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A new way to create a crystalline structure called a “density wave”

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  A density wave (DW) is a fundamental type of long-range order in quantum matter tied to self-organization into a crystalline structure. Although density waves are seen in a wide range of materials, such as metals, insulators, and superconductors, studying them has proven challenging, particularly when this order (the patterns of the wave’s particles) coexists with other types of organization, such as superfluidity, which allows particles to flow without resistance. Scientists at EPFL have found a new way to create a “density wave” in an atomic gas. The findings could lead to a better understanding of the behavior of quantum matter. Professor Jean-Philippe Brantut at EPFL said, “Cold atomic gases were well known in the past for the ability to ‘program’ the interactions between atoms. Our experiment doubles this ability!” To study this interaction, Brantut, and his colleagues created a “unitary Fermi gas,” a thin gas of lithium atoms that has been cooled to incredibly low temperatures
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Tireless electrons in mesoscopic gold rings

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The surprising prediction that currents can flow forever in small normal metal rings was confirmed almost twenty years ago. Highly precise new experiments find good agreement with theory that was not seen till now. Figure 1: (Top) This is an artist’s concept, adapted from Ref. [15], showing part of the SQUID assembly—the field and pickup loops hovering over the gold rings of the sample. (Bottom) This figure (Fig. 3(a) from Ref. [9]) presents the difference between the averaged nonlinear responses, induced by the flux and measured by the SQUID, of two rings with sizeable responses, at a range of temperatures vs the applied external flux. Multiple data sets for some temperatures attest to the reproducibility of the results. An approximately fitted sinusoidal curve yields a period which is close to h/eℎ/� It is well known that in a superconductor electrons react strongly to a magnetic field, creating currents that try to shield the flux in the bulk case (the Meissner effect) or cause the
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Study demonstrates many-body chemical reactions in a quantum degenerate gas

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  In recent years, physicists have been trying to attain the control of chemical reactions in the quantum degenerate regime, where de Broglie wavelength of particles becomes comparable to the spacing between them. Theoretical predictions suggest that many-body reactions between bosonic reactants in this regime will be marked by quantum coherence and Bose enhancement, yet this has been difficult to validate experimentally. Researchers at University of Chicago recently set out to observe these elusive many-body chemical reactions in the quantum degenerate regime. Their paper, published in Nature Physics, presents the observation of coherent, collective reactions between Bose-condensed atoms and molecules. "The quantum control of molecular reactions is a fast-progressing research area in atomic and molecular physics," Cheng Chin, one of the researchers who carried out the study, told Phys.org. "People envision applications of cold molecules in precision metrology, quantum i
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Physicists Create New Exotic State of Matter: Bosonic Correlated Insulator

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  This is the first time a highly ordered crystal of bosonic particles called excitons has been created in a real — as opposed to synthetic — matter system. Subatomic particles come in one of two broad types: fermions and bosons. One of the biggest distinctions is in their behavior. Bosons can occupy the same energy level; fermions don’t like to stay together. Together, these behaviors construct the Universe as we know it.. Fermions, such as electrons, underlie the matter with which we are most familiar as they are stable and interact through the electrostatic force. Meanwhile bosons, such as photons, tend to be more difficult to create or manipulate as they are either fleeting or do not interact with each other. “A clue to their distinct behaviors is in their different quantum mechanical characteristics,” said first author Richen Xiong, a graduate student at the University of California at Santa Barbara. “Fermions have half-integer spins such as 1/2 or 3/2 etc., while bosons have whol
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Advancing neutron diffraction for accurate structural measurement of light elements at megabar pressures

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For decades, scientists sought a way to apply the outstanding analytical capabilities of neutrons to materials under pressures approaching those surrounding the Earth's core. These extreme pressures can rearrange a material's atoms, potentially resulting in interesting new properties Be an ACS Industry Insider Sign-up and get free, monthly access to articles that cover exciting, cutting edge discoveries in Energy, Environmental Science and Agriculture A breakthrough resulted in 2022 when researchers at Oak Ridge National Laboratory's Spallation Neutron Source squeezed a tiny sample of material—sandwiched between two diamonds—to a record 1.2 million times the average air pressure at sea level, or approximately 1.2 megabar. But this was only the start—they still had to produce useful data from the experiments. Now those same scientists have implemented software that removes the signal interference affecting the neutrons as they pass through the diamonds before reaching the sa
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Time Crystals: A New Form of Matter That Could Change Everything

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Of all the science-fiction-sounding names that have come to fruition in recent years, perhaps none is as mysterious or seemingly fictitious as time crystals. The name evokes something between Back to the Future and Donnie Darko, and the reality is perhaps crazier than either. Two separate groups of scientists recently reported they observed time crystals, which lends credence to the idea that this theoretical state of matter is something humans can actually create and observe. And indeed, time crystals can be grown in a child’s bedroom. But, it requires nuclear sensors and lasers to help time crystals reach their full potential and then measure and observe them. This combination of dramatic scientific terms and shockingly simple objects is a great analogy for time crystals as a whole. Read on to understand what they are and how they might affect our lives.   What Are Time Crystals? Time crystals are systems of atoms that arrange themselves in time the way more traditional solids crysta
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Paradoxical Crystal Baffles Physicists

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At super-low temperatures, a crystal called samarium hexaboride behaves in an unexplained, imagination-stretching way. Interactions between electrons inside samarium hexaboride appear to be giving rise to an exotic quantum behavior new to researchers. In a deceptively drab black crystal, physicists have stumbled upon a baffling behavior, one that appears to blur the line between the properties of metals, in which electrons flow freely, and those of insulators, in which electrons are effectively stuck in place. The crystal exhibits hallmarks of both simultaneously. “This is a big shock,” said Suchitra Sebastian, a condensed matter physicist at the University of Cambridge whose findings appeared today in an advance online edition of the journal Science. Insulators and metals are essentially opposites, she said. “But somehow, it’s a material that’s both. It’s contrary to everything that we know.” The material, a much-studied compound called samarium hexaboride or SmB6, is an insulator at
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