Cooling of nanomechanical resonator by thermally activated single-electron transport

TL;DR

This paper demonstrates that nanomechanical resonators can be cooled close to their quantum ground state through thermally activated single-electron tunneling, with bias voltage controlling the cooling efficiency.

Contribution

It introduces a novel cooling mechanism for nanomechanical resonators using electron tunneling from an STM tip, highlighting the bias-dependent interplay of electronic and mechanical coupling.

Findings

Achieved near-ground-state cooling with vibron population of 0.2

Cooling is controlled by bias voltage below Coulomb blockade

Interplay of two coupling mechanisms influences vibron emission and absorption

Abstract

We show that the vibrations of a nanomechanical resonator can be cooled to near its quantum ground state by tunnelling injection of electrons from an STM tip. The interplay between two mechanisms for coupling the electronic and mechanical degrees of freedom results in a bias-voltage dependent difference between the probability amplitudes for vibron emission and absorption during tunneling. For a bias voltage just below the Coulomb blockade threshold we find that absorption dominates, which leads to cooling corresponding to an average vibron population of the fundamental bending mode of 0.2.