Tunneling between helical edge states through extended contacts

TL;DR

This paper studies tunneling between helical edge states in a quantum spin Hall system with an extended contact, revealing how geometry influences backscattering and enabling confirmation of edge state properties.

Contribution

It introduces an analysis of extended contacts in quantum spin Hall systems, showing their effects on backscattering and methods to extract edge state velocities.

Findings

Extended contacts modify backscattering current behavior.

Power-law behaviors depend on energy scale.

Configuration helps confirm helical nature of edge states.

Abstract

We consider a quantum spin Hall system in a two-terminal setup, with an extended tunneling contact connecting upper and lower edges. We analyze the effects of this geometry on the backscattering current as a function of voltage, temperature, and strength of the electron interactions. We find that this configuration may be useful to confirm the helical nature of the edge states and to extract their propagation velocity. By comparing with the usual quantum point contact geometry, we observe that the power-law behaviors predicted for the backscattering current and the linear conductance are recovered for low enough energies, while different power-laws also emerge at higher energies.