Single Spin Detection with a Carbon Nanotube Double Quantum Dot

TL;DR

This paper demonstrates direct measurement and control of singlet-triplet exchange coupling in carbon nanotube quantum dots, exploring spin interactions, spin-orbit effects, and impurity sensitivity crucial for quantum information applications.

Contribution

It introduces a method to measure and control spin interactions in carbon nanotube quantum dots, advancing understanding of spin coupling and environmental effects.

Findings

Controlled singlet-triplet exchange coupling demonstrated

Effects of spin-orbit interaction on electron transitions elucidated

Interaction with a single impurity spin investigated

Abstract

Spin qubits defined in carbon nanotube quantum dots are of considerable interest for encoding and manipulating quantum information because of the long electron spin coherence times expected. However, before carbon nanotubes can find applications in quantum information processing schemes, we need to understand and control the coupling between individual electron spins and the interaction between the electron spins and their environment. Here we make use of spin selection rules to directly measure - and demonstrate control of - the singlet-triplet exchange coupling between two carbon nanotube quantum dots. We furthermore elucidate the effects of spin-orbit interaction on the electron transitions and investigate the interaction of the quantum dot system with a single impurity spin - the ultimate limit in spin sensitivity.