Steady states and edge state transport in topological Floquet-Bloch systems

TL;DR

This paper investigates the steady states and edge transport in two-dimensional Floquet topological insulators, revealing persistent topological signatures in non-equilibrium conditions through detailed modeling of bulk and edge state distributions.

Contribution

It provides a comprehensive analysis of open system dynamics and steady states in Floquet topological insulators, including effects of relaxation and coupling to leads, highlighting the persistence of topological features.

Findings

Steady states resemble topological insulators in the Floquet basis

Edge mode distributions show a Fermi-level-like feature

Topological signatures persist in non-equilibrium steady states

Abstract

We study the open system dynamics and steady states of two dimensional Floquet topological insulators: systems in which a topological Floquet-Bloch spectrum is induced by an external periodic drive. We solve for the bulk and edge state carrier distributions, taking into account energy and momentum relaxation through radiative recombination and electron-phonon interactions, as well as coupling to an external lead. We show that the resulting steady state resembles a topological insulator in the Floquet basis. The particle distribution in the Floquet edge modes exhibits a sharp feature akin to the Fermi level in equilibrium systems, while the bulk hosts a small density of excitations. We discuss two-terminal transport and describe the regimes where edge-state transport can be observed. Our results show that signatures of the non-trivial topology persist in the non-equilibrium steady state.