Nonequilibrium phonon backaction on the current noise in atomic-sized junctions

TL;DR

This paper investigates how phonon heating caused by tunneling electrons influences current noise in atomic junctions, revealing a significant backaction effect that becomes prominent at high voltages and low phonon damping.

Contribution

The authors develop a generalized kinetic approximation using extended Keldysh Green's functions to analyze phonon backaction effects on current noise.

Findings

Backaction contribution to noise exists at low phonon damping.

Significant noise correction occurs above phonon emission threshold.

Large voltage enhances phonon occupation fluctuations affecting noise.

Abstract

We study backaction effects of phonon heating due to tunneling electrons on the current noise in atomic-sized junctions. Deriving a generalized kinetic approximation within the extended Keldysh Green's functions technique, we demonstrate the existence of a characteristic backaction contribution to the noise in case of low external phonon damping. We provide a physically intuitive interpretation of this contribution at large voltage in terms of slow fluctuations of the phonon occupation, and show that it generally gives a significant correction to the noise above the phonon emission threshold.