Shot noise of a tunnel junction displacement detector

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.