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.


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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
==========================================================================

Link to news story:
https://www.sciencedaily.com/releases/2023/05/230524181906.htm

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