Mechanically probing coherent tunnelling in a double quantum dot

TL;DR

This paper theoretically investigates how the interaction between a double quantum dot's charge dynamics and a capacitively-coupled AFM cantilever can be used to sensitively probe coherent tunnelling and extract key quantum parameters.

Contribution

It introduces a method to use cantilever frequency shifts and damping to quantitatively measure coherent inter-dot tunnelling and T_1 times in double quantum dots.

Findings

Cantilever frequency shift and damping are sensitive probes of inter-dot tunnelling.

The method allows quantitative extraction of tunnelling magnitude.

Adiabatic modulation leads to new effects compared to single-dot systems.

Abstract

We study theoretically the interaction between the charge dynamics of a few-electron double quantum dot and a capacitively-coupled AFM cantilever, a setup realized in several recent experiments. We demonstrate that the dot-induced frequency shift and damping of the cantilever can be used as a sensitive probe of coherent inter-dot tunnelling, and that these effects can be used to quantitatively extract both the magnitude of the coherent interdot tunneling and (in some cases) the value of the double-dot T_1 time. We also show how the adiabatic modulation of the double-dot eigenstates by the cantilever motion leads to new effects compared to the single-dot case.