BCS-BEC crossover in a quasi-two-dimensional Fermi gas

Abstract

We consider a two-component gas of fermionic atoms confined to a quasi-two-dimensional (quasi-2D) geometry by a harmonic trapping potential in the transverse direction. We construct a mean field theory of the BCS-BEC crossover at zero temperature that allows us to extrapolate to an infinite number of transverse harmonic oscillator levels. In the extreme BEC limit, where the confinement length exceeds the dimer size, we recover 3D dimers confined to 2D with weak repulsive interactions. However, even when the interactions are weak and the Fermi energy is less than the confinement frequency, we find that the higher transverse levels can substantially modify fermion pairing. We argue that recent experiments on pairing in quasi-2D Fermi gases [Y. Zhang et al., Phys. Rev. Lett. 108, 235302 (2012)] have already observed the effects of higher transverse levels.

6 pages, 5 figures

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• Anomalous conductances in an ultracold quantum wire
• Criteria for 2D kinematics in an interacting Fermi gas
• Fermi Gases in the Two-Dimensional to Quasi-Two-Dimensional Crossover
• Breakdown of scale invariance in a quasi-two-dimensional Bose gas due to the presence of the third dimension
• Quasi-two-dimensional Fermi gases at finite temperature
• Chiral twodimensional p-wave superfluid from s-wave pairing in the BEC regime
• BCS-BEC Crossover in the Two-Dimensional Attractive Hubbard Model: Variational Cluster Approach
• Pseudogap regime of a strongly interacting two-dimensional Fermi gas with and without confinement-induced effect range of interactions
• Phases of circle-compactified QCD with adjoint fermions at finite density
• Role of the confinement-induced effective range on the thermodynamics of a strongly correlated Fermi gas in two dimensions
• Dimensional crossover in ultracold Fermi gases from Functional Renormalisation
• Renormalization group approach to the normal phase of 2D Fermi gases