Dynamics of tunneling into nonequilibrium edge states

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