Persistent current noise

TL;DR

This paper investigates the quantum fluctuations of persistent current in meso- and nanorings, revealing conditions under which current noise persists at zero temperature and how it can be controlled via magnetic flux.

Contribution

It provides an explicit evaluation of persistent current noise power in a quantum ring model, highlighting the role of non-commuting current operators and quantum coherence effects.

Findings

Persistent current noise can exist at zero temperature if the current operator does not commute with the Hamiltonian.

Noise power exhibits sharp peaks that broaden with multiple channels or dissipation.

External magnetic flux can tune the persistent current noise, demonstrating quantum coherence effects.

Abstract

We demonstrate that persistent current in meso- and nanorings may fluctuate down to zero temperature provided the current operator does not commute with the total Hamiltonian of the system. For a model of a quantum particle on a ring we explicitly evaluate PC noise power which has a form of sharp peaks which become broadened for multi-channel rings or in the presence of dissipation. PC noise can be tuned by an external magnetic flux which is a fundamental manifestation of quantum coherence in the system.