Topological Fulde-Ferrel-Larkin-Ovchinnikov states in Spin-orbit Coupled Fermi Gases

TL;DR

This paper predicts and characterizes a topological FFLO superfluid state in a 2D spin-orbit coupled Fermi gas with Zeeman fields, highlighting its stability and experimental detectability.

Contribution

It introduces a novel topological FFLO state stabilized by spin-orbit coupling and Zeeman fields, with detailed phase diagram analysis and experimental signatures.

Findings

Topological FFLO state characterized by non-trivial Berry phase.

Stable in a specific region of the zero-temperature phase diagram.

Distinct signatures in quasi-particle spectra and momentum distribution.

Abstract

Pairing in an attractively interacting two-component Fermi gas in the absence of the inversion symmetry and/or the time-reversal symmetry may give rise to exotic superfluid states. Notable examples range from the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state with a finite center-of-mass momentum in a polarized Fermi gas, to the topological superfluid state in a two-dimensional Fermi gas under Rashba spin-orbit coupling and an out-of-plane Zeeman field. Here, we show that a topological FFLO state can be stabilized in a two-dimensional Fermi gas with Rashba spin-orbit coupling and both in-plane and out-of-plane Zeeman fields. We characterize the topological FFLO state by a non-trivial Berry phase, and demonstrate the stability region of the state on the zero-temperature phase diagram. Given its unique properties in both the quasi-particle dispersion spectra and the momentum distribution, signatures of the topological FFLO state can be detected using existing experimental techniques.