Photon-Inhibited Topological Transport in Quantum Well Heterostructures

Abstract

Here we provide a picture of transport in quantum well heterostructures with a periodic driving field in terms of a probabilistic occupation of the topologically protected edge states in the system. This is done by generalizing methods from the field of photon assisted tunneling. We show that the time dependent field dresses the underlying Hamiltonian of the heterostructure and splits the system into side-bands. Each of these sidebands is occupied with a certain probability which depends on the drive frequency and strength. This leads to a reduction in the topological transport signatures of the system because of the probability to absorb/emit a photon. Therefore when the voltage is tuned to the bulk gap the conductance is smaller then the expected 2e 2 /h. We refer to this as photon inhibited topological transport. Nevertheless, the edge modes reveal their topological origin in the robustness of the edge conductance to disorder and changes in model parameters. In this work the analogy with photon assisted tunneling allows us to interpret the calculated conductivity and explain the sum rule observed by previous authors [1] Introduction.-Topological states of matter are currently at the forefront of research in condensed matter physics. From the quantum hall effect to topological superconductors, these states are of interest for a variety of reasons. In topological insulators the in-gap edge states are of primary interest. These states are topologically protected, meaning they are insensitive to deformations of the Hamiltonian's parameters that leave the topological gap intact and the effects of disorder. The existence of such states provides a physical signature of the topology in the charge and spin conductance.

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Floquet topological phases coupled to environments and the induced photocurrent

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Floquet Majorana zero and π modes in planar Josephson junctions

“…To probe these transport quantities, we use the Floquet-Landauer formalism which has been utilized previously in related topological Floquet setups [30,[81][82][83][84][85]. We attach static leads to the 1D effective wire in the wide-band and weak-coupling limits.…”