Strong Fulde-Ferrell Larkin-Ovchinnikov pairing fluctuations in polarized Fermi systems

TL;DR

This paper investigates FFLO pairing fluctuations in a polarized Fermi gas, revealing a strong enhancement near unitarity that could be experimentally observed as a peak in pair-momentum distribution.

Contribution

It demonstrates the presence of significant FFLO pairing fluctuations in polarized Fermi systems near unitarity using a self-consistent t-matrix approach.

Findings

Strong FFLO pairing fluctuations near unitarity.

Pronounced peak in pair-momentum distribution at finite momentum.

Potential for experimental detection in trapped gases.

Abstract

We calculate the pair susceptibility of an attractive spin-polarized Fermi gas in the normal phase, as a function of the pair momentum. Close to unitarity, we find a strong enhancement of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing fluctuations over an extended region of the temperature-polarization phase diagram, which manifests itself as a pronounced peak in the pair-momentum distribution at a finite pair momentum. This peak should be amenable to experimental observation at achievable temperatures in a box-like trapping potential, as a fingerprint of FFLO pairing. Our calculations rest on a self-consistent t-matrix approach which, for the unitary balanced Fermi gas, has been validated against experimental data for several thermodynamic quantities.