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Category: particle physics – Page 305

Resistive switching random-access memories (RRAMs) integrate information storage and processing into the same device, enabling faster and more energy-efficient computing. However, RRAMs are challenging to fabricate and suffer from inconsistent on-off switching. Now Zheng Jie Tan, Vrindaa Somjit, and collaborators at the Massachusetts Institute of Technology have discovered that adding dopants to the RRAMs dramatically improves their performance and the yield of their fabrication [1]. The researchers say their results provide an additional “knob” to optimize RRAMs, helping position them as one of the leading technologies for so-called in-memory computation.

An RRAM comprises an insulating material sandwiched between two metallic layers. The bits are defined by the amount of current that passes through the device via conduction paths in the insulator under a voltage. If the voltage is strong enough, it can induce the formation or destruction of conduction paths, thus controlling information processing.

While fabricating their device, the researchers added electronegative dopants, such as gold atoms, to the insulating material. The electron redistribution induced by the dopants facilitated the formation of conduction paths, which became more stable and showed increased on-off switching consistency compared with their undoped counterparts. Moreover, doped RRAMs were consistently fabricated with conducting paths already established before the device was used. Undoped RRAMs are often fabricated without such paths, and the postfabrication process required to create them—“electroforming,” involving the application of a very strong voltage—can result in irreparable device damage.

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Researchers can now predict exactly how soap molecules spread across a body of water, an everyday but surprisingly complex process.

When a tiny drop of soapy water falls onto a pool of liquid, its contents spread out over the pool’s surface. The dynamics of this spreading depend on the local concentration of soap—which varies in time and is difficult to predict—at each point across the entire pool’s surface. Now Thomas Bickel of the University of Bordeaux in Talence, France, and Francois Detcheverry of the University of Lyon, France, have derived an exact time-dependent solution for these distributions [1]. The solution reveals surprisingly rich behaviors in this everyday phenomenon.

The duo considered a surfactant-laden drop spreading over the surface of a deep pool of fluid. Researchers have previously shown that the equations governing the transport of the surfactant particles can be mapped to a partial differential equation known as the Burgers’ equation, which was initially developed to describe flows in turbulent fluids.

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Discovery of intriguing material behavior at small scales could reduce energy demands for computing.

As become smaller and smaller, the materials that power them need to become thinner and thinner. Because of this, one of the key challenges scientists face in developing next-generation energy-efficient electronics is discovering materials that can maintain special electronic properties at an ultrathin size.

Advanced materials known as ferroelectrics present a promising solution to help lower the power consumed by the ultrasmall electronic devices found in cell phones and computers. Ferroelectrics—the electrical analog to ferromagnets—are a class of materials in which some of the atoms are arranged off-center, leading to a spontaneous internal electric charge or polarization. This internal polarization can reverse its direction when scientists expose the material to an external voltage. This offers great promise for ultralow-power microelectronics.

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Gravitational waves are invisible to the naked eye, but can be detected with instruments such as the Large Interferometer Gravitational Wave Observatory (LIGO) in Pasadena, California. So, after LIGO detected the first blast of waves from the colliding stars in 2017, astronomers around the world trained their telescopes on the merger to learn whatever they could about it. Before long, astronomers saw visible evidence of a high-speed jet of particles, blazing out of the collision site and lighting up globs of matter that had been ejected by the stars.

In their new paper, astronomers analyzed that jet with NASA’s Hubble Space Telescope, the European Space Agency’s Gaia space observatory and several additional radio telescopes on Earth. With these observations, the team calculated both the actual speed of the jet, and the perceived physics-defying speed.

The beyond-light-speed illusion arises from the difference in speed between the particles in the jet, and the light particles (or photons) that they emit. Because the jet’s particles move nearly as fast as the light they emit, it can appear as though particles in the early part of the jet are arriving at Earth at nearly the same time as photons in the later stages of the jet — making it appear as though the jet is actually moving faster than the speed of light.

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In quantum physics, Fermi’s golden rule, also known as the golden rule of time-dependent perturbation theory, is a formula that can be used to calculate the rate at which an initial quantum state transitions into a final state, which is composed of a continuum of states (a so-called “bath”). This valuable equation has been applied to numerous physics problems, particularly those for which it is important to consider how systems respond to imposed perturbations and settle into stationary states over time.

Fermi’s golden rule specifically applies to instances in which an initial is weakly coupled to a continuum of other final states, which overlap its energy. Researchers at the Centro Brasileiro de Pesquisas Físicas, Princeton University, and Universität zu Köln have recently set out to investigate what happens when a quantum state is instead coupled to a set of discrete final states with a nonzero mean level spacing, as observed in recent many-body physics studies.

“The decay of a quantum state into some continuum of final states (i.e., a ‘bath’) is commonly associated with incoherent decay processes, as described by Fermi’s golden rule,” Tobias Micklitz, one of the researchers who carried out the study, told Phys.org. “A standard example for this is an excited atom emitting a photon into an infinite vacuum. Current date experimentations, on the other hand, routinely realize composite systems involving quantum states coupled to effectively finite size reservoirs that are composed of discrete sets of final states, rather than a continuum.”

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Immunizing bees against pesticides.

‘We wanted to develop a strategy to detoxify managed pollinators and found we can do it by incorporating it into their food, senior author Minglin Ma, a biomaterials engineer at Cornell University told Chemistry World.

“Managed bee colonies are constantly in need of being replenished due to losses. This relieves the stress for beekeepers to meet the ever-increasing demand for pollination,” James Webb, also a co-author of the study, told Salon by email.

The pollen-like particle: The team created a pollen-sized microparticle with an enzyme designed to detoxify organophosphate pesticides. Usually, the bee’s crop (stomach) would break down the enzymes. But the researchers created a protective shell that allows it to pass through the crop unscathed.

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Quantum physics is strange. At least, it is strange to us, because the rules of the quantum world, which govern the way the world works at the level of atoms and subatomic particles (the behavior of light and matter, as the renowned physicist Richard Feynman put it), are not the rules that we are familiar with — the rules of what we call “common sense.”

The quantum rules, which were mostly established by the end of the 1920s, seem to be telling us that a cat can be both alive and dead at the same time, while a particle can be in two places at once. But to the great distress of many physicists, let alone ordinary mortals, nobody (then or since) has been able to come up with a common-sense explanation of what is going on. More thoughtful physicists have sought solace in other ways, to be sure, namely coming up with a variety of more or less desperate remedies to “explain” what is going on in the quantum world.

These remedies, the quanta of solace, are called “interpretations.” At the level of the equations, none of these interpretations is better than any other, although the interpreters and their followers will each tell you that their own favored interpretation is the one true faith, and all those who follow other faiths are heretics. On the other hand, none of the interpretations is worse than any of the others, mathematically speaking. Most probably, this means that we are missing something. One day, a glorious new description of the world may be discovered that makes all the same predictions as present-day quantum theory, but also makes sense. Well, at least we can hope.

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Quantum science has not only deepened human understanding of the structure of matter and its microscopic interactions, but also introduced a new paradigm of computing and information science—quantum computing and quantum simulation. Quantum informatics research has won the 2022 Nobel Prize in Physics.

Among many and simulation platforms, Rydberg Atom Arrays is considered the most promising system to show quantum superiority among many programmable quantum simulator platforms in recent years due to its largest number of qubits and highest experimental accuracy.

Such optical lattices consist of individual neutral alkaline-earth atoms with significant dipole moments trapped in arrays of microscopic dipole traps, which can be optically moved at will to make desired lattice geometry. Each atom can be excited to its Rydberg state, and a pair of excited states interact through their dipole moments via a long-range interaction.

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Quantum entanglement is the binding together of two particles or objects, even though they may be far apart – their respective properties are linked in a way that’s not possible under the rules of classical physics.

It’s a weird phenomenon that Einstein described as “spooky action at a distance”, but its weirdness is what makes it so fascinating to scientists. In a 2021 study, quantum entanglement was directly observed and recorded at the macroscopic scale – a scale much bigger than the subatomic particles normally associated with entanglement.

The dimensions involved are still very small from our perspective – the experiments involved two tiny aluminum drums one-fifth the width of a human hair – but in the realm of quantum physics they’re absolutely huge.

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A team of researchers from the University of Warsaw in Poland, the Institute Pascal CNRS in France, the Military University of Technology in Poland and the British University of Southampton has shown that it is possible to control the so-called exceptional points. For the first time, physicists also observed the annihilation of exceptional points from different degeneracy points. You can read about the discovery that may contribute to the creation of modern optical devices in the latest Nature Communications.

The universe around us is made of , most of which have their antiparticles. When a particle and an antiparticle, that is, matter and antimatter, meet each other, annihilation occurs. Physicists have long been able to produce quasiparticles and quasiantiparticles—elementary excitations: charge, vibration, energy—trapped in matter, most often in crystals or liquids.

“The world of quasiparticles can be very complicated, although paradoxically, the quasiparticles themselves help simplify the description of quantum phenomena,” explains Jacek Szczytko from the Faculty of Physics at the University of Warsaw.

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