Non-collinear spin-orbit magnetic fields in a carbon nanotube double quantum dot

TL;DR

This paper experimentally demonstrates non-collinear spin-orbit magnetic fields in a curved carbon nanotube double quantum dot, revealing detailed spin structures and potential for unconventional superconductivity and entanglement detection.

Contribution

It provides the first experimental realization and analysis of non-collinear intrinsic spin-orbit magnetic fields in a curved carbon nanotube quantum dot system.

Findings

Identification of near four-fold degenerate shell structure

Determination of four unique spin directions for quantum states

Analysis of spin-orbit coupling and inter-segment angle

Abstract

We demonstrate experimentally that non-collinear intrinsic spin-orbit magnetic fields can be realized in a curved carbon nanotube two-segment device. Each segment, analyzed in the quantum dot regime, shows near four-fold degenerate shell structure allowing for identification of the spin-orbit coupling and the angle between the two segments. Furthermore, we determine the four unique spin directions of the quantum states for specific shells and magnetic fields. This class of quantum dot systems is particularly interesting when combined with induced superconducting correlations as it may facilitate unconventional superconductivity and detection of Cooper pair entanglement. Our device comprises the necessary elements.