Suppression of dephasing and phase lapses in the fractional quantum Hall regime

TL;DR

This paper investigates how a quantum dot acting as a charge fluctuator affects quantum transport in a fractional quantum Hall system, revealing unique phase lapses and visibility suppression without full dephasing.

Contribution

It demonstrates the distinct effects of fractional charge support on phase lapses and dephasing, expanding understanding of quantum transport in fractional quantum Hall regimes.

Findings

Abrupt phase lapses occur in fractional regimes.

Visibility is suppressed without complete dephasing.

Entanglement explains the observed phenomena.

Abstract

A charge fluctuator which is electrostatically coupled to a conducting channel may fully dephase quantum transport through the latter. Here, we address the case where a quantum dot (QD), playing the role of a charge fluctuator, is tunnel-coupled to an additional channel. In the case where the latter may support fractional charge, distinct differences from the integer case arise: Abrupt phase lapses of the transmission through the conducting channel occur (which may or may not be equal to $\pi$). This is accompanied by a cusp-like suppression of the interferometer's visibility, yet no full dephasing. We interpret our findings in terms of the entanglement between the fluctuator and the conducting channels.