Phase diagram and topological superfluid state of spin-orbit coupled Fermi gas with attractive interactions in a one-dimensional optical lattice

TL;DR

This paper uses density matrix renormalization group methods to map out the phase diagram of a spin-orbit coupled Fermi gas in a one-dimensional optical lattice, revealing a topological superfluid state with potential for cold atom experiments.

Contribution

It provides the first comprehensive phase diagram including the topological superfluid state in a 1D spin-orbit coupled Fermi gas with attractive interactions.

Findings

Identification of exotic pairings induced by spin-orbit coupling

Demonstration of phase transitions between different pairing states

Confirmation of the topological superfluid state's existence in 1D systems

Abstract

Based on density matrix renormalization group method, we investigate the spin-orbit coupled Fermi gas with attractive interactions in one-dimensional optical lattice and present a complete phase diagram for a quarter-filling system with intermediate strong interactions. We unveil the exotic pairings induced by spin-orbit couplings and the phase transitions between different pairing states, and further demonstrate the existence of the long-sought topological superfluid state at moderate magnetic field and spin-orbit coupling strength. For the particle conserved system, this topological superfluid state can be fixed by its gapless single particle excitation, Luttinger parameter and non-trivial boundary effect. Our study removes out the widespread doubt on the existence of topological superfluid in one dimension and paves the way for simulating topological superfluid states in cold atom settings.