Coupling symmetry of quantum dot states

TL;DR

This paper investigates the symmetry of tunneling rates in a quantum dot using non-invasive charge detection, revealing how coupling symmetry depends on the number and spatial distribution of states involved.

Contribution

It introduces a non-invasive method to analyze tunneling rate symmetry in quantum dots and explores how this symmetry varies with state number and spatial distribution.

Findings

Identified a symmetry line where tunneling rates to source and drain are equal.

Coupling symmetry depends on the number of states contributing to transport.

Spatial distribution of states influences the coupling symmetry.

Abstract

With non-invasive methods, we investigate ground and excited states of a lateral quantum dot. Charge detection via a quantum point contact is used to map the dot dynamics in a regime where the current through the dot is too low for transport measurements. In this way we investigate and compare the tunneling rates from the dot to source and drain. We find a symmetry line on which the tunneling rates to both leads are equal. In this situation ground states as well as excited states influence the mean charge of the dot. A detailed study in this regime reveals that the coupling symmetry depends on the number of states contributing to transport and on the spatial distribution of individual states.