Superradiance induced particle flow via dynamical gauge coupling

TL;DR

This paper investigates how superradiance in a cavity-coupled fermionic lattice induces directed particle flow, analyzing both infinite and finite systems with boundary effects and fluctuations.

Contribution

It introduces a model of fermions with dynamical gauge coupling in a lattice, revealing superradiant phases and non-unique steady states influenced by cavity fluctuations.

Findings

Superradiant phase with infinitesimal threshold induces directed flow.

Finite lattice steady states are non-unique and influenced by fluctuations.

Long-term dynamics are governed by cavity fluctuations and coherent excitations.

Abstract

We study fermions that are gauge-coupled to a cavity mode via Raman-assisted hopping in a one dimensional lattice. For an infinite lattice, we find a superradiant phase with infinitesimal pumping threshold which induces a directed particle flow. We explore the fate of this flow in a finite lattice with boundaries, studying the non-equilibrium dynamics including fluctuation effects. The short time dynamics is dominated by superradiance, while the long time behaviour is governed by cavity fluctuations. We show that the steady state in the finite lattice is not unique, and can be understood in terms of coherent bosonic excitations above a Fermi surface in real space.