Persistent current noise and electron-electron interactions

Abstract

We analyze fluctuations of persistent current (PC) produced by a charged quantum particle moving in a ring and interacting with a dissipative environment formed by diffusive electron gas. We demonstrate that in the presence of interactions such PC fluctuations persist down to zero temperature. In the case of weak interactions and/or sufficiently small values of the ring radius R PC noise remains coherent and can be tuned by external magnetic flux Φx piercing the ring. In the opposite limit of strong interactions and/or large values of R fluctuations in the electronic bath strongly suppress quantum coherence of the particle down to T=0 and induce incoherent Φx-independent current noise in the ring, which persists even at Φx=0 when the average PC is absent. © 2011 American Physical Society.