Detecting quantum-coherent nanomechanical oscillations using the current-noise spectrum of a double quantum dot

TL;DR

This paper shows how analyzing the current-noise spectrum in a double quantum dot system can reveal quantum coherence and squeezing in a coupled nanomechanical resonator, providing a new method to distinguish classical from quantum behavior.

Contribution

It introduces a novel approach using current noise spectra to detect quantum states and energy spectra of nanomechanical resonators coupled to quantum dots.

Findings

Current noise spectrum distinguishes classical and quantum resonator behavior.

Full frequency noise spectrum reveals combined energy spectrum details.

Regimes with quantum squeezing of the resonator are identified.

Abstract

We consider a nanomechanical resonator coupled to a double quantum dot. We demonstrate how the finite-frequency current noise spectrum through the double quantum dot can be used to distinguish classical and quantum behaviour in the nearby nano-electromechanical resonator. We also show how the full frequency current noise spectrum gives important information on the combined double quantum dot-resonator energy spectrum. Finally, we point out regimes where the quantum state of the resonator becomes squeezed, and also examine the cross-correlated electron-phonon current noise.