Cavity-induced generation of non-trivial topological states in a two-dimensional Fermi gas

TL;DR

This paper demonstrates how a two-dimensional Fermi gas coupled to an optical cavity can self-organize into topologically non-trivial states with protected edge modes, driven by cavity-induced gauge fields.

Contribution

It introduces a method for dynamically generating topological states in a fermionic gas via cavity-induced gauge fields and self-organization.

Findings

Fermions self-organize into topologically non-trivial states.

Cavity field induces a dynamical gauge field.

Topological states are protected by dissipation.

Abstract

We propose how topologically non-trivial states can dynamically organize in a fermionic quantum gas which is confined to a two-dimensional optical lattice potential and coupled to the field of an optical cavity. The spontaneously emerging cavity field induces together with coherent pump laser fields a dynamical gauge field for the atoms. Upon adiabatic elimination of the cavity degree of freedom, the system is described by an effective Hofstadter model with a self-consistency condition which determines the tunneling amplitude along the cavity direction. The fermions are found to self-organize into topologically non-trivial states which carry an extended edge state for a finite system size. Due to the dissipative nature of the cavity field, the topological steady states are protected from external perturbations.