MSGID: 1:317/3 646ee468   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Quantum matter breakthrough: Tuning density waves    
      
     Date:   
         May 24, 2023   
     Source:   
         Ecole Polytechnique Fe'de'rale de Lausanne   
     Summary:   
         Scientists have found a new way to create a crystalline structure   
         called a 'density wave' in an atomic gas. The findings can help   
         us better understand the behavior of quantum matter, one of the   
         most complex problems in physics.   
      
      
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   FULL STORY   
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   Scientists at EPFL have found a new way to create a crystalline   
   structure called a "density wave" in an atomic gas. The findings can   
   help us better understand the behavior of quantum matter, one of the   
   most complex problems in physics.   
      
   "Cold atomic gases were well known in the past for the ability to   
   'program' the interactions between atoms," says Professor Jean-Philippe   
   Brantut at EPFL. "Our experiment doubles this ability!" Working with   
   the group of Professor Helmut Ritsch at the University of Innsbruck,   
   they have made a breakthrough that can impact not only quantum research   
   but quantum-based technologies in the future.   
      
   Density waves Scientists have long been interested in understanding how   
   materials self- organize into complex structures, such as crystals. In the   
   often-arcane world of quantum physics, this sort of self-organization of   
   particles is seen in 'density waves', where particles arrange themselves   
   into a regular, repeating pattern or 'order'; like a group of people   
   with different colored shirts on standing in a line but in a pattern   
   where no two people with the same color shirt stand next to each other.   
      
   Density waves are observed in a variety of materials, including metals,   
   insulators, and superconductors. However, studying them has been   
   difficult, especially when this order (the patterns of particles in the   
   wave) occurs with other types of organization such as superfluidity --   
   a property that allows particles to flow without resistance.   
      
   It's worth noting that superfluidity is not just a theoretical curiosity;   
   it is of immense interest for developing materials with unique properties,   
   such as high-temperature superconductivity, which could lead to more   
   efficient energy transfer and storage, or for building quantum computers.   
      
   Tuning a Fermi gas with light To explore this interplay, Brantut and   
   his colleagues, the researchers created a "unitary Fermi gas," a thin   
   gas of lithium atoms cooled to extremely low temperatures, and where   
   atoms collide with each other very often.   
      
   The researchers then placed this gas in an optical cavity, a device used   
   to confine light in a small space for an extended period of time. Optical   
   cavities are made of two facing mirrors that reflect incoming light back   
   and forth between them thousands of times, allowing light particles,   
   photons, to build up inside the cavity.   
      
   In the study, the researchers used the cavity to cause the particles in   
   the Fermi gas to interact at long distance: a first atom would emit a   
   photon that bounces onto the mirrors, which is then reabsorbed by second   
   atom of the gas, regardless how far it is from the first. When enough   
   photons are emitted and reabsorbed -- easily tuned in the experiment --   
   the atoms collectively organize into a density wave pattern.   
      
   "The combination of atoms colliding directly with each other in the Fermi   
   gas, while simultaneously exchanging photons over long distance, is a new   
   type of matter where the interactions are extreme," says Brantut. "We   
   hope what we will see there will improve our understanding of some of   
   the most complex materials encountered in physics."   
       * RELATED_TOPICS   
             o Matter_&_Energy   
                   # Physics # Quantum_Physics # Optics # Chemistry   
             o Computers_&_Math   
                   # Quantum_Computers # Spintronics_Research #   
                   Computers_and_Internet # Encryption   
       * RELATED_TERMS   
             o Particle_physics o Quantum_mechanics o Electron_configuration   
             o Wave-particle_duality o Introduction_to_quantum_mechanics   
             o Quantum_tunnelling o Physics o Breaking_wave   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Ecole_Polytechnique_Fe'de'rale_de_Lausanne. Original written by Nik   
   Papageorgiou. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Victor Helson, Timo Zwettler, Farokh Mivehvar, Elvia Colella,   
      Kevin Roux,   
         Hideki Konishi, Helmut Ritsch, Jean-Philippe Brantut. Density-wave   
         ordering in a unitary Fermi gas with photon-mediated interactions.   
      
         Nature, 2023; DOI: 10.1038/s41586-023-06018-3   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230524181906.htm   
      
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