Non-invasive detection of charge-rearrangement in a quantum dot in high magnetic fields

TL;DR

This paper presents a non-invasive method to detect charge redistribution in a quantum dot under high magnetic fields using a quantum point contact, revealing internal electron rearrangements without changing the electron count.

Contribution

It introduces a device fabricated by local anodic oxidation that independently controls tunneling barriers and detects electron configuration changes in a quantum dot at high magnetic fields.

Findings

Electron redistribution caused by magnetic fields was observed.

Internal electron rearrangements confirmed at fixed electron number.

Quantum dot behavior influenced by Landau shells and spin blockade.

Abstract

We demonstrate electron redistribution caused by magnetic field on a single quantum dot measured by means of a quantum point contact as non-invasive detector. Our device which is fabricated by local anodic oxidation allows to control independently the quantum point contact and all tunnelling barriers of the quantum dot. Thus we are able to measure both the change of the quantum dot charge and also changes of the electron configuration at constant number of electrons on the quantum dot. We use these features to exploit the quantum dot in a high magnetic field where transport through the quantum dot displays the effects of Landau shells and spin blockade. We confirm the internal rearrangement of electrons as function of the magnetic field for a fixed number of electrons on the quantum dot.