Optical imaging and characterization of weakly scattering phase objects, such as isolated cells, bacteria and thin tissue sections frequently used in biological research and medical applications, have been of significant interest for decades. Due to their optical properties, when these 'phase objects' are illuminated with a light source, the amount of scattered light is usually much less than the light directly passing through the specimen, resulting in a poor image contrast using traditional imaging methods. This low image contrast can be overcome using, for example, chemical stains or fluorescent tags. However, these external labeling or staining methods are often tedious, costly and involve toxic chemicals.
Information in computers is transmitted through semiconductors by the movement of electrons and stored in the direction of the electron spin in magnetic materials. To shrink devices while improving their performance—a goal of an emerging field called spin-electronics ("spintronics")—researchers are searching for unique materials that combine both quantum properties. Writing in Nature Materials, a team of chemists and physicists at Columbia finds a strong link between electron transport and magnetism in a material called chromium sulfide bromide (CrSBr).
Mysterious fast radio bursts release as much energy in one second as the Sun pours out in a year and are among the most puzzling phenomena in the universe. Now researchers at Princeton University, the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) and the SLAC National Accelerator Laboratory have simulated and proposed a cost-effective experiment to produce and observe the early stages of this process in a way once thought to be impossible with existing technology.
Unlike fictional laser swords, real laser beams do not interact with each other when they cross—unless the beams meet within a suitable material allowing for nonlinear light-matter interaction. In such a case, wave mixing can give rise to beams with changed colors and directions.
An international research collaboration has discovered how to exploit certain defects to protect confined energy in acoustics systems. Their experimental approach provides a versatile platform to create at-will defects for further theoretical validation and to improve control of waves in other systems, such as light, according to principal investigator Yun Jing, associate professor of acoustics and of biomedical engineering at Penn State.
High temperature superconductivity is something of a holy grail for researchers studying quantum materials. Superconductors, which conduct electricity without dissipating energy, promise to revolutionize our energy and telecommunication power systems. However, superconductors typically work at extremely low temperatures, requiring elaborate freezers or expensive coolants. For this reason, scientist have been relentlessly working on understanding the fundamental mechanisms at the base of high-temperature superconductivity with the ultimate goal to design and engineer new quantum materials superconducting close to room temperature.
As physicists delve deeper into the quantum realm, they are discovering an infinitesimally small world composed of a strange and surprising array of links, knots and winding. Some quantum materials exhibit magnetic whirls called skyrmions—unique configurations described as "subatomic hurricanes." Others host a form of superconductivity that twists into vortices.
Some metals are in liquid form, the prime example being mercury. But there are also enormous quantities of liquid metal in the Earth's core, where temperatures are so high that part of the iron is molten and undergoes complex flows. A team at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has now simulated a similar process in the laboratory and made a surprising discovery: Under certain circumstances, the flow of liquid metal is far more turbulent than expected—and this has a significant impact on heat transport. The research is published in Physical Review Letters.
Researchers at Northeastern have discovered a new quantum phenomenon in a specific class of materials, called antiferromagnetic insulators, that could yield new ways of powering "spintronic" and other technological devices of the future.
A research team from the Institute of Mechanics of the Chinese Academy of Sciences has revealed the multi-scale characteristics of helicity in wall-bounded turbulent flows.
Researchers from PSI's Spectroscopy of Quantum Materials group together with scientists from Beijing Normal University have solved a puzzle at the forefront of research into iron-based superconductors: the origin of FeSe's electronic nematicity. Using Resonant inelastic X-ray scattering (RIXS) at the Swiss Light Source (SLS), they discovered that, surprisingly, this electronic phenomenon is primarily spin driven. Electronic nematicity is believed to be an important ingredient in high-temperature superconductivity, but whether it helps or hinders it is still unknown. Their findings are published in Nature Physics.
Bose-Einstein condensates (BECs), created in ultracold bosonic atoms and degenerate quantum gases, are a macroscopic quantum phenomenon and are considered as a single particle in mean-filed theory. By preparing the BECs or ultracold atomic gases onto optical lattices, the existence of nonlinear matter-wave solitons and their dynamics and simulation in condensed-matter physics can be investigated.
Ever since the discovery of the quantum Hall effect (Nobel Prize 1985), symmetry has been the guiding principle in the search for topological materials. Now an international team of researchers from Germany, Switzerland, and the U.S. has introduced an alternative guiding principle, "quasi-symmetry," which leads to the discovery of a new type of topological material with great potential for applications in spintronics and quantum technologies. This work has been published in Nature Physics.
In order to achieve a fusion power plant, it is necessary to stably confine a plasma of more than 100 million degrees Celsius in a magnetic field and maintain it for a long time. A research group led by Assistant Professor Naoki Kenmochi, Professor Katsumi Ida, and Associate Professor Tokihiko Tokuzawa of the National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences (NINS), Japan, using measuring instruments developed independently and with the cooperation of Professor Daniel J. den Hartog of the University of Wisconsin, USA, discovered for the first time that turbulence moves faster than heat when heat escapes in plasmas in the Large Helical Device (LHD). One characteristic of this turbulence makes it possible to predict changes in plasma temperature, and it is expected that observation of turbulence will lead to the development of a method for real-time control of plasma temperature in the future.
In recent years, physicists have carried out extensive studies focusing on quantum technology and quantum many-body systems. Two out-of-equilibrium dynamical processes that have attracted particular attention in this field are quantum thermalization and information scrambling.
Metamaterials—artificial media with tailored subwavelength structures—have now encompassed a broad range of novel properties that are unavailable in nature. This field of research has stretched across different wave platforms, leading to the discovery and demonstration of a wealth of exotic wave phenomena. Most recently, metamaterial concepts have been extended to the temporal domain, paving the way to completely new concepts for wave control, such as nonreciprocal propagation, time-reversal, new forms of optical gain and drag.
New research suggests an unseen "mirror world" of particles that interacts with our world only via gravity that might be the key to solving a major puzzle in cosmology today—the Hubble constant problem.
Quantum physicists aim to scale the number of qubits during quantum computing, while maintaining high-fidelity quantum gates; this is a challenging task due to the precise frequency requirements that accompany the process. Superconducting quantum processors with more than 50 qubits are currently actively available and these fixed frequency transmons are attractive due to their long coherence and noise immunity. A transmon is a type of a superconducting charge qubit designed to have reduced sensitivity to charge noise. In a new report now published in Science Advances, Eric J. Zhang and a team of scientists at IBM Quantum, IBM T.J. Watson Research Centre, New York, U.S., used laser annealing to selectively tune transmon qubits into the desired frequency patterns. The research team achieved a tuning precision of 18.5 MHz, without any measurable impact on quantum coherence, and envision facilitating selective annealing in this way to play a central role in fixed-frequency architectures.
Controlling strong electromagnetic fields on nanoparticles is the key to triggering targeted molecular reactions on their surfaces. Such control over strong fields is achieved via laser light. Although laser-induced formation and breaking of molecular bonds on nanoparticle surfaces have been observed in the past, nanoscopic optical control of surface reactions has not yet been achieved. An international team led by Dr. Boris Bergues and Prof. Matthias Kling at Ludwig-Maximilians-Universitat (LMU) and the Max Planck Institute of Quantum Optics (MPQ) in collaboration with Stanford University has now closed this gap. The physicists determined for the first time the location of light-induced molecular reactions on the surface of isolated silicon dioxide nanoparticles using ultrashort laser pulses.
The ALICE collaboration at the Large Hadron Collider (LHC) has made the first direct observation of the dead-cone effect—a fundamental feature of the theory of the strong force that binds quarks and gluons together into protons, neutrons and, ultimately, all atomic nuclei. In addition to confirming this effect, the observation, reported in a paper published today in Nature, provides direct experimental access to the mass of a single charm quark before it is confined inside hadrons.
When atoms interact with each other, they behave as a whole rather than individual entities. That can give rise to synchronized responses to inputs, a phenomenon that, if properly understood and controlled, may prove useful for developing light sources, building sensors that can take ultraprecise measurements, and understanding dissipation in quantum computers.
Over the past few years, many physicists and material scientists have been investigating superconductivity, the complete disappearance of electrical resistance observed in some solid materials. Superconductivity has so far been primarily observed in materials that are cooled to very low temperatures, typically below 20 K.
A team of researchers affiliated with several institutions in China has found that quantum key distribution (QKD) networks can be used to accurately measure ground vibration. In their paper published in the journal Physical Review Letters, the group describes their implementation of a twin-field, fiber-based QKD network over a distance of 658 km. They also determined that the network could be used as a means for sensing ground vibrations associated with earthquakes or landslides.
Compact and lightweight metasurfaces—which use specifically designed and patterned nanostructures on a flat surface to focus, shape and control light—are a promising technology for wearable applications, especially virtual and augmented reality systems. Today, research teams painstakingly design the specific pattern of nanostructures on the surface to achieve the desired function of the lens, whether that be resolving nanoscale features, simultaneously producing several depth-perceiving images or focusing light regardless of polarization.
Researchers have developed a new metasurface-based device that can produce multiple distinct holographic images depending on the surrounding medium and the wavelength of light used. The ability to store information that is only retrievable with the right set of keys—such as a certain light wavelength combined with wet conditions—could be further developed to design simple yet effective encryption devices.
If you have ever watched a bird land on a tree branch, you may have noticed that it rapidly pitches its wings upward at a high angle to execute a smooth landing. However, for some birds, they land by folding their wings as they perch instead, creating a sweeping motion as they decelerate.
Physicists at EPFL, within a large European collaboration, have revised one of the fundamental laws that has been foundational to plasma and fusion research for over three decades, even governing the design of megaprojects like ITER. The update shows that we can actually safely use more hydrogen fuel in fusion reactors, and therefore obtain more energy than previously thought.
