Parallel carbon nanotube quantum dots and their interactions

TL;DR

This paper investigates quantum transport in parallel quantum dots within a carbon nanotube rope, revealing tunable interactions and providing insights into inter-dot coupling through experimental and theoretical analysis.

Contribution

It introduces a method to control and analyze inter-dot interactions in a carbon nanotube quantum dot system using a single gate and transport spectroscopy.

Findings

Transport dominated by one quantum dot with additional side dot resonances

Weak gate coupling allows tunability of the quantum dot system

Identification of inter-dot coupling conditions through master equation analysis

Abstract

We present quantum transport measurements of interacting parallel quantum dots formed in the strands of a carbon nanotube rope. In this molecular quantum dot system, transport is dominated by one quantum dot, while additional resonances from parallel side dots appear, which exhibit a weak gate coupling. This differential gating effect provides a tunability of the quantum dot system with only one gate electrode and provides control over the carbon nanotube strand that carries the current. By tuning the system to different states we use quantum transport as a spectroscopic tool to investigate the inter-dot coupling and show a route to distinguish between various side dots. By comparing the experimental data with master equation calculations, we identify conditions for the tunneling rates that are required in order to observe different manifestations of the inter-dot coupling in the transport spectra.