The largest particle detector of its kind has failed to turn up any hints of dark matter, despite searching for about a year.
Known as XENON1T, the experiment is designed to detect elusive dark matter particles, which are thought to make up most of the matter in the cosmos. Physicists don’t know what dark matter is. One of the most popular explanations is a particle called a WIMP, short for weakly interacting massive particle. XENON1T searches for WIMPs crashing into atomic nuclei in 1,300 kilograms of chilled liquid xenon. But XENON1T saw no such collisions. The particles’ absence further winnowed down their possible hiding places by placing new limits on how frequently WIMPs can interact with nuclei depending on their mass.
Researchers describe the results May 28 in two talks, one at Gran Sasso National Laboratory in Italy, where XENON1T is located, and the other at the European particle physics lab CERN in Geneva. XENON1T...
As Reported by Syl Kacapyr at Cornell University:
While defects in a diamond are mostly undesirable, certain defects are a quantum physicist’s best friend, having the potential to store bits of information that could one day be used in a quantum computing system.
Applied physicists at Cornell have demonstrated a technique for engineering some of the key optical properties of those defects, providing a new tool for exploring quantum mechanics.
A group of researchers led by Greg Fuchs, professor of applied and engineering physics, have become the first to use vibrations produced by a resonator to help stabilize those optical properties, forcing the diamond’s electrons into an excited orbital state. The research is detailed in the paper “Orbital State Manipulation of a Diamond Nitrogen-Vacancy Center Using a Mechanical Resonator,” published April 17 in the journal Physical Review Letters.
Much like a computer’s transistors record binary information by...
Metamaterials researchers at Duke University have demonstrated the design and construction of a thin material that can control the redirection and reflection of sound waves with almost perfect efficiency.
While many theoretical approaches to engineer such a device have been proposed, they have struggled to simultaneously control both the transmission and reflection of sound in exactly the desired manner, and none have been experimentally demonstrated.
The new design is the first to demonstrate complete, near-perfect control of sound waves and is quickly and easily fabricated using 3-D printers. The results appear online April 9 in Nature Communications.
"Controlling the transmission and reflection of sound waves this way was a theoretical concept that did not have a path to implementation—nobody knew how to design a practical structure using these ideas," said Steve Cummer, professor of electrical and computer...
In 2015, after 85 years of searching, researchers confirmed the existence of a massless particle called the Weyl fermion. With the unique ability to behave as both matter and anti-matter inside a crystal, this quasiparticle is like an electron with no mass. The story begun in 1928 when Dirac proposed an equation for the foundational unification of quantum mechanics and special relativity in describing the nature of the electron. This new equation suggested three distinct forms of relativistic particles: the Dirac, the Majorana, and the Weyl fermions. And recently, an analog of Weyl fermions has been discovered in certain electronic materials exhibiting a strong spin orbit coupling and topological behavior. Just as Dirac fermions emerge as signatures of topological insulators, in certain types of semimetals, electrons can behave like Weyl fermions.
These Weyl fermions are what can be...
Stochastic processes are ubiquitous in nature. Also known as random processes, they can take multiple forms like a random walk, or a game of chance. Their studies have played a pivotal role in the development of modern physics starting with Langevin and the Brownian motion well illustrated by pollen grain floating in water. Recent advances in measurement precision and resolution have extended the framework of Brownian motion to unprecedented space-time scales and to a wider variety of systems, including atomic diffusion in optical lattices and spin diffusion in liquids. Studies of such systems are providing insights into the mechanisms and interactions responsible for stochasticity.
For example, membrane fluctuations are also a purview of Brownian motion. Where it becomes really interesting is when properly understood, the random membrane fluctuations can be usefully exploited for energy harvesting. From a stochastic...
Finding a new energy storage material is a great challenge and sodium is showing great promise. Being one of the two main ingredients in the salt, it is very abundant, non-toxic and cheap. However, it is very difficult to produce a sodium based battery. The problem is, when exposed to air, the metals in a sodium battery’s cathode can be oxidized, decreasing the performance of the battery or even rendering it completely inactive.
In the last years, research on the development of sodium-ion batteries have been making great progress in terms of performance utilizing layered transition-metal oxides and polyanions. It appears that the sodium compounds can be promising compared with their lithium analogs. Combining, the layered metal oxides with polyanions will offer a good compromise between high energy densities and stable cycle life.
The EM drive – a radio frequency (RF) resonant cavity thruster – appears to produce an ‘impossible’ thrust. Impossible – in that it apparently violates Newtons third law of motion: “For every action, there is an equal and opposite reaction.” Now in a recent paper by a group of Portuguese physicists, led by Prof. Jose Croca from the Center for Philosophy of Sciences at the University of Lisbon, present a possible explanation for this observed ‘impossible’ thrust.
The EM drive was first proposed in 2001 by British inventor Roger Sawyer and has subsequently been tested by numerous groups around the world alongside possible explanations for its propulsion. However, still a hot topic of debate, a consensus on the level of thrust and an explanation for the thrust has not been found.
Croca and his team hope to change this through their explanation...
Recently, electromagnetic radiation in the terahertz (THz) frequency range has emerged as one of the most promising imaging techniques for a variety of applications in science and engineering. The potential and suitability of the THz technology for practical applications such as the nondestructive testing field has been released by the recent progress in producing efficient sources and detectors. Thanks to the development of ultra-fast components in both photonics and electronics, the situation is evolving rapidly.
THz waves, residing at a relatively unexplored region between the microwave and infrared, roughly 0.1-10THz, is one of the last frontiers in the electromagnetic spectrum. Unlike X-ray, THz is a non-ionizing radiation. It causes no known harm to the human body and the materials being examined. Moreover, THz can penetrate many common gases, non-polar liquids, and...
Metamaterials are a class of super-materials with remarkable characteristics. Metamaterials have been engineered to bend and shape light, providing an effective invisibility cloak.
The EmDrive, originally developed by Roger Shawyer at SPR Ltd., is a propellant-free microwave thruster that produces acceleration via an electromagnetic cavity without need for traditional fuel sources. After several successful experimental demonstrations of the EmDrive’s ability to produce thrust by NASA’s Eagleworks laboratory, several researchers are using the quantum mechanical model of Pilot Wave theory to describe how the engine interacts with the quantum vacuum to produce thrust.
Video: https://www.youtube.com/watch?v=WIyTZDHuarQ&feature=emb_title
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A class known as left-handed metamaterials have been predicted to produce levitation via a repulsive force from the quantum vacuum:
As eluded to in a previous commentary...