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

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 boxlike 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.

Automated summary

In this study, the pair susceptibility of an attractive spin-polarized Fermi gas in the normal phase was calculated as a function of pair momentum. It was found that close to unitarity, there is a strong enhancement of FFLO pairing fluctuations, which could be observed experimentally as a pronounced peak in the pair-momentum distribution. The calculations were based on a self-consistent t-matrix approach and have been validated against experimental data for several thermodynamic quantities in the unitary balanced Fermi gas system.