Electronic Excited States in Bilayer Graphene Double Quantum Dots

TL;DR

This study presents tunneling spectroscopy of bilayer graphene double quantum dots, revealing tunable electronic states, consistent single-particle energy spacing, and magnetic field effects, advancing understanding of quantum behavior in graphene-based nanostructures.

Contribution

It demonstrates detailed characterization of electronic excited states and interdot coupling in bilayer graphene quantum dots using all-graphene gates.

Findings

Constant level spacing of 1.75 meV observed

Tunable interdot coupling energy measured

Electronic excited states evolve with magnetic field

Abstract

We report tunneling spectroscopy experiments on a bilayer graphene double quantum dot device that can be tuned by all-graphene lateral gates. The diameter of the two quantum dots are around 50 nm and the constrictions acting as tunneling barriers are 30 nm in width. The double quantum dot features addition energies on the order of 20 meV. Charge stability diagrams allow us to study the tunable interdot coupling energy as well as the spectrum of the electronic excited states on a number of individual triple points over a large energy range. The obtained constant level spacing of 1.75 meV over a wide energy range is in good agreement with the expected single-particle energy spacing in bilayer graphene quantum dots. Finally, we investigate the evolution of the electronic excited states in a parallel magnetic field.