Exotic Topological States with Raman-Induced Spin-Orbit Coupling

TL;DR

This paper proposes an experimental scheme to realize topological states, including Chern insulators and superfluids, in ultracold atomic gases with Raman-induced spin-orbit coupling, revealing new phases and edge state behaviors.

Contribution

It introduces a simple method to generate spin-orbit coupling and topological phases in ultracold gases, including novel superfluid states with unique edge properties.

Findings

Realization of gapped Chern insulators and gapless topological semimetals.

Prediction of a gapped topological Fulde-Ferrell superfluid with same-chirality edge states.

Demonstration of rich topological phases induced by s-wave interactions.

Abstract

We propose a simple experimental scheme to realize simultaneously the one-dimensional spin-orbit coupling and the staggered spin-flip in ultracold pseudospin-$1/2$ atomic Fermi gases trapped in square optical lattices. In the absence of interspecies interactions, the system supports gapped Chern insulators and gapless topological semimetal states. By turning on the $s$-wave interactions, a rich variety of gapped and gapless inhomogeneous topological superfluids can emerge. In particular, a gapped topological Fulde-Ferrell superfluid, in which the chiral edge states at opposite boundaries possess the same chirality, is predicted.