BCS-BEC crossover of atomic Fermi superfluid in a spherical bubble trap

Abstract

We present a theory of a two-component atomic Fermi gas with tunable attractive contact interactions on a spherical shell going through the Bardeen-Cooper-Schrieffer (BCS) - Bose Einstein condensation (BEC) crossover, inspired by the realizations of spherical bubble traps for ultracold atoms in microgravity. The derivation follows the BCS-Leggett theory to obtain the gap and number equations. The BCS-BEC crossover can be induced by tuning the interaction, and the properly normalized gap and chemical potential exhibit universal behavior regardless of the planar or spherical geometry. Nevertheless, the spherical-shell geometry introduces another way of inducing the crossover by the curvature. The curvature-induced BCS-BEC crossover is made possible by fixing the particle number and interaction strength while shrinking the sphere, causing a reduction to the ratio of the pairing and kinetic energies and pushing the system towards the BCS limit. The saturation of the superfluid density further confirms the ground state is a Fermi superfluid.

10 pages, 6 figures, submitted

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Cited by in corpus (11)

• Low-dimensional quantum gases in curved geometries
• Shell-shaped atomic gases
• Scattering theory and equation of state of a spherical two-dimensional Bose gas
• Vortex structure and spectrum of atomic Fermi superfluid in a spherical bubble trap
• Faraday waves on a bubble Bose-Einstein condensed binary mixture
• Bose-Einstein condensation on axially-symmetric surfaces
• Two-component repulsive atomic Fermi gases in a thin spherical shell
• Dimer problem on a spherical surface
• Synthetic half-integer magnetic monopole and single-vortex dynamics in spherical Bose-Einstein condensates
• Two-component atomic Fermi superfluid with spin-orbital coupling in thin spherical-shell geometry
• Repulsive fermions and shell effects on the surface of a sphere