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Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
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Observation of Coherent Multiorbital Polarons in a Two-Dimensional Fermi Gas
N Darkwah Oppong1,2, L Riegger1,2, O Bettermann1,2
1Ludwig-Maximilians-Universität, Schellingstraße 4, 80799 München, Germany.
Physical Review Letters
|May 31, 2019
Summary
Researchers observed multiorbital polarons in a 2D ultracold Fermi gas of Ytterbium atoms. They characterized these polarons, finding the repulsive polaron to be a long-lived quasiparticle, paving the way for new many-body physics studies.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Condensed Matter Physics
- Quantum Gases
Background:
- Ultracold Fermi gases provide a platform for studying quantum many-body phenomena.
- Polarons, quasiparticles formed by impurities interacting with a quantum medium, are crucial for understanding emergent properties.
- Multiorbital systems offer richer physics due to complex interactions and orbital degrees of freedom.
Purpose of the Study:
- To experimentally observe and characterize multiorbital polarons in a two-dimensional (2D) Fermi gas.
- To investigate the properties of attractive and repulsive polarons near an orbital Feshbach resonance.
- To develop a theoretical framework for understanding interorbital interactions in 2D Fermi gases.
Main Methods:
- Creation of a 2D Fermi gas using ^{173}Yb atoms with impurities in the metastable ^{3}P_{0} orbital and a Fermi sea in the ground-state ^{1}S_{0} orbital.
- Spectroscopic probing of polaron energies (attractive and repulsive).
- Measurement of quasiparticle residue to characterize polaron coherence.
- Formulation of a many-body theory to model interorbital interactions.
Main Results:
- Experimental observation of multiorbital polarons in the 2D Ytterbium Fermi gas.
- Spectroscopic determination of attractive and repulsive polaron energies near an orbital Feshbach resonance.
- Characterization of the repulsive polaron as a long-lived quasiparticle with a decay rate significantly below its energy.
- Development of a many-body theory that accurately describes interorbital interactions and matches experimental findings.
Conclusions:
- The study successfully observed and characterized multiorbital polarons in a 2D ultracold Fermi gas.
- The repulsive polaron exhibits long-lived quasiparticle behavior, offering a stable platform for further investigation.
- The developed many-body theory provides a robust tool for understanding such systems.
- This work opens new avenues for exploring many-body physics in multiorbital ultracold Fermi gases.
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