Gate Adjustable Coherent Three and Four Level Mixing in a Vertical Quantum Dot Molecule

TL;DR

This study investigates how adjustable gate voltages in a vertical quantum dot molecule influence level mixing, demonstrating control over energy dispersions near level crossings through magneto-resonant-tunneling spectroscopy.

Contribution

It introduces a device with four split gates enabling tunable potential landscapes, allowing precise manipulation of level mixing in a vertical quantum dot system.

Findings

Demonstrated control over three and four level crossings.

Significant alteration of energy dispersions with magnetic field.

Preliminary results showing gate-dependent level mixing.

Abstract

We study level mixing in the single particle energy spectrum of one of the constituent quantum dots in a vertical double quantum dot by performing magneto-resonant-tunneling spectroscopy. The device used in this study differs from previous vertical double quantum dot devices in that the single side gate is now split into four separate gates. Because of the presence of natural perturbations caused by anharmonicity and anistrophy, applying different combinations of voltages to these gates allows us to alter the effective potential landscape of the two dots and hence influence the level mixing. We present here preliminary results from one three level crossing and one four level crossings high up in the energy spectrum of one of the probed quantum dots, and demonstrate that we are able to change significantly the energy dispersions with magnetic field in the vicinity of the crossing regions.