Suppression of stochastic fluctuations of suspended nanowires by temperature-induced single-electron tunnelling

TL;DR

This paper theoretically studies how temperature differences in a tunneling setup can suppress stochastic fluctuations in suspended nanowires, revealing a Gaussian stationary state with reduced mechanical noise.

Contribution

It introduces a quantum master equation approach to analyze electromechanical fluctuations under temperature gradients in nanowire systems.

Findings

Fluctuations are suppressed by temperature-induced single-electron tunneling.

The stationary state of the nanowire's motion is Gaussian.

Root-mean square fluctuations are smaller than at thermal equilibrium.

Abstract

We investigate theoretically the electromechanical properties of freely suspended nanowires that are in tunnelling contact with the tip of a scanning tunnelling microscope (STM) and two supporting metallic leads. The aim of our analysis is to characterize the fluctuations of the dynamical variables of the nanowire when a temperature drop is mantained between the STM tip and the leads, which are all assumed to be electrically grounded. By solving a quantum master equation that describes the coupled dynamics of electronic and mechanical degrees of freedom we find that the stationary state of the mechanical oscillator has a Gaussian character, but that the amplitude of its root-mean square center-of-mass fluctuations is smaller than would be expected if the system were coupled only to the leads at thermal equilibrium.