Enhanced visibility of the Fulde-Ferrell-Larkin-Ovchinnikov state in one dimensional Bose-Fermi mixtures near the immiscibility point

TL;DR

This study numerically demonstrates that the visibility of the FFLO state in one-dimensional Bose-Fermi mixtures is significantly enhanced near the phase-separation point, with observable density oscillations indicating the modulated Fermi superfluid.

Contribution

It introduces a numerical analysis showing how bosons can be used to detect the FFLO state in cold atom experiments near phase separation.

Findings

Enhanced visibility of FFLO state near phase separation

Large amplitude oscillations in density profiles

Detectable static structure factors in experiments

Abstract

Based on the matrix product states method, we investigate numerically the ground state properties of one-dimensional mixtures of repulsive bosons and spin-imbalanced attractive fermions, the latter being in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, where Cooper pairs condense at a finite momentum $k=k_{FFLO}$. We find that the visibility of such a state is dramatically enhanced as the repulsive Bose-Fermi mixture is brought close to the phase-separation point. In particular, large amplitude self-induced oscillations with wave-vector $2k_{FFLO}$ appear in both the fermion total density and the boson density profiles, leaving sharp fingerprints in the corresponding static structure factors. We show that these features remain well visible in cold atoms systems trapped longitudinally by a smooth flat-bottom potential. Hence bosons can be used to directly reveal the modulated Fermi superfluid in experiments.