Z2 peak of noise correlations in a quantum spin Hall insulator

TL;DR

This paper studies the behavior of noise correlations in a quantum spin Hall insulator, revealing a robust Z2 peak related to time reversal symmetry and helical edge states under a magnetic field.

Contribution

It uncovers a novel Z2 peak in noise correlations caused by the interplay of magnetic field, disorder, and helical edge states in quantum spin Hall insulators.

Findings

Noise correlations vanish at zero magnetic field.

Noise correlations become negative when magnetic field is applied.

The Z2 peak is linked to time reversal symmetry and helical edge states.

Abstract

We investigate the current noise correlations at a quantum point contact in a quantum spin Hall structure, focusing on the effect of a weak magnetic field in the presence of disorder. For the case of two equally biased terminals we discover a robust peak: the noise correlations vanish at $B = 0 $ and are negative for $B\not = 0 $. We find that the character of this peak is intimately related to the interplay between time reversal symmetry and the helical nature of the edge states and call it the Z2 peak.