Anomalous suppression of the shot noise in a nanoelectromechanical system

TL;DR

This study investigates how relaxation processes can suppress shot noise in a quantum dot coupled to a nanoelectromechanical oscillator, revealing conditions for noise reduction below half the Fano factor and effects on current depending on bias.

Contribution

It demonstrates that relaxation can qualitatively alter transport properties and suppress shot noise in quantum dots, regardless of electron-phonon coupling strength, supported by a simplified four-state model.

Findings

Relaxation induces shot noise suppression below 1/2 of the Fano factor.

Transport properties depend on relaxation strength and applied voltage.

Results are consistent across different electron-phonon coupling regimes.

Abstract

In this paper we report a relaxation-induced suppression of the noise for a single level quantum dot coupled to an oscillator with incoherent dynamics in the sequential tunneling regime. It is shown that relaxation induces qualitative changes in the transport properties of the dot, depending on the strength of the electron-phonon coupling and on the applied voltage. In particular, critical thresholds in voltage and relaxation are found such that a suppression below 1/2 of the Fano factor is possible. Additionally, the current is either enhanced or suppressed by increasing relaxation, depending on bias being greater or smaller than the above threshold. These results exist for any strength of the electron-phonon coupling and are confirmed by a four states toy model.