Fragility of non-local edge mode transport in the quantum spin Hall state

TL;DR

This paper investigates the robustness of non-local edge mode transport in quantum spin Hall systems, finding it more fragile to disorder and dephasing than previously believed, which impacts potential applications in low-power electronics.

Contribution

It provides a comparative analysis of local and non-local resistance measurements in quantum spin Hall setups under various perturbations, revealing the fragility of non-local transport.

Findings

Non-local resistance is more affected by disorder and dephasing than local resistance.

Non-local edge mode transport in quantum spin Hall states is less robust than in quantum Hall systems.

Implications for the use of topological insulators in low-power electronic applications.

Abstract

Non-local currents and voltages are better able at withstanding the deleterious effects of dephasing than local currents and voltages in nanoscale systems. This hypothesis is known to be true in quantum Hall set-ups. We test this hypothesis in a four terminal quantum spin Hall set up wherein we compare the local resistance measurement with the non-local one. In addition to inelastic scattering induced dephasing we also test resilience of the resistance measurements in the aforesaid set-ups to disorder and spin-flip scattering. We find the axiom that non-local resistance is less affected by the detrimental effects of disorder and dephasing to be in general untrue for quantum spin Hall case. This has important consequences since it has been widely communicated that non-local transport through edge channels in topological insulators will have potential applications in low power information processing.