Probing (topological) Floquet states through DC transport

TL;DR

This paper investigates how differential conductance measurements in periodically driven systems connected to electrodes can reveal topological Floquet states and their quasi-energy gaps, providing a practical method to detect topological edge states.

Contribution

It establishes a theoretical and numerical framework linking differential conductance to the quasi-energy spectrum of Floquet systems, highlighting its use as a topological probe.

Findings

Differential conductance quantization indicates topological edge states.

Conductance spectra accurately reflect quasi-energy gaps.

Analysis applies to both two and three terminal geometries.

Abstract

We consider the differential conductance of a periodically driven system connected to infinite electrodes. We focus on the situation where the dissipation occurs predominantly in these electrodes. Using analytical arguments and a detailed numerical study we relate the differential conductances of such a system in two and three terminal geometries to the spectrum of quasi-energies of the Floquet operator. Moreover these differential conductances are found to provide an accurate probe of the existence of gaps in this quasi-energy spectrum, being quantized when topological edge states occur within these gaps. Our analysis opens the perspective to describe the intermediate time dynamics of driven mesoscopic conductors as topological Floquet filters.