For decades, a theory in physics has postulated the existence of a mirror world whose interaction with our own reality is extremely feeble. The particles in this mirror universe are also thought to be candidates for dark matter. Researchers at the Paul Scherrer Institute PSI have now examined some 25 billion neutrons—thereby ruling out, with a very high degree of certainty, their disappearance into the mirror world. The research is published in the journal Physical Review Letters.
Researchers from Skoltech, together with colleagues from the N.D. Zelinsky Institute of Organic Chemistry and Westlake University, have experimentally demonstrated how the operating regime of a polariton laser changes with a gradual increase in cavity thickness.
From planning transportation networks to organizing massive datasets, many of society's most important challenges boil down to an optimization problem: finding the best solution among an enormous number of possibilities. As these problems increase in size and scope, however, the computational resources required to solve them can increase dramatically.
A shape that captured worldwide attention for solving a decades-old mathematical puzzle has returned to the spotlight. While the shape's properties allowed it to solve previous puzzles, little is known about its other associated properties, creating opportunities for further discovery. These unexplored properties may also help solve new physics mysteries, such as how to twist light into striking chiral patterns.
Quantum technologies are devices and systems that exploit the laws of quantum mechanics and could perform tasks that are difficult or impossible to tackle using their classical counterparts. These technologies process and store information using qubits (i.e., quantum bits), which can exist in a superposition of multiple states simultaneously.
Electronic motion sets the stage for virtually every light-induced process in nature, from the first step of a chemical reaction to the flow of charge in a solid. Yet these processes unfold so rapidly that they can be observed only with flashes of light lasting a few hundred attoseconds—billionths of a billionth of a second.
For most theories in physics, the order of operations has little impact on the result. When setting a dial to a certain position, for example, it doesn't matter whether it's turned clockwise or counterclockwise—the result will always be the same. Yet for non-Abelian gauge theories, order does matter. These theories underpin the Standard Model, but to test their more subtle predictions, researchers have so far relied on enormous particle accelerators.
Scientists have discovered a previously unknown law of geometry that explains why some growing surfaces, whether in nature or in engineered materials, suddenly stop being able to stay smooth and instead form dimples and folds. Until now, researchers believed they understood the geometric rules behind these shape changes, but this study reveals a new kind of "geometric frustration" that arises even when all the known rules are satisfied.
Most electronic memory storage devices require the ability to trap large numbers of electrons for each bit of memory. In an ideal world, however, it would take only one electron. This would reduce space requirements and power consumption for devices. Now, a team in China has realized this goal with an ultrathin device capable of minimizing the stray capacitance that plagued earlier attempts. The new study, published in Science, describes how this novel device has overcome challenges in implementing the single-electron design.
Resolving a long-standing problem in semiconductor physics and optoelectronics, a team of researchers from Skoltech—a VEB.RF group institution—and their colleagues from ITMO University and HSE University have for the first time demonstrated direct electrical pumping of a polariton laser based on a solution-processed halide perovskite microcrystal. Published in Nature, this solution to a decades-long technological challenge ushers in inexpensive nonepitaxial laser diodes operating under continuous electric current. These could be used in optical sensing and spectroscopy, high-speed computing and energy-efficient neuromorphic computing.
Mechanical strain is one of the most common tools used to tailor the properties of materials. In piezoelectric materials, stretching or compressing a crystal generates an electrical polarization. In piezomagnetic materials, it induces magnetization. Researchers at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) and the University of Oxford have now discovered that mechanical strain also induces chirality in non-chiral crystals, opening a new direction to control this property on demand and potentially imprint chiral electronic properties. This work has just been published in Nature.
Electrons zipping through transistors, powering the screens on our smartphones. Light zooming from distant stars to Earth, moving faster than anything else in the universe. Protons enabling MRI machines to analyze people's injuries.
Bose–Einstein condensates are states of matter that form when particles called bosons are cooled to temperatures that are only a fraction of a degree above absolute zero (i.e., 0 Kelvin [-460°F]). In these states, particles occupy the same quantum state and exhibit interesting collective behaviors, essentially behaving as if they were a single "super-particle."
Full-color displays normally require separate red, green and blue light emitters. A team from the University of Osaka and Ritsumeikan University has demonstrated another approach: a single light-emitting layer that produces several colors when electrically powered at room temperature. The study was published in Applied Physics Letters.
Where do gold, platinum and uranium come from? This question has fascinated astrophysicists and nuclear physicists for decades. A research team from Technische Universität Darmstadt has now taken an important step toward understanding the origin of heavy elements. Their findings are published in Physical Review Letters.
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