Noise and Bistabilities in Quantum Shuttles

TL;DR

This paper investigates current fluctuations in quantum shuttles, revealing that giant noise enhancements are due to bistable switching mechanisms, supported by numerical analysis of cumulants and noise spectra.

Contribution

It demonstrates that bistable switching causes giant noise in different quantum shuttle models, extending understanding of noise mechanisms in nanoscale systems.

Findings

Giant zero-frequency noise linked to bistable switching.

Similar noise enhancement mechanisms in different quantum shuttle models.

Numerical estimates of effective switching rates.

Abstract

We present a study of current fluctuations in two models proposed as quantum shuttles. Based on a numerical evaluation of the first three cumulants of the full counting statistics we have recently shown that a giant enhancement of the zero-frequency current noise in a single-dot quantum shuttle can be explained in terms of a bistable switching between two current channels. By applying the same method to a quantum shuttle consisting of a vibrating quantum dot array, we show that the same mechanism is responsible for a giant enhancement of the noise in this model, although arising from very different physics. The interpretation is further supported by a numerical evaluation of the finite-frequency noise. For both models we give numerical results for the effective switching rates.