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Category: quantum physics

Scientists on the hunt for an unconventional kind of superconductor have produced the most compelling evidence to date that they’ve found one. In a pair of papers, researchers at the University of Maryland’s (UMD) Quantum Materials Center (QMC) and colleagues have shown that uranium ditelluride (or UTe2 for short) displays many of the hallmarks of a topological superconductor—a material that may unlock new ways to build quantum computers and other futuristic devices.

“Nature can be wicked,” says Johnpierre Paglione, a professor of physics at UMD, the director of QMC and senior author on one of the papers. “There could be other reasons we’re seeing all this wacky stuff, but honestly, in my career, I’ve never seen anything like it.”

All superconductors carry electrical currents without any resistance. It’s kind of their thing. The wiring behind your walls can’t rival this feat, which is one of many reasons that large coils of superconducting wires and not normal copper wires have been used in MRI machines and other scientific equipment for decades.

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As pervasive as they are in everyday uses, like encryption and security, randomly generated digital numbers are seldom truly random.

So far, only bulky, relatively slow quantum random generators (QRNGs) can achieve levels of randomness on par with the basic laws of quantum physics, but researchers are looking to make these devices faster and more portable.

In Applied Physics Letters, scientists from China present the fastest real-time QRNG to date to make the devices quicker and more portable. The device combines a state-of-the-art photonic integrated with optimized real-time postprocessing for extracting randomness from quantum entropy source of vacuum states.

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Quantum mechanics deals with the behavior of the Universe at the super-small scale: atoms and subatomic particles that operate in ways that classical physics can’t explain. In order to explore this tension between the quantum and the classical, scientists are attempting to get larger and larger objects to behave in a quantum-like way.

In the case of this particular study, the object in question is a tiny glass nanosphere, 100 nanometers in diameter – about a thousand times smaller than the thickness of a human hair. To our minds that’s very, very small, but in terms of quantum physics, it’s actually rather huge, made up to 10 million atoms.

Pushing such a nanosphere into the realm of quantum mechanics is actually a huge achievement, and yet that’s exactly what physicists have now accomplished.

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Electronic circuits that compute and store information contain millions of tiny switches that control the flow of electric current. A deeper understanding of how these tiny switches work could help researchers push the frontiers of modern computing.

Now scientists have made the first snapshots of atoms moving inside one of those switches as it turns on and off. Among other things, they discovered a short-lived state within the switch that might someday be exploited for faster and more energy-efficient computing devices.

The research team from the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University, Hewlett Packard Labs, Penn State University and Purdue University described their work in a paper published in Science today.

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The Google Quantum AI team has found that adding logical qubits to the company’s quantum computer reduced the logical qubit error rate exponentially. In their paper published in the journal Nature, the group describes their work with logical qubits as an error correction technique and outline what they have learned so far.

One of the hurdles standing in the way of the creation of usable quantum computers is figuring out how to either prevent errors from occurring or fixing them before they are used as part of a computation. On traditional computers, the problem is mostly solved by adding a parity bit—but that approach will not work with quantum computers because of the different nature of qubits—attempts to measure them destroy the data. Prior research has suggested that one possible solution to the problem is to group qubits into clusters called logical qubits. In this new effort, the team at AI Quantum has tested this idea on Google’s Sycamore quantum .

Sycamore works with 54 physical qubits, in their work, the researchers created logical qubits of different sizes ranging from five to 21 qubits to see how each would work. In so doing, they found that adding qubits reduced rates exponentially. They were able to measure the extra qubits in a way that did not involve collapsing their state, but that still provided enough information for them to be used for computations.

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Why can atoms or elementary particles behave like waves according to quantum physics, which allows them to be in several places at the same time? And why does everything we see around us obviously obey the laws of classical physics, where that is impossible? To answer those questions, in recent years researchers have coaxed larger and larger objects into behaving quantum mechanically. One consequence of this is that, when passing through a double slit, they form an interference pattern that is characteristic of waves.

Up to now this could be achieved with molecules consisting of a few thousand atoms. However, physicists hope one day to be able to observe such quantum effects with properly macroscopic objects. Lukas Novotny, Professor of Photonics, and his collaborators at the Department of Information Technology and Electrical Engineering at ETH Zurich have now made a crucial step in that direction. Their results were recently published in the scientific journal Nature.

Researchers at ETH Zurich have trapped a tiny sphere measuring a hundred nanometres using laser light and slowed down its motion to the lowest quantum mechanical state. Based on this, one can study quantum effects in macroscopic objects and build extremely sensitive sensors.

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Many of us swing through gates every day—points of entry and exit to a space like a garden, park or subway. Electronics have gates too. These control the flow of information from one place to another by means of an electrical signal. Unlike a garden gate, these gates require control of their opening and closing many times faster than the blink of an eye.

Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of Chicago’s Pritzker School of Molecular Engineering have devised a unique means of achieving effective gate operation with a form of processing called electromagnonics. Their pivotal discovery allows real-time control of information transfer between and magnons. And it could result in a new generation of classical electronic and quantum signal devices that can be used in various applications such as signal switching, low-power computing and quantum networking.

Microwave photons are forming the employed in, for example, wireless communications. Magnons are the particle-like representatives of “spin waves.” That is, wave-like disturbances in an ordered array of microscopically aligned spins that occur in certain magnetic materials.

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Researchers have found evidence for an anomalous phase of matter that was predicted to exist in the 1960s. Harnessing its properties could pave the way to new technologies able to share information without energy losses. These results are reported in the journal Science Advances.

While investigating a quantum material, the researchers from the University of Cambridge who led the study observed the presence of unexpectedly fast waves of energy rippling through the material when they exposed it to short and intense laser pulses. They were able to make these observations by using a microscopic speed camera that can track small and very fast movement on a scale that is challenging with many other techniques. This technique probes the material with two light pulses: the first one disturbs it and creates waves—or oscillations—propagating outward in concentric circles, in the same way as dropping a rock into a pond; the second light pulse takes a snapshot of these waves at various times. Put together, these images allowed them to look at how these waves behave, and to understand their ‘speed limit.’

“At , these waves move at a hundredth of the speed of light, much faster than we would expect in a normal material. But when we go to higher temperatures, it is as if the pond has frozen,” explained first author Hope Bretscher, who carried out this research at Cambridge’s Cavendish Laboratory. “We don’t see these waves moving away from the rock at all. We spent a long time searching for why such bizarre behavior could occur.”

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