Dynamics of tunneling into nonequilibrium edge states

TL;DR

This paper explores how time-dependent perturbations can induce topological edge states in a trivial insulator, proposing an experiment to detect these states via tunneling conductance measurements, and analyzing related models.

Contribution

It introduces a method to detect nonequilibrium topological edge states through tunneling conductance and studies related models demonstrating dynamic localization effects.

Findings

Nonquantized metallic conductance near edges indicates topological edge states.

Bulk remains gapped while edges show conductance signatures.

Dynamic localization suppresses certain transport channels in driven models.

Abstract

Time-dependent perturbations can drive a trivial two-dimensional band insulator into a quantum Hall-like phase, with protected nonequilibrium states bound to its edges. We propose an experiment to probe the existence of these topological edge states which consists of passing a tunneling current through a small two-dimensional sample out of equilibrium. The signature is a nonquantized metallic conductance near the edges of the sample and, in contrast, an excitation gap in the bulk. This proposal is demonstrated for the case of a two-dimensional lattice model of Dirac electrons with tunable mass in a strong electromagnetic field. In addition, we also study the tunneling conductance of the driven resonant level model and find a phenomenon similar to dynamic localization in which certain transport channels are suppressed.