Coupled quantum dots in bilayer graphene

TL;DR

This paper demonstrates the creation and tunability of single, double, and triple quantum dots in bilayer graphene, highlighting their potential for quantum computing applications due to disorder-free formation and adjustable tunnel barriers.

Contribution

It introduces a versatile method to form and tune multi-quantum dots in bilayer graphene using electrostatic gating and different tunnel barrier mechanisms, advancing quantum device development.

Findings

Quantum dots formed without disorder signs

Tunnel coupling varied over two orders of magnitude

Potential for graphene-based quantum computation

Abstract

Electrostatic confinement of charge carriers in bilayer graphene provides a unique platform for carbon-based spin, charge or exchange qubits. By exploiting the possibility to induce a band gap with electrostatic gating, we form a versatile and widely tunable multi-quantum dot system. We demonstrate the formation of single, double and triple quantum dots that are free of any sign of disorder. In bilayer graphene we have the possibility to form tunnel barriers using different mechanisms. We can exploit the ambipolar nature of bilayer graphene where pn-junctions form natural tunnel barriers. Alternatively, we can use gates to form tunnel barriers, where we can vary the tunnel coupling by more than two orders of magnitude tuning between a deeply Coulomb blockaded system and a Fabry-P\'erot-like cavity. Demonstrating such tunability is an important step towards graphene-based quantum computation.