Coherent properties of nano-electromechanical systems

TL;DR

This paper explores the coherent regime of nano-electromechanical systems, revealing regimes with effective cooling and strong coherence effects, including sub-Poissonian vibrational states and reduced quadratures.

Contribution

It introduces a master equation approach that captures vibrational coherences, identifying regimes with effective cooling and strong quantum coherence effects.

Findings

Identification of two regimes: effective thermal state and strong coherence

Observation of vibrational cooling with sub-Poissonian vibron Fano factor

Reduction of position and momentum quadratures indicating quantum coherence

Abstract

We study the properties of a nano-electromechanical system in the coherent regime, where the electronic and vibrational time scales are of the same order. Employing a master equation approach, we obtain the stationary reduced density matrix retaining the coherences between vibrational states. Depending on the system parameters, two regimes are identified, characterized by either ($i$) an {\em effective} thermal state with a temperature {\em lower} than that of the environment or ($ii$) strong coherent effects. A marked cooling of the vibrational degree of freedom is observed with a suppression of the vibron Fano factor down to sub-Poissonian values and a reduction of the position and momentum quadratures.