Signature of interaction in dc transport of ac gated Quantum Spin Hall edge states

TL;DR

This paper investigates how ac gate voltages influence electron transport in Quantum Spin Hall edge states, revealing unique forward scattering effects and signatures of electronic interactions in the dc tunneling current.

Contribution

It demonstrates the presence of a forward scattering spin channel in helical edge states and how ac gating can manipulate electron spin and reveal interaction signatures.

Findings

Ac gating induces a cusp pattern in the dc tunneling current.

Forward scattering spin channel is unique to Quantum Spin Hall edge states.

Electronic interactions produce observable signatures in transport measurements.

Abstract

In the presence of a scattering potential, electron transport in a quantum wire is known to be dramatically modified by backward scattering and unaffected by forward scattering processes. We show that the scenario is quite different in Quantum Spin Hall effect edge states coupled at a constriction. The helical nature of these states leads to the appearance of a forward scattering spin channel that is absent in other Luttinger liquid realizations. Suitably applied ac gate voltages can thus operate on the spin of electrons tunneling across the constriction, and induce in the dc tunneling current a cusp pattern that represents the signature of the edge state electronic interaction.