Damping of a nanomechanical oscillator strongly coupled to a quantum dot

TL;DR

This paper investigates how a nanomechanical oscillator's damping is affected by strong coupling to a quantum dot, revealing nonlinear damping behavior and asymmetric Coulomb blockade peaks, with potential for excited state spectroscopy.

Contribution

It provides a combined theoretical and experimental analysis of nonlinear damping in a strongly coupled nanomechanical-quantum dot system, highlighting new spectroscopic possibilities.

Findings

Amplitude-dependent nonlinear damping observed.

Asymmetric Coulomb blockade peaks match strong coupling theory.

Predicted excited state spectroscopy via damping measurements.

Abstract

We present theoretical and experimental results on the mechanical damping of an atomic force microscope cantilever strongly coupled to a self-assembled InAs quantum dot. When the cantilever oscillation amplitude is large, its motion dominates the charge dynamics of the dot which in turn leads to nonlinear, amplitude-dependent damping of the cantilever. We observe highly asymmetric lineshapes of Coulomb blockade peaks in the damping that reflect the degeneracy of energy levels on the dot, in excellent agreement with our strong coupling theory. Furthermore, we predict that excited state spectroscopy is possible by studying the damping versus oscillation amplitude, in analogy to varying the amplitude of an ac gate voltage.