Universal equation of state and pseudogap in the two-dimensional Fermi gas

Abstract

We determine the thermodynamic properties and the spectral function for a homogeneous two-dimensional Fermi gas in the normal state using the Luttinger-Ward, or self-consistent T-matrix, approach. The density equation of state deviates strongly from that of the ideal Fermi gas even for moderate interactions, and our calculations suggest that temperature has a pronounced effect on the pressure in the crossover from weak to strong coupling, consistent with recent experiments. We also compute the superfluid transition temperature for a finite system in the crossover region. There is a pronounced pseudogap regime above the transition temperature: the spectral function shows a Bogoliubov-like dispersion with back-bending, and the density of states is significantly suppressed near the chemical potential. The contact density at low temperatures increases with interaction and compares well with both experiment and zero-temperature Monte Carlo results.

5+1 pages, 5 figures; v2: new pressure data at finite temperature

References in corpus (10)

• Many-Body Physics with Ultracold Gases
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Thermodynamics of the BCS-BEC crossover
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Exact Relations for a Strongly-interacting Fermi Gas from the Operator Product Expansion
• Viscosity and scale invariance in the unitary Fermi gas
• Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas
• Quantum mechanical limitations to spin diffusion in the unitary Fermi gas
• Short-range correlations and entropy in ultracold atomic Fermi gases
• A two-dimensional Fermi liquid with attractive interactions

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• Lattice Boltzmann simulations of a two-dimensional Fermi gas at unitarity
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