Energy-dependent tunnelling from few-electron dynamic quantum dots

TL;DR

This study measures electron escape rates from dynamic quantum dots influenced by Coulomb interactions, revealing how tunnelling depends on electron number and estimating addition energies using a saddle-point model.

Contribution

It introduces a method to extract tunnelling rates from dynamic quantum dots and demonstrates their dependence on electron number and Coulomb energy.

Findings

Tunnelling rates vary by an order of magnitude with gate voltage.

Tunnelling rates depend on the number of electrons due to Coulomb energy.

Addition energies for the second and third electrons are estimated to be a few meV.

Abstract

We measure the electron escape-rate from surface-acoustic-wave dynamic quantum dots (QDs) through a tunnel barrier. Rate-equations are used to extract the tunnelling rates, which change by an order of magnitude with tunnel-barrier gate voltage. We find that the tunnelling rates depend on the number of electrons in each dynamic QD because of Coulomb energy. By comparing this dependence to a saddle-point-potential model, the addition energies of the second and third electron in each dynamic QD are estimated. The scale (a few meV) is comparable to those in static QDs as expected.