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Category: quantum physics – Page 459

Quantum computers are promising computing machines that perform computations leveraging the collective properties of quantum physics states. These computers could help to tackle many computational problems that are currently intractable with conventional computers.

Despite their promise, fabricating quantum computers on a large-scale is currently very challenging, as a full-scale quantum computer integrates millions of qubits. To ensure that they can be produced using industrial semiconductor manufacturing processes, quantum device engineers have been trying to create quantum computers based on silicon quantum dots.

Nonetheless, existing quantum computers have been primarily fabricated using and conventional lift-off processes. This greatly limits their production rates, as both these processes only yield a few properly functioning devices at a time.

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Polaritons are quasiparticles that are formed when photons couple strongly with excitations of matter. These quasi-particles, which are half-light and half-matter, underpin the functioning of a wide range of emergent photonic quantum systems, including semiconductor-based nanophotonic devices and circuit quantum electrodynamic systems.

Researchers at Stony Brook University have recently introduced a novel polariton system in which the matter excitation is replaced by an atom in an optical lattice and the photon by an atomic matter wave. This system, introduced in a paper published in Nature Physics, results in matter-wave polaritons, and could open interesting possibilities for the study of polaritonic quantum matter.

“A few years ago, we became interested in the idea of using ultracold atoms to simulate the dynamical behavior of ,” Dr. Dominik Schneble, head of the team of researchers who carried out the study, told Phys.org. “It turns out that it is possible to build an artificial atom that spontaneously emits matter waves, in much the same way as an atom spontaneously emits a photon (as described by the so-called Weisskopf-Wigner model).”

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Ron FriedmanThink outside the box. Most people don’t need a car for the sake of having a car.

Most people need a comfortable, quick and cheap way of going from A to B. So, Robotaxi could be the ideal solution for most people most of the time.… See more.

Jerry AndersonProbably not, because new batteries that contain other elements, I think they are saying Sulfur-Lithium batteries are more efficient last longer, and don’t require recharging as often… There are bound to be other breakthroughs.

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Shubham Ghosh Roy shared a link.

Continue reading “Infrared Multiple Photon Dissociation Spectroscopy Confirms Reversible Water Activation in Mn+(H2O)n, n ≤ 8” | >

Researchers in Beijing have set a new quantum secure direct communication (QSDC) world record of 102.2 km (64 miles), smashing the previous mark of 18 km (11 miles), The Eurasian Times reported. Transmission speeds were extremely slow at 0.54 bits per second, but still good enough for text message and phone call encryption over a distance of 30 km (19 miles), wrote research lead Long Guilu in Nature. The work could eventually lead to hack-proof communication, as any eavesdropping attempt on a quantum line can be instantly detected.

QSDC uses the principal of entanglement to secure networks. Quantum physics dictates that entangled particles are linked, so that if you change the property of one by measuring it, the other will instantly change, too — effectively making hacking impossible. In theory, the particles stay linked even if they’re light-years apart, so such systems should work over great distances.

The same research team set the previous fiber record, and devised a “novel design of physical system with a new protocol” to achieve the longer distance. They simplified it by eliminating the “complicated active compensation subsystem” used in the previous model. “This enables an ultra-low quantum bit error rate (QBER) and the long-term stability against environmental noises.”

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One of the ways we can fully realize the potential of quantum computers is by basing them on both light and matter – this way, information can be stored and processed, but also travel at the speed of light.

Scientists have just taken a step closer to this goal, by successfully producing the largest hybrid particles of light and matter ever created.

These quasiparticles, known as Rydberg polaritons, were made with the help of a piece of stone containing cuprous oxide (Cu2O) crystals from an ancient deposit in Namibia, one of the few places in the world where cuprous oxide has been found in gemstone quality.

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The CMS collaboration at the Large Hadron Collider (LHC) has performed the most accurate ever measurement of the mass of the top quark—the heaviest known elementary particle. The latest CMS result estimates the value of the top-quark mass with an accuracy of about 0.22%. The substantial gain in accuracy comes from new analysis methods and improved procedures to consistently and simultaneously treat different uncertainties in the measurement.

The precise knowledge of the top-quark mass is of paramount importance to understand our world at the smallest scale. Knowing this heaviest as intimately as possible is crucial because it allows testing of the internal consistency of the mathematical description of all elementary particles, called the Standard Model.

For example, if the masses of the W boson and Higgs boson are known accurately, the top-quark mass can be predicted by the Standard Model. Likewise, using the top-quark and Higgs-boson masses, the W-boson mass can be predicted. Interestingly, despite much progress, the theoretical-physics definition of mass, which has to do with the effect of quantum-physics corrections, is still tough to pin down for the top quark.

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Superconductors are materials that conduct electrical current with practically no electrical resistance at all. This ability makes them extremely interesting and attractive for a plethora of applications such as loss-less power cables, electric motors and generators, as well as powerful electromagnets that can be used for MRI imaging and for magnetic levitating trains. Now, researchers from Nagoya University have detailed the superconducting nature of a new class of superconducting material, magic-angle twisted bilayer graphene.

For a material to behave as a superconductor, low temperatures are required. Most materials only enter the superconducting phase at extremely low temperatures, such as −270°C, which is lower than those measured in outer space. This severely limits their practical applications because such extensive cooling requires very expensive and specialized liquid helium cooling equipment. This is the main reason superconducting technologies are still in their infancy.

High temperature superconductors (HTS), such as some iron and copper-based examples, enter the superconducting phase above −200°C, a temperature that is more readily achievable using liquid nitrogen which cools down a system to −195.8°C. However, the industrial and commercial applications of HTS have been thus far limited. Currently known and available HTS materials are brittle ceramic materials that are not malleable and cannot be made into useful shapes like wires. In addition, they are notoriously difficult and expensive to manufacture. This makes the search for new superconducting materials critical and a strong focus of research for physicists like Prof. Hiroshi Kontani and Dr. Seiichiro Onari from the Department of Physics, Nagoya University.

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