Comparison of strong-coupling theories for a two-dimensional Fermi gas

Abstract

Understanding the formation of Cooper pairs and the resulting thermodynamic properties of a low-dimensional Fermi gas is an important area of research, elucidating our understanding of high temperature superconductors. In lower dimensions quantum fluctuations are expected to play an increasingly important role and the reliability of strong-coupling theories becomes questionable. Here, we present a comparison of recent thermodynamic measurements and theoretical predictions from different many-body $T$-matrix theories for a two-dimensional strongly interacting Fermi gas in the normal state. We find that the fully self-consistent $T$-matrix theory provides the best description of the experimental data over a wide range of temperatures and interatomic interactions. Our comparison reveals the crucial role played by the interactions between Cooper pairs and suggests that the future development of a quantitative strong-coupling theory for two-dimensional Fermi superfluids must explicitly take into account the diagrams that are responsible for pair-pair interactions.

Five pages, four figures

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• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
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• Exact few-body results for strongly correlated quantum gases in two dimensions
• Matter wave Fourier optics with a strongly interacting two-dimensional Fermi gas
• Comparative study of strong coupling theories of a trapped Fermi gas at unitarity
• Pairing effects in the normal phase of a two-dimensional Fermi gas
• Pairing and radio-frequency spectroscopy in two-dimensional Fermi gases

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• Fermi Gases in the Two-Dimensional to Quasi-Two-Dimensional Crossover
• Ground state of the two-dimensional attractive Fermi gas: essential properties from few- to many-body
• Visualizing the BEC-BCS crossover in the two-dimensional Fermi gas: pairing gaps and dynamical response functions from ab initio computations
• Dynamical structure factors of a two-dimensional Fermi superfluid within random phase approximation
• Collective modes of a two-dimensional Fermi gas at finite temperature
• Precision Many-Body Study of the Berezinskii-Kosterlitz-Thouless Transition and Temperature-Dependent Properties in the Two-Dimensional Fermi Gas
• Dimensional crossover in a strongly interacting ultracold atomic Fermi gas
• Effective theory for ultracold strongly interacting fermionic atoms in two dimensions
• Universal Properties of Fermi Gases in One-dimension
• Evolution of Cooper pairs with zero-center-of-mass momentum and their first-order correlation function in a two-dimensional ultracold Fermi gas near the observed Berezinskii-Kosterlitz-Thouless transition
• Polariton-polariton interaction beyond the Born approximation: A toy model study
• Harmonically trapped fermions in two dimensions: ground-state energy and contact of SU(2) and SU(4) systems via nonuniform lattice Monte Carlo
• Pseudogap regime of a strongly interacting two-dimensional Fermi gas with and without confinement-induced effect range of interactions
• Fermions in Two Dimensions: Scattering and Many-Body Properties
• Beyond Gaussian pair fluctuation theory for strongly interacting Fermi gases
• Role of the confinement-induced effective range on the thermodynamics of a strongly correlated Fermi gas in two dimensions
• Goldstone and Higgs Hydrodynamics in the BCS-BEC Crossover
• Pseudogap regime of a two-dimensional uniform Fermi gas
• Pseudogap phenomena near the BKT transition of a two-dimensional ultracold Fermi gas in the crossover region
• Interplay of the pseudogap and the BCS gap for heteropairs in ${}^{40}$K-${}^6$Li mixture