Pairing correlations in a trapped one-dimensional Fermi gas

Abstract

We use a BCS-type variational wavefunction to study attractively-interacting quasi one-dimensional (1D) fermionic atomic gases, motivated by cold-atom experiments that access the 1D regime using an anisotropic harmonic trapping potential (with trapping frequencies $ω_x = ω_y \gg ω_z$) that confines the gas to a cigar-shaped geometry. To handle the presence of the trap along the $z$-direction, we construct our variational wavefunction from the harmonic oscillator Hermite functions that are the eigenstates of the single-particle problem. Using an analytic determination of the effective interaction among harmonic oscillator states along with a numerical solution of the resulting variational equations, we make specific experimental predictions for how pairing correlations would be revealed in experimental probes like the local density and the momentum correlation function.