Optical properties of helical edge channels in zinc-blende-type topological insulators: Selection rules, circular and linear dichroism, circular and linear photocurrents

TL;DR

This paper develops a theoretical framework for understanding optical interactions with helical edge channels in zinc-blende topological insulators, revealing how symmetry-breaking enables unique optical transitions and photocurrent generation.

Contribution

It introduces a new theory describing electron-photon interactions in edge states, highlighting the role of symmetry and polarization in optical responses.

Findings

Electro-dipole optical transitions occur between spin branches due to lack of inversion symmetry.

Linear and circular dichroism are demonstrated in edge states.

Edge photocurrents can be controlled by radiation polarization.

Abstract

We develop a theory of electron-photon interaction for helical edge channels in two-dimensional topological insulators based on zinc-blende-type quantum wells. It is shown that the lack of space inversion symmetry in such structures enables the electro-dipole optical transitions between the spin branches of the topological edge states. Further, we demonstrate the linear and circular dichroism associated with the edge states and the generation of edge photocurrents controlled by radiation polarization.