Single wall carbon nanotube double quantum dot

TL;DR

This paper demonstrates the creation and analysis of a tunable double quantum dot system in a semiconducting single wall carbon nanotube, using top-gate electrodes and electrostatic modeling to characterize its properties.

Contribution

It introduces a method to define and analyze coupled quantum dots in a single wall carbon nanotube with detailed electrostatic characterization.

Findings

Bias spectroscopy yields addition energies of the quantum dots.

Honeycomb charge stability diagrams are successfully modeled.

Coupling energy between the quantum dots is quantitatively extracted.

Abstract

We report on two top-gate defined, coupled quantum dots in a semiconducting single wall carbon nanotube, constituting a tunable double quantum dot system. The single wall carbon nanotubes are contacted by titanium electrodes, and gated by three narrow top-gate electrodes as well as a back-gate. We show that a bias spectroscopy plot on just one of the two quantum dots can be used to extract the addition energy of both quantum dots. Furthermore, honeycomb charge stability diagrams are analyzed by an electrostatic capacitor model that includes cross capacitances, and we extract the coupling energy of the double quantum dot.