Shot Noise of a Tunnel Junction Displacement Detector

TL;DR

This paper investigates how a nanomechanical oscillator coupled to a tunnel junction affects the quantum current noise, revealing significant signatures in shot noise that go beyond classical explanations, under various bias conditions.

Contribution

It provides a quantum-mechanical analysis of frequency-dependent shot noise in a tunnel junction coupled to a nanomechanical oscillator, including effects of bias and damping.

Findings

Large shot noise signatures due to oscillator dynamics.

Shot noise modifications cannot be explained classically.

Effects observed under both DC and AC bias conditions.

Abstract

We study quantum-mechanically the frequency-dependent current noise of a tunnel-junction coupled to a nanomechanical oscillator. The cases of both DC and AC voltage bias are considered, as are the effects of intrinsic oscillator damping. The dynamics of the oscillator can lead to large signatures in the shot noise, even if the oscillator-tunnel junction coupling is too weak to yield an appreciable signature in the average current. Moreover, the modification of the shot noise by the oscillator cannot be fully explained by a simple classical picture of a fluctuating conductance.