Noise properties of two single electron transistors coupled by a nanomechanical resonator

TL;DR

This paper investigates the noise characteristics of two single electron transistors coupled via a nanomechanical resonator, revealing how their interactions influence current correlations and noise enhancements.

Contribution

It introduces a classical model analyzing how a nanomechanical resonator mediates correlations and noise in coupled SETs, highlighting the role of back-action effects.

Findings

Coupled SETs act as independent heat baths for the resonator.

Positive current correlations are generated by the resonator coupling.

Low frequency noise can be significantly enhanced due to back-action.

Abstract

We analyze the noise properties of two single electron transistors (SETs) coupled via a shared voltage gate consisting of a nanomechanical resonator. Working in the regime where the resonator can be treated as a classical system, we find that the SETs act on the resonator like two independent heat baths. The coupling to the resonator generates positive correlations in the currents flowing through each of the SETs as well as between the two currents. In the regime where the dynamics of the resonator is dominated by the back-action of the SETs, these positive correlations can lead to parametrically large enhancements of the low frequency current noise. These noise properties can be understood in terms of the effects on the SET currents of fluctuations in the state of a resonator in thermal equilibrium which persist for times of order the resonator damping time.