Noise dephasing in the edge states of the Integer Quantum Hall regime

TL;DR

This paper investigates how electrical noise, both shot and thermal, causes dephasing in edge states of the Integer Quantum Hall regime, using an interferometer and a Gaussian noise theory to explain finite temperature coherence.

Contribution

It demonstrates that electrical noise induces dephasing in quantum Hall edge states and develops a Gaussian noise-based theory that aligns well with experimental observations.

Findings

Electrical shot noise causes phase randomization in edge states.

Thermal noise also contributes to dephasing, affecting coherence time.

The Gaussian noise model accurately predicts experimental results.

Abstract

An electronic Mach Zehnder interferometer is used in the integer quantum hall regime at filling factor 2, to study the dephasing of the interferences. This is found to be induced by the electrical noise existing in the edge states capacitively coupled to each others. Electrical shot noise created in one channel leads to phase randomization in the other, which destroys the interference pattern. These findings are extended to the dephasing induced by thermal noise instead of shot noise: it explains the underlying mechanism responsible for the finite temperature coherence time $\tau_\phi(T)$ of the edge states at filling factor 2, measured in a recent experiment. Finally, we present here a theory of the dephasing based on Gaussian noise, which is found in excellent agreement with our experimental results.