Noise-induced phase transition in the electronic Mach-Zehnder interferometer

TL;DR

This paper investigates how current noise from a quantum point contact causes dephasing in an electronic Mach-Zehnder interferometer, revealing a noise-induced phase transition at a specific QPC transparency.

Contribution

It introduces a novel analysis linking noise cumulants to visibility decay and identifies a sharp transition at QPC transparency T=1/2.

Findings

Visibility exhibits a sharp change at T=1/2

High-order cumulants cancel dilution effects at large bias

Quantum fluctuations smear the transition near T=1/2

Abstract

We consider dephasing in the electronic Mach-Zehnder interferometer strongly coupled to current noise created by a voltage biased quantum point contact (QPC). We find the visibility of Aharonov-Bohm oscillations as a function voltage bias and express it via the cumulant generating function of noise. In the large-bias regime, high-order cumulants of current add up to cancel the dilution effect of a QPC. This leads to an abrupt change in the dependence of the visibility on voltage bias which occurs at the QPC's transparency T=1/2. Quantum fluctuations in the vicinity of this point smear out the sharp transition.