Cooling a vibrational mode coupled to a molecular single-electron transistor

TL;DR

This paper investigates how a molecular single-electron transistor can cool its vibrational mode by electron transport, with efficiency depending on bias conditions and electron-phonon coupling, potentially lowering the mode's temperature.

Contribution

It introduces a mechanism for cooling vibrational modes via electron transport in a molecular transistor, analyzing optimal conditions for maximum cooling efficiency.

Findings

Cooling occurs when electron temperature is lower than phonon temperature.

Optimal electron-phonon coupling maximizes cooling efficiency.

Final vibrational temperature varies with bias conditions.

Abstract

We consider a molecular single electron transistor coupled to a vibrational mode. For some values of the bias and gate voltage transport is possible only by absorption of one ore more phonons. The system acts then as a cooler for the mechanical mode at the condition that the electron temperature is lower than the phonon temperature. The final effective temperature of the vibrational mode depends strongly on the bias conditions and can be lower or higher of the reservoir in contact with the oscillator. We discuss the efficiency of this method, in particular we find that there is an optimal value for the electron-phonon coupling that maximizes cooling.