories get heated. In this photo, argon plasma glows a bluish color in a Center experiment.
Photo Credit: Brian Persinger / West Virginia University

West Virginia University physicists have made a breakthrough on an age-old limitation of the first law of thermodynamics.

Paul Cassak, professor and associate director of the Center for KINETIC Plasma Physics, and graduate research assistant Hasan Barbhuiya, both in the Department of Physics and Astronomy, are studying how energy gets converted in superheated plasmas in space. Their findings, funded by a grant from the National Science Foundation and published in the Physical Review Letters journal, will revamp scientists’ understanding of how plasmas in space and laboratories get heated up, and may have a wide variety of further applications across physics and other sciences.

The first law of thermodynamics states that energy can neither be created nor destroyed, but it can be converted into different forms.

“Suppose you heat up a balloon,” Cassak said. “The first law of thermodynamics tells you how much the balloon expands and how much hotter the gas inside the balloon gets. The key is that the total amount of energy causing the balloon to expand and the gas to get hotter is the same as the amount of heat you put into the balloon. The first law has been used to describe many things — including how refrigerators and car engines work. It’s one of the pillars of physics.”

Simulations show aftermath of black hole collision

New simulations of two black holes colliding near the speed of light reveal the mysterious physics of what one astrophysicist calls "one of the most violent events you can imagine in the universe."

"It's a bit of a crazy thing to blast two black holes head-on very close to the speed of light," said Thomas Helfer, a postdoctoral fellow at Johns Hopkins University who produced the simulations. "The gravitational waves associated with the collision might look anticlimactic, but this is one of the most violent events you can imagine in the universe."

The work, which appears today in Physical Review Letters, is the first detailed look at the aftermath of such a cataclysmic clash, and shows how a remnant black hole would form and send gravitational waves through the cosmos.

Black hole mergers are one of the few events in the universe energetic enough to produce detectable gravitational waves, which carry energy produced by massive cosmic collisions. Like ripples in a pond, these waves flow through the universe distorting space and time. But unlike waves traveling through water, they are extremely tiny, and propagate through "spacetime," the mind-bending concept that combines the three dimensions of space with the idea of time.

On the track of the big bang: The most sensitive detector for measuring radioactivity is now in dresden

Prof. Kai Zuber (right) and Steffen Turkat
Photo Credit: Courtesy of Technische Universität Dresden

The "Felsenkeller" underground laboratory in Dresden now hosts the most sensitive setup for measuring radioactivity in Germany and one of the most sensitive setups in the world. With the new detector, researchers at the Technische Universität Dresden and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) will in future be working at the highest international level on some of the most exciting questions in astrophysics, such as dark matter, stars or the Big Bang.

What is dark matter? What are neutrinos all about? How do stars work and what was actually going on in the universe in the first minutes after the Big Bang? To answer these questions, you need very sensitive detectors and a lot of skill. Only a few laboratories in the world have been able to perform such sensitive measurements so far. Recently, however, an ultra-sensitive detector has been set up in Germany, which will enable researchers to find answers to these questions in the future.

After long development work, researchers from the Institute for Nuclear and Particle Physics (Technische Universität Dresden) and the Institute for Radiation Physics (HZDR) have now put the setup into operation in the underground laboratory "Felsenkeller" Dresden. From now on, they will be able to analyze samples of substances and materials with radioactivity in the range of 100 microbequerels, in other words, samples with 100 million times less radioactivity than is present in the human body. This puts the measurement setup in the Felsenkeller laboratory among the world's most sensitive measuring instruments for radioactivity.

Discovering the magic in superconductivity’s ‘magic angle’

Left: Marc Bockrath, professor of physics. Center: Jeanie Lau, professor of physics. Right: Mohit Randeria, professor of physics.
Photo Credit: Photos courtesy of Ohio State University

Researchers have produced new evidence of how graphene, when twisted to a precise angle, can become a superconductor, moving electricity with no loss of energy.

In a study published today (Feb. 15, 2023) in the journal Nature, the team led by physicists at The Ohio State University reported on the key role that quantum geometry plays in allowing this twisted graphene to become a superconductor.

Graphene is a single layer of carbon atoms, the lead that is found in a pencil.

In 2018, scientists at the Massachusetts Institute of Technology discovered that, under the right conditions, graphene could become a superconductor if one piece of graphene were laid on top of another piece and the layers were twisted to a specific angle – 1.08 degrees – creating twisted bilayer graphene.

Ever since, scientists have been studying this twisted bilayer graphene and trying to figure out how this “magic angle” works, said Marc Bockrath, professor of physics at Ohio State and co-author of the Nature paper.

Scientists find first observational evidence linking black holes to dark energy

Artist’s impression of a supermassive black hole. Cosmological coupling allows black holes to grow in mass without consuming gas or stars.
Image Credit: UH Manoa

Searching through existing data spanning 9 billion years, a University of Michigan physicist and colleagues have uncovered the first evidence of “cosmological coupling”—a newly predicted phenomenon in Einstein’s theory of gravity, possible only when black holes are placed inside an evolving universe.

Gregory Tarlé, U-M professor of physics, and researchers from the University of Hawaii and other institutions across nine countries studied supermassive black holes at the heart of ancient and dormant galaxies to develop a description of them that agrees with observations from the past decade. Their findings are published in two journal articles, one in The Astrophysical Journal and the other in The Astrophysical Journal Letters.

The first study found that these black holes gain mass over billions of years in a way that can’t easily be explained by standard galaxy and black hole processes, such as mergers or accretion of gas. According to the second paper, the growth in mass of these black holes matches predictions for black holes that not only cosmologically couple, but also enclose vacuum energy—material that results from squeezing matter as much as possible without breaking Einstein’s equations, thus avoiding a singularity.

Engineers discover a new way to control atomic nuclei as “qubits”

Diagram illustrates the way two laser beams of slightly different wavelengths can affect the electric fields surrounding an atomic nucleus, pushing against this field in a way that nudges the spin of the nucleus in a particular direction, as indicated by the arrow.
Illustration Credit: Courtesy of the researchers | MIT
Creative Commons

In principle, quantum-based devices such as computers and sensors could vastly outperform conventional digital technologies for carrying out many complex tasks. But developing such devices in practice has been a challenging problem despite great investments by tech companies as well as academic and government labs.

Today’s biggest quantum computers still only have a few hundred “qubits,” the quantum equivalents of digital bits.

Now, researchers at MIT have proposed a new approach to making qubits and controlling them to read and write data. The method, which is theoretical at this stage, is based on measuring and controlling the spins of atomic nuclei, using beams of light from two lasers of slightly different colors. The findings are described in a paper published Tuesday in the journal Physical Review X, written by MIT doctoral student Haowei Xu, professors Ju Li and Paola Cappellaro, and four others.

Nuclear spins have long been recognized as potential building blocks for quantum-based information processing and communications systems, and so have photons, the elementary particles that are discreet packets, or “quanta,” of electromagnetic radiation. But coaxing these two quantum objects to work together was difficult because atomic nuclei and photons barely interact, and their natural frequencies differ by six to nine orders of magnitude.

When the light is neither "on" nor "off" in the nanoworld

Illustration of the slit-shaped nanostructure in gold with quantum state highlighted.
Illustration Credit: Daniel Fersch / Universität Würzburg

Scientists at the Universities of Würzburg and Bielefeld detect the quantum properties of collective optical-electronic oscillations on the nanoscale. The results could contribute to the development of novel computer chips.

Whether the light in our living spaces is on or off can be regulated in everyday life simply by reaching for the light switch. However, when the space for the light is shrunk to a few nanometers, quantum mechanical effects dominate, and it is unclear whether there is light in it or not. Both can even be the case at the same time, as scientists from the Julius-Maximilians-Universität Würzburg (JMU) and the University of Bielefeld show in the journal “Nature Physics.”

“Detecting these exotic states of quantum physics on the size scales of electrical transistors could help in the development of optical quantum technologies of future computer chips,” explains Würzburg professor Bert Hecht. The nanostructures studied were produced in his group.

The 'flip-flop' qubit: realization of a new quantum bit in silicon controlled by electric signals

Dr Tim Botzem, Professor Andrea Morello and Dr Rostyslav Savytskyy in the quantum computing lab at UNSW Sydney.
Photo Credit: Richard Freeman/UNSW

UNSW Sydney research demonstrates a new type of quantum bit in silicon, called ‘flip-flop’ qubit, which can facilitate the construction of a large-scale quantum computer.

A team led by Professor Andrea Morello has just demonstrated the operation of a new type of quantum bit, called ‘flip-flop’ qubit, which combines the exquisite quantum properties of single atoms, with easy controllability using electric signals, just as those used in ordinary computer chips.

A deliberate target: electrical control of a single-atom quantum bit

“Sometimes new qubits, or new modes of operations, are discovered by lucky accident. But this one was completely by design,” says Prof. Morello. “Our group has had excellent qubits for a decade, but we wanted something that could be controlled electrically, for maximum ease of operation. So, we had to invent something completely new.”

Mosquito’s DNA could provide clues on gene expression, regulation

Vinícius Contessoto (left) and José Onuchic are lead co-authors on the study published last month in Nature Communications.
Vinícius Contessoto
 is a researcher in the Center for Biological Theoretical Physics at Rice University.
José Onuchic
 is the Harry C. and Olga K. Wiess Chair of Physics and professor of chemistry and biosciences at Rice University.
Photo Credit: Gustavo Raskosky/Rice University

When it comes to DNA, one pesky mosquito turns out to be a rebel among species.

Researchers at Rice University’s Center for Theoretical Biological Physics (CTBP) are among the pioneers of a new approach to studying DNA. Instead of focusing on chromosomes as linear sequences of genetic code, they’re looking for clues on how their folded 3D shapes might determine gene expression and regulation.

For most living things, their threadlike chromosomes fold to fit inside the nuclei of cells in one of two ways. But the chromosomes of the Aedes aegypti mosquito — which is responsible for the transmission of tropical diseases such as dengue, chikungunya, zika, mayaro and yellow fever — defy this dichotomy, taking researchers at the CTBP by surprise.

The Aedes aegypti’s chromosomes organize as fluid-yet-oriented “liquid crystals,” different from all other species, according to their study published in Nature Communications.

Scientists boost quantum signals while reducing noise

This superconducting parametric amplifier can achieve quantum squeezing over much broader bandwidths than other designs, which could lead to faster and more accurate quantum measurements.
 Image Credit: Courtesy of the researchers

A certain amount of noise is inherent in any quantum system. For instance, when researchers want to read information from a quantum computer, which harnesses quantum mechanical phenomena to solve certain problems too complex for classical computers, the same quantum mechanics also imparts a minimum level of unavoidable error that limits the accuracy of the measurements.

Scientists can effectively get around this limitation by using “parametric” amplification to “squeeze” the noise –– a quantum phenomenon that decreases the noise affecting one variable while increasing the noise that affects its conjugate partner. While the total amount of noise remains the same, it is effectively redistributed. Researchers can then make more accurate measurements by looking only at the lower-noise variable.

A team of researchers from MIT and elsewhere has now developed a new superconducting parametric amplifier that operates with the gain of previous narrowband squeezers while achieving quantum squeezing over much larger bandwidths. Their work is the first to demonstrate squeezing over a broad frequency bandwidth of up to 1.75 gigahertz while maintaining a high degree of squeezing (selective noise reduction). In comparison, previous microwave parametric amplifiers generally achieved bandwidths of only 100 megahertz or less.

Scientists discover toughest known material at ultra-cold temperatures

Microstructure and fractography of the CrCoNi-based alloys
Image Credit: Dr Dong Liu

Researchers at the University of Bristol have discovered an alloy that shows increased strength at over -250°C, making it the toughest material on record.

The findings, published in Science, show that chromium-cobalt-nickel alloy displays a high fracture toughness in cryogenic temperatures paving the way for its use in extreme environments on Earth and in space.

The behavior of this particular combination of metals is caused by a phase transformation that, when combined with other nano-scale mechanisms, prevents crack formation and propagation.

Lead author Dr Dong Liu of Bristol’s School of Physics, explained: “This is very interesting because most alloys become more brittle with a decrease in temperature. I reference the sinking of liberty ships in WWII and Titanic which were due to the metals losing its ductility at low temperatures.”

“People often mix the concept of strength and toughness. If you Google, ‘what is the toughest materials on earth?’ ‘Diamond’ will jump out on the top line. Diamond is the hardest known material to date, but hardness is usually related to strength of a material - diamond is indeed very hard and strong but it is not tough.”

Breakthrough laboratory confirmation of key theory behind the formation of planets, stars and supermassive black holes

Pillars of Creation: By combining images of the iconic Pillars of Creation from two cameras aboard NASA’s James Webb Space Telescope, the universe has been framed in its glory. The pillars are the vast clouds of dust and gas in the foreground that swirl around and form celestial bodies. 
Hi-Res Zoomable Image
Photo Credit: JWST/NASA

The first laboratory realization of the longstanding but never-before confirmed theory of the puzzling formation of planets, stars and supermassive black holes by swirling surrounding matter has been produced at the Princeton Plasma Physics Laboratory (PPPL). This breakthrough confirmation caps more than 20 years of experiments at PPPL, which is based at Princeton University.

The puzzle arises because matter orbiting around a central object does not simply fall into it, due to what is called the conservation of angular momentum that keeps planets and the rings of Saturn from tumbling from their orbits. That’s because the outward centrifugal force balances out the inward pull of gravity on the orbiting matter. However, the clouds of dust and plasma called accretion disks that swirl around and collapse into celestial bodies do so in defiance of the conservation of angular momentum.    

The solution to this puzzle, a theory known as the Standard Magnetorotational Instability (SMRI), was first proposed in 1991 by University of Virginia theorists Steven Balbus and John Hawley. They built on the fact that in a fluid that conducts electricity, whether the fluid be plasma or liquid metal, magnetic fields behave like springs connecting different sections of the fluid. This allows ubiquitous Alfvén waves, named after Nobel Prize winner Hannes Alfvén, to create a turbulent back-and-forth force between the inertia of the swirling fluid and the springiness of the magnetic field, causing angular momentum to be transferred between different sections of the disk.

Researchers devise a new path toward ‘quantum light’

Photo Credit: Scientific Frontline stock image

The researchers, from the University of Cambridge, along with colleagues from the US, Israel and Austria, developed a theory describing a new state of light, which has controllable quantum properties over a broad range of frequencies, up as high as X-ray frequencies. Their results are reported in the journal Nature Physics.

The world we observe around us can be described according to the laws of classical physics, but once we observe things at an atomic scale, the strange world of quantum physics takes over. Imagine a basketball: observing it with the naked eye, the basketball behaves according to the laws of classical physics. But the atoms that make up the basketball behave according to quantum physics instead.

“Light is no exception: from sunlight to radio waves, it can mostly be described using classical physics,” said lead author Dr Andrea Pizzi, who carried out the research while based at Cambridge’s Cavendish Laboratory. “But at the micro and nanoscale so-called quantum fluctuations start playing a role and classical physics cannot account for them.”

Researchers take a step toward novel quantum simulators

A scanning electron microscope image of the "two-island" device, which researchers hope will pave the way toward a quantum simulator. 
Image Credit: Winston Pouse/Stanford University

Some of the most exciting topics in modern physics, such as high-temperature superconductors and some proposals for quantum computers, come down to the exotic things that happen when these systems hover between two quantum states.

Unfortunately, understanding what's happening at those points, known as quantum critical points, has proved challenging. The math is frequently too hard to solve, and today's computers are not always up to the task of simulating what happens, especially in systems with any appreciable number of atoms involved.

Now, researchers at Stanford University and the Department of Energy's SLAC National Accelerator Laboratory and their colleagues have taken a step toward building an alternative approach, known as a quantum simulator. Although the new device, for now, only simulates the interactions between two quantum objects, the researchers argue in a paper published in Nature Physics that it could be scaled up relatively easily. If so, researchers could use it to simulate more complicated systems and begin answering some of the most tantalizing questions in physics. 

A quasiparticle that can transfer heat under electrical control

Because thermal conductivity in this class of materials can be changed with application of an external electric field at room temperature, they hold promise for use in heat switches for everyday applications, like collection of solar power.
Photo Credit: American Public Power Association

Scientists have found the secret behind a property of solid materials known as ferroelectrics, showing that quasiparticles moving in wave-like patterns among vibrating atoms carry enough heat to turn the material into a thermal switch when an electrical field is applied externally.

A key finding of the study is that this control of thermal conductivity is attributable to the structure of the material rather than any random collisions among atoms. Specifically, the researchers describe quasiparticles called ferrons whose polarization changes as they “wiggle” in between vibrating atoms – and it’s that ordered wiggling and polarization, receptive to the externally applied electrical field, that dictates the material’s ability to transfer the heat at a different rate.

“We figured out that this change in position of these atoms, and the change of the nature of the vibrations, must carry heat, and therefore the external field which changes this vibration must affect the thermal conductivity,” said senior author Joseph Heremans, professor of mechanical and aerospace engineering, materials science and engineering, and physics at The Ohio State University. 

A new way to explore proton’s structure with neutrinos yields first results

One of two magnetic focusing horns used in the beamline at Fermilab that produces intense neutrino beams for MINERvA and other neutrino experiments.
Photo Credit: Reidar Hahn, Fermilab

Physicists used MINERvA, a Fermilab neutrino experiment, to measure the proton’s size and structure using a neutrino-scattering technique.

For the first time, particle physicists have been able to precisely measure the proton’s size and structure using neutrinos. With data gathered from thousands of neutrino-hydrogen scattering events collected by MINERvA, a particle physics experiment at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, physicists have found a new lens for exploring protons. The results were published today in the scientific journal Nature.

This measurement is also important for analyzing data from experiments that aim to measure the properties of neutrinos with great precision, including the future Deep Underground Neutrino Experiment, hosted by Fermilab.

“The MINERvA experiment has found a novel way for us to see and understand proton structure, critical both for our understanding of the building blocks of matter and for our ability to interpret results from the flagship DUNE experiment on the horizon,” said Bonnie Fleming, Fermilab deputy director for science and technology.

Solid material that 'upconverts' visible light photons to UV light photons could change how we utilize sunlight

Low-intensity visible blue light or lower energy photons being converted into higher energy UV photons using a solid film formed on a round glass substrate, developed by researchers at Tokyo Tech
 Image Credit: Prof. Yoichi Murakami

Ultraviolet (UV) light has higher energy photons than visible light and, thus, has more applications. Tokyo Tech researchers have now developed a brilliant innovation—a solid-state material that can stably and efficiently upconvert sunlight- intensity visible light photons to UV light photons. This photon upconversion (UC) material can utilize visible light to successfully drive reactions that would conventionally need UV light, broadening the spectrum of utility for the former.

The importance of solar power as a renewable energy resource is increasing. Sunlight contains high-energy UV light with a wavelength shorter than 400 nm, which can be broadly used, for example, for photopolymerization to form a resin and activation of photocatalysts to drive reactions that generate green hydrogen or useful hydrocarbons (fuels, sugars, olefins, etc.). The latter of these is often called "artificial photosynthesis." Photocatalytic reaction by UV light to efficiently kill viruses and bacteria is another important application. Unfortunately, only about 4% of terrestrial sunlight falls within the UV range in the electromagnetic spectrum. This leaves a large portion of sunlight spectrum unexploited for these purposes.

Astronomers reveal new map of dark matter, mass in universe

Victor M. Blanco 4-meter Telescope, left, at the Cerro Tololo Inter-American Observatory in Chile houses the camera used by the Dark Energy Survey.
Image Credit: Dark Energy Survey

For decades, cosmologists have mapped the distribution of mass in the universe, both visible material and the mysterious dark matter, in an effort to improve our understanding of these fundamental building blocks. Astronomer Eric Baxter from the University of Hawaiʻi Institute for Astronomy co-authored new research that traces the mass distribution in the universe in three dimensions. The updated analysis was published in Physical Review D.

Baxter and his University of Chicago collaborators, Chihway Chang and Yuuki Omori, compiled data using two different sky surveying methods. This new analysis shows that there is six times as much dark matter in the universe compared to matter that is visible—a finding that was already well-known. However, the team also found that the matter is not as clumpy as previously expected when compared to the current best model of the universe.

The researchers claim the findings could add to a growing body of evidence that there may be something missing from the existing standard model of the universe.

New type of solar cell is being tested in space

Magnus Borgström Professor, Solid State Physics Lund University
Photo Credit: Lund University

Physics researchers at Lund University in Sweden recently succeeded in constructing small solar radiation-collecting antennas – nanowires – using three different materials that are a better match for the solar spectrum compared with today’s silicon solar cells. As the nanowires are light and require little material per unit of area, they are now to be installed for tests on satellites, which are powered by solar cells and where efficiency, in combination with low weight, is the most important factor. The new solar cells were sent into space a few days ago.

A group of nanoengineering researchers at Lund University working on solar cells made a breakthrough last year when they succeeded in building photovoltaic nanowires with three different band gaps. This, in other words, means that one and the same nanowire consists of three different materials that react to different parts of solar light. The results have been published in Materials Today Energy and subsequently in more detail in Nano Research.

“The big challenge was to get the current to transfer between the materials. It took more than ten years, but it worked in the end,” says Magnus Borgström, professor of solid-state physics, who wrote the articles with the then doctoral student Lukas Hrachowina.