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Density-wave ordering in a unitary Fermi gas with photon-mediated interactions
Victor Helson1,2, Timo Zwettler1,2, Farokh Mivehvar3
1Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Nature
|May 24, 2023
Summary
Researchers created a tunable quantum gas with both contact and long-range interactions. They observed density wave order stabilized by long-range forces, offering a new platform for studying quantum matter.
Area of Science:
- Quantum Matter Physics
- Atomic, Molecular, and Optical Physics
Background:
- Density waves (DW) represent long-range order in quantum systems, crucial for understanding self-organization.
- The interplay between DW order and superfluidity presents significant theoretical challenges.
- Tunable quantum Fermi gases are vital for exploring strongly interacting fermion physics.
Purpose of the Study:
- To experimentally investigate the interplay of density wave order and superfluidity in a tunable quantum Fermi gas.
- To explore the influence of both contact and long-range interactions on density wave formation.
- To establish a controllable platform for studying quantum phenomena.
Main Methods:
- Realization of a Fermi gas with tunable contact and photon-mediated long-range interactions in an optical cavity.
- Utilizing a transversely driven high-finesse optical cavity to engineer interactions.
- Identifying density wave order through superradiant light-scattering properties.
- Quantitatively measuring the onset of DW order across the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover.
Main Results:
- Density wave order was stabilized above a critical long-range interaction strength.
- The onset of DW order was measured as contact interactions were tuned across the BCS-BEC crossover, showing qualitative agreement with mean-field theory.
- Atomic DW susceptibility was tuned over an order of magnitude by adjusting long-range interactions, demonstrating independent control.
Conclusions:
- The experimental system provides a fully tunable and microscopically controllable platform for studying the interplay of superfluidity and density wave order.
- The findings offer new insights into the complex phase diagrams of quantum matter.
- This work paves the way for future investigations into exotic quantum phases and phenomena.
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