Molecule States in a Gate Tunable Graphene Double Quantum Dot

TL;DR

This paper reports on a graphene double quantum dot device with tunable interdot coupling, revealing molecular states and demonstrating high controllability, which is promising for quantum device applications in nuclear-spin-free environments.

Contribution

It introduces a highly controllable graphene double quantum dot system with tunable tunnel coupling and the observation of molecular states, advancing quantum device research.

Findings

Tunable honeycomb charge stability diagrams.

Large interdot tunnel coupling strength observed.

Molecular states extend over the entire double dot.

Abstract

We have measured a graphene double quantum dot device with multiple electrostatic gates that are used to enhance control to investigate it. At low temperatures the transport measurements reveal honeycomb charge stability diagrams which can be tuned from weak to strong interdot tunnel coupling regimes. We precisely extract a large interdot tunnel coupling strength for this system allowing for the observation of tunnel-coupled molecular states extending over the whole double dot. This clean, highly controllable system serves as an essential building block for quantum devices in a nuclear-spin-free world.