International Conference on Condensed Matter Physics

International Conference on Condensed Matter Physics Dark Energy, Dark Matter  In the early 1990s, one thing was fairly certain about the expansion of the universe. It might have enough energy density to stop its expansion and recollapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. Granted, the slowing had not been observed, but, theoretically, the universe had to slow. The universe is full of matter and the attractive force of gravity pulls all matter together. Then came 1998 and the Hubble Space Telescope (HST) observations of very distant supernovae that showed that, a long time ago, the universe was actually expanding more slowly than it is today. So the expansion of the universe has not been slowing due to gravity, as everyone thought, it has been accelerating. No one expected this, no one knew how to explain it. But something was causing it. Eventually theorists came up with three so...

  International Conference on Condensed Matter Physics A tool for estimating the local entropy production rate of a system enables the visualization and quantification of the out-of-equilibrium regions of an active-matter system. A movie of a molecule jostling around in a fluid at equilibrium looks the same when played forward and backward. Such a movie has an “entropy production rate”—the parameter used to quantify this symmetry—of zero; most other movies have a nonzero value, meaning the visualized systems are out of equilibrium. Researchers know how to compute the entropy production rate of simple model systems. But measuring this parameter in experiments is an open problem. Now Sungham Ro of the Technion-Israel Institute of Technology, Buming Guo of New York University, and colleagues have devised a method for making local measurements of the entropy production rate [1]. They demonstrate the technique using simulations and bacteria observations (Fig. 1). The method, which inv...

International Conference on Condensed Matter Physics A team of researchers has developed a new acoustic waveguide based on the mathematical concept of topology, which will lead to reduced energy consumption in many everyday electronic devices. Details of their innovation were published in the journal Physical Review Applied on January 3, 2023. As their name implies, surface acoustic waves (SAW) are a type of acoustic wave where the vibration magnitude is focused on a material's surface. SAWs can be excited and detected on piezoelectric substrates, crystals with the ability to generate electricity when compressed or vibrated. Electrical components, known as SAW devices, make use of this and provide frequency filtering and sensing in common electronic devices such as mobile phones and touch sensors. But one drawback of SAW devices is that they consume a lot of energy, and thus are a drain on battery life. The team, which comprised Yoichi Nii and Yoshinori Onose from the Institute fo...

International Conference on Condensed Matter Physics In a historic achievement, University of Rochester researchers have created a superconducting material at both a temperature and pressure low enough for practical applications. "With this material, the dawn of ambient superconductivity and applied technologies has arrived," according to a team led by Ranga Dias, an assistant professor of mechanical engineering and physics. In a paper in Nature, the researchers describe a nitrogen-doped lutetium hydride (NDLH) that exhibits superconductivity at 69 degrees Fahrenheit (20.5 degrees Celsius) and 10 kilobars (145,000 pounds per square inch, or psi) of pressure. Although 145,000 psi might still seem extraordinarily high (pressure at sea level is about 15 psi), strain engineering techniques routinely used in chip manufacturing, for example, incorporate materials held together by internal chemical pressures that are even higher. Scientists have been pursuing this breakthrough in c...

International Conference on Condensed Matter Physics Most materials derive their macroscopic properties from their microscopic structure. A steel rod is hard, for instance, because its atoms form a repeating crystalline pattern that remains static over time. Water parts around your foot when you dip it into a lake because fluids don’t have that structure; their molecules move around randomly. Then there’s glass, a strange in-between substance that has puzzled physicists for decades. Take a snapshot of the molecules in glass, and they’ll appear disordered just like a liquid’s. But most of the molecules barely move, making the material rigid like a solid. Glass is formed by cooling certain liquids. But why the molecules in the liquid slow down so dramatically at a certain temperature, with no obvious corresponding change in their structural arrangement — a phenomenon known as the glass transition — is a major open question. Now, researchers at DeepMind, a Google-owned artificial inte...

  International Conference on Condensed Matter Physics The research, published in the journal Physical Review Applied in February, uses a technique called nuclear magnetic resonance spectroscopy to measure the distribution of water in a material. The results could help researchers understand how moisture behaves in a variety of contexts -- from humidity in a house's insulation to drying clothes after washing. "With all these tools, we are able to effectively determine the law of absorption that has been so unknown," said Philippe Coussot, a research engineer at Gustave Eiffel University in France. "This basic approach is just the first step to be able to more systematically determine the real kinetic equation for absorption." In a wet piece of fabric, water can either be bound to the structure of the fabric or circulate as vapor in between the weave. Coussot and colleagues put samples of wet fabric into open-topped containers and exposed them to dry air flows. T...

International Conference on Condensed Matter Physics  A research team says that they have made a material that conducts electricity without resistance at near-ambient conditions. The community has heard it before. J. Adam Fenster/Univ. of Rochester A microscope image of a roughly 1-mm-diameter sample of lutetium hydride. Researchers claim that when doped with nitrogen this material can superconduct at room temperature and near-ambient pressure. On Tuesday, when Ranga Dias announced in a talk that his team has fabricated a room-temperature superconductor, not one person uttered a word. Speaking at the APS March Meeting in Las Vegas, the University of Rochester physicist cast the claimed accomplishment as the culmination of a more-than-a-century-long hunt for the condensed-matter “holy grail”: a material that conducts electrons with zero resistance at ambient temperatures. Physicists have long touted the technological revolutions that a room-temperature superconductor might spark, an...