In a quantum engine, a single atom can emit radiation that bounces around a reflective cavity and creates enough pressure to push down a piston.
Cosmologists are wrestling with an interesting question: how much clumpiness does the Universe have? There are competing but not compatible measurements of cosmic clumpiness and that introduces a “tension” between the differing measurements. It involves the amount and distribution of matter in the Universe. However, dark energy and neutrinos are also in the mix. Now, results from a recent large X-ray survey of galaxy clusters may help “ease the tension”
The eROSITA X-ray instrument orbiting beyond Earth performed an extensive sky survey of galaxy clusters to measure matter distribution (clumpiness) in the Universe. Scientists at the Max Planck Institute for Extraterrestrial Physics recently shared their analysis of its cosmologically important data.
“eROSITA has now brought cluster evolution measurement as a tool for precision cosmology to the next level,” said Dr. Esra Bulbul (MPE), the lead scientist for eROSITA’s clusters and cosmology team. “The cosmological parameters that we measure from galaxy clusters are consistent with state-of-the-art cosmic microwave background, showing that the same cosmological model holds from soon after the Big Bang to today.”
Neutron stars in the universe, ultracold atomic gases in the laboratory, and the quark–gluon plasma created in collisions of atomic nuclei at the Large Hadron Collider (LHC): they may seem totally unrelated but, surprisingly enough, they have something in common.
They are all a fluid-like state of matter made up of strongly interacting particles. Insights into the properties and behavior of any of these almost-perfect liquids may be key to understanding nature across scales that are orders of magnitude apart.
In a new paper, the CMS collaboration reports the most precise measurement to date of the speed at which sound travels in the quark–gluon plasma, offering new insights into this extremely hot state of matter.
The Large Hadron Collider hasn’t seen any new particles since the discovery of the Higgs boson in 2012. Here’s what researchers are trying to do about it.
A collaborative study conducted by Prof. Zhao Jin, Associate Prof. Zheng Qijing from the University of Science and Technology of China (USTC), and Prof. Hrvoje Petek from the University of Pittsburgh, has revealed the mechanisms behind the transition of bright-dark excitons in anatase TiO2. Their findings have been published in Proceedings of the National Academy of Sciences.
Understanding Excitons
Excitons, quasi-particles formed by the binding of electrons and holes in condensed matter systems via Coulomb interaction, exhibit distinct properties as bright and dark excitons. While bright excitons directly couple with light and play a pivotal role in light absorption, dark excitons, with their relatively longer lifetimes, hold significance in quantum information processing, Bose-Einstein condensation, and light-energy harvesting.
Directing magnetization with a low electric field is crucial for advancing effective spintronic devices. In spintronics, the characteristics of an electron’s spin or magnetic moment are leveraged for information storage. By modifying orbital magnetic moments through strain, it’s possible to manipulate electron spins, leading to an enhanced magnetoelectric effect for superior performance.
Japanese researchers, including Jun Okabayashi from the University of Tokyo, revealed a strain-induced orbital control mechanism in interfacial multiferroics. In multiferroic material, the magnetic property can be controlled using an electric field—potentially leading to efficient spintronic devices. The interfacial multiferroics that Okabayashi and his colleagues studied consist of a junction between a ferromagnetic material and a piezoelectric material. The direction of magnetization in the material could be controlled by applying voltage.
Recent research has discovered that, in contrast to earlier assumptions, substantial quantities of aerosol particles are generated across extensive regions of the West Siberian taiga during spring. These findings indicate that rising temperatures can greatly influence the climate due to this phenomenon.
Aerosol particles significantly contribute to the Earth’s cooling process. They can impact the amount of sunlight that reaches the Earth’s surface either directly or indirectly by aiding in cloud formation. These particles originate from various gas molecules and are found all over the planet.
To understand the circumstances in which these particles are formed, researchers conduct measurements in various environments all over the world. For example, the Finnish flagship station SMEAR II has conducted measurements in the boreal forest for 25 years.
While atomic clocks are already the most precise timekeeping devices in the universe, physicists are working hard to improve their accuracy even further. One way is by leveraging spin-squeezed states in clock atoms.
Spin-squeezed states are entangled states in which particles in the system conspire to cancel their intrinsic quantum noise. These states, therefore, offer great opportunities for quantum-enhanced metrology since they allow for more precise measurements. Yet, spin-squeezed states in the desired optical transitions with little outside noise have been hard to prepare and maintain.
One particular way to generate a spin-squeezed state, or squeezing, is by placing the clock atoms into an optical cavity, a set of mirrors where light can bounce back and forth many times. In the cavity, atoms can synchronize their photon emissions and emit a burst of light far brighter than from any one atom alone, a phenomenon referred to as superradiance. Depending on how superradiance is used, it can lead to entanglement, or alternatively, it can instead disrupt the desired quantum state.
Electronics are based on electrical charges being transported from one place to another. Electrons move, current flows, and signals are transmitted by applying an electrical voltage. However, there is also another way to manipulate electronic currents and signals: using the properties of the spin—the intrinsic magnetic moment of the electron. This is called “spintronics,” and it has become an increasingly important field in contemporary electronic research.
An international research team involving TU Wien and the Czech Academy of Sciences has now achieved an important breakthrough. They have managed to switch the spins in an antiferromagnetic material using surface strain. This could lead to an important new line of research in electronic technologies. The research is published in the journal Advanced Functional Materials.
“There are different types of magnetism,” explains Sergii Khmelevskyi from the Vienna Scientific Cluster Research Center, TU Wien. “The best known is ferromagnetism. It occurs when the atomic spins in a material are all aligned in parallel. But there is also the opposite, antiferromagnetism. In an antiferromagnetic material, neighboring atoms always have opposite spins.” Their effects therefore cancel each other out and no magnetic force can be detected from the outside.
Does dark matter reside in a deformed mirror universe of our own, where rules are different and atoms failed to form?
