Trapped imbalanced fermionic superfluids in one dimension: A variational approach

Abstract

We propose and analyze a variational wave function for a population-imbalanced one-dimensional Fermi gas that allows for Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) type pairing correlations among the two fermion species, while also accounting for the harmonic confining potential. In the strongly interacting regime, we find large spatial oscillations of the order parameter, indicative of an FFLO state. The obtained density profiles versus imbalance are consistent with recent experimental results as well as with theoretical calculations based on combining Bethe ansatz with the local density approximation. Although we find no signature of the FFLO state in the densities of the two fermion species, we show that the oscillations of the order parameter appear in density-density correlations, both in-situ and after free expansion. Furthermore, above a critical polarization, the value of which depends on the interaction, we find the unpaired Fermi-gas state to be energetically more favorable.

Nine pages, six figures. Submitted to Phys. Rev. A

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Cited by in corpus (3)

• Spin-imbalanced ultracold Fermi gases in a two-dimensional array of tubes
• Hartree-Fock-Bogoliubov theory of trapped one-dimensional imbalanced Fermi systems
• Composite Bosons Superposition Ansatz Approach to One-Dimensional Trapped Few-Fermion Systems