Non-Equilibrium Transport Through a Gate-Controlled Barrier on the Quantum Spin Hall Edge

TL;DR

This paper investigates non-equilibrium transport in quantum spin Hall edge states with a gate-controlled impurity, providing a theoretical framework to interpret conductance measurements and infer interaction strengths.

Contribution

It introduces a tunable impurity model on quantum spin Hall edges and computes conductance for various conditions using integrability, including effects of leads and interactions.

Findings

Conductance depends on interactions, temperature, and voltage.

The model allows extraction of interaction strength from transport data.

The approach is applicable to experimental setups with gate-controlled barriers.

Abstract

The Quantum Spin Hall insulator is characterized by the presence of gapless helical edge states where the spin of the charge carriers is locked to their direction of motion. In order to probe the properties of the edge modes, we propose a design of a tunable quantum impurity realized by a local gate under an external magnetic field. Using the integrability of the impurity model, the conductance is computed for arbitrary interactions, temperatures and voltages, including the effect of Fermi liquid leads. The result can be used to infer the strength of interactions from transport experiments