Controlled dephasing of an electron interferometer with a path detector at equilibrium

TL;DR

This paper demonstrates that a nearly isolated electron puddle at thermal equilibrium can induce controlled dephasing in a nearby electron interferometer, revealing new insights into electron coherence and the Friedel Sum Rule.

Contribution

It introduces a novel mechanism of dephasing caused by an equilibrium electron puddle, expanding understanding of decoherence without external noise sources.

Findings

Complete dephasing occurs at certain electron occupations.

The phenomenon is explained by the Friedel Sum Rule.

The interferometer probes the physics of the isolated puddle.

Abstract

Controlled dephasing of electrons, via 'which path' detection, involves, in general, coupling a coherent system to a current driven noise source. However, here, we present a case in which a nearly isolated electron puddle at thermal equilibrium strongly affects the coherence of a nearby electronic interferometer. Moreover, for certain average electron occupations of the puddle, the interferometer exhibits complete dephasing. This robust phenomenon stems from the Friedel Sum Rule, which relates a system's occupation with its scattering phases. The interferometer opens a peeping window into physics of the isolated electron puddle, which cannot be accessed otherwise.