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Category: quantum physics – Page 384

Quantum computing systems have the potential to outperform classical computers on some tasks, helping to solve complex real-world problems in shorter times. Research teams worldwide have thus been trying to realize this quantum advantage over traditional computers, by creating and testing different quantum systems.

Researchers at Tsinghua University recently developed a new programmable quantum phononic processor with trapped ions. This processor, introduced in a paper in Nature Physics, could be easier to scale up in size than other previously proposed photonic quantum processors, which could ultimately enable better performances on complex problems.

“Originally, we were interested in the proposal of Scott Aaronson and others about Boson sampling, which might show the quantum advantages of simple linear optics and photons,” Kihwan Kim, one of the researchers who carried out the study, told Phys.org. “We were wondering if it is possible to realize it with the in a trapped ion system.”

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It’s a very modern conjurer’s trick: Create a SXSW talk out of thin air, with the help of generative AI. That’s what whurley did this year in Austin. It took nine weeks for whurley — a staple of the Austin tech scene — to create and prepare for a keynote at SXSW 2018, where he would debut Strangeworks, a quantum computing startup he co-founded and runs. Five years later, generative AI would complete the task in just a few hours.

And it was actually pretty good. The 45-minute speech was comprehensive, interesting and struck a whurley-like tone. There was one swear word (fuck) and a few jokes (including two lawyer ones) that the audience laughed at.

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For their new study, the researchers aimed to understand how quantum correlations inside a source material, be it a gas or a mineral, would impact the quantum properties of the light bursts coming out, if at all. “High harmonic generation is a very important area. And still, until recently, it was described by a classical picture of light,” Kaminer says.

In quantum mechanics, figuring out what’s going on with more than a few particles at the same time is notoriously difficult. Kaminer and Alexey Gorlach, a graduate student in his lab, used their COVID-imposed isolation to try to make progress on a fully quantum description of light emitted in high harmonics. “It’s really crazy; Alexey built a super complex mathematical description on a scale that we’ve never had before,” Kaminer says.

Next, to fully incorporate the quantum properties of the material used to generate this light, Kaminer and Gorlach teamed up with Andrea Pizzi, then a graduate student at the University of Cambridge and now a postdoctoral fellow at Harvard University.

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With each of these splittings, the universe completely remolded itself. New particles arose to replace ones that could exist only in extreme conditions previously. The fundamental quantum fields of space-time that dictate how particles and forces interact with each other reconfigured themselves. We do not know how smoothly or roughly these phase transitions took place, but it’s perfectly possible that with each splitting, the universe settled into multiple identities at once.

This fracturing isn’t as exotic as it sounds. It happens with all kinds of phase transitions, like water turning into ice. Different patches of water can form ice molecules with different orientations. No matter what, all the water turns into ice, but different domains can have differing molecular arrangements. Where those domains meet walls, or imperfections, fracturing will appear.

Physicists are especially interested in the so-called GUT phase transition of our universe. GUT is short for “grand unified theory,” a hypothetical model of physics that merges the strong nuclear force with electromagnetism and the weak nuclear force. These theories are just beyond the reach of current experiments, so physicists and astronomers turn to the conditions of the early universe to study this important transition.

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Strongly correlated systems are systems made of particles that strongly interact with one another, to such an extent that their individual behavior depends on the behavior of all other particles in the system. In states that are far from equilibrium, these systems can sometimes give rise to fascinating and unexpected physical phenomena, such as many-body localization.

Many-body localization occurs when a system made of interacting particles fails to reach even at high temperatures. In many-body localized systems, particles thus remain in a state of non-equilibrium for long periods of time, even when a lot of energy is flowing through them.

Theoretical predictions suggest that the instability of the many-body localized phase is caused by small thermal inclusions in the strongly interacting system that act as a bath. These inclusions prompt the delocalization of the entire system, through a mechanism that is known as avalanche propagation.

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Most people only encounter turbulence as an unpleasant feature of air travel, but it’s also a notoriously complex problem for physicists and engineers. The same forces that rattle planes are swirling in a glass of water and even in the whorl of subatomic particles. Because turbulence involves interactions across a range of distances and timescales, the process is too complicated to be solved through calculation or computational modeling—there’s simply too much information involved.

Scientists have attempted to tackle the issue by studying the that occurs in superfluids, which is formed by tiny identical whirls called quantized vortices. A key question is how turbulence happens on the and how is it linked to turbulence at larger scales.

Researchers at Aalto University have brought that goal closer with a new study of quantum wave turbulence. Their findings, published in Nature Physics, demonstrate a new understanding of how wave-like motion transfers from macroscopic to microscopic length scales, and their results confirm a theoretical prediction about how the energy is dissipated at small scales.

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Physicists were surprised by the 2022 discovery that electrons in magnetic iron-germanium crystals could spontaneously and collectively organize their charges into a pattern featuring a standing wave. Magnetism also arises from the collective self-organization of electron spins into ordered patterns, and those patterns rarely coexist with the patterns that produce the standing wave of electrons physicists call a charge density wave.

In a study published this week in Nature Physics, Rice University physicists Ming Yi and Pengcheng Dai, and many of their collaborators from the 2022 study, present an array of experimental evidence that shows their charge density wave discovery was rarer still, a case where the magnetic and electronic orders don’t simply coexist but are directly linked.

“We found magnetism subtly modifies the landscape of electron energy states in the material in a way that both promotes and prepares for the formation of the charge density wave,” said Yi, a co-corresponding author of the study.

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A quantum device fabricated by Zhejiang University researchers could help to advance the design of quantum computers as it offers topological control over the units that store information within them. The team’s results were published in Science in December 2022.

Since their discovery around 2007, , known as , have been generating a lot of excitement due to their intriguing properties. For example, they are insulating in their interior, but conducting on their surfaces. This property stems from the topological nature of these materials, which makes them robust to deformations, so electrons moving along their surfaces resist any obstacles that might obstruct their flow.

Researchers have started to explore similar topological systems that are based on light rather than electrons—a field known as topological photonics. But so far, most such light-based systems have used classical forms of light rather than quantum ones. The ability to use quantum forms of light would open up many more possibilities and offer an opportunity to explore the quantum topology of light.

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