Time-dependent transport in gated topological insulators

The surface states of topological insulators (TI) possess a linear dispersion in the low-energy approximation, and are protected against time-reversal-invariant perturbations such as non-magnetic impurities, defects. The chiral nature of TI surface states can induce perfect quantum tunneling for Dirac fermions incident in the normal direction, which can be utilized in some novel TI-based devices. Recently, the effect of the time-dependent perturbation has been paid much more attention, especially the optical response of the TI surface states. However, the modulation of the time-dependent potential on the transport properties has obtained much less attention. Here we apply the scattering matrix method based on the low-energy Hamiltonian to analyze the transport characteristic of a gated topological insulator in the presence of a time-dependent potential.