Energy filtered leads for quantized transport in Floquet systems*

In equilibrium, robust electronic edge or surface modes play key roles in the fascinating quantized responses exhibited by topological materials. Topological bands and edges states can be induced dynamically even in trivial materials, using a time-periodic drive. In contrast to their equilibrium counterparts, the dynamically induced Floquet topological insulators do not exhibit quantized transport when probed using conventional measurements, such as the differential conductance. This lack of quantization arises due to photon assisted tunneling from the system to the leads and vice versa. We show that quantization of the differential conductance can be restored by connecting the system and the leads via an energy filter. We discuss the utility of this approach for achieving quantization of other responses in topological Floquet systems.