Staggered spin-orbit interaction in a nanoscale device

TL;DR

This paper demonstrates a method to engineer staggered spin-orbit interaction in a nanoscale device using lithographically patterned magnetic gates and a carbon nanotube double quantum dot, enabling control over topological states.

Contribution

It introduces a novel approach to create synthetic staggered spin-orbit interaction via magnetic gating in a carbon nanotube quantum dot system.

Findings

Achieved engineered staggered spin-orbit interaction with a change larger than the hopping energy.

Demonstrated control of wave functions across a domain wall via light-matter coupling.

Showed potential for topological quantum computing applications.

Abstract

The coupling of the spin and the motion of charge carriers stems directly from the atomic structure of a conductor. It has become an important ingredient for the emergence of topological matter, and, in particular, topological superconductivity which could host non-abelian excitations such as Majorana modes or parafermions. These modes are sought after mostly in semiconducting platforms which are made of heavy atoms and therefore exhibit naturally a large spin-orbit interaction. Creating domain walls in the spin orbit interaction at the nanoscale may turn out to be a crucial resource for engineering topological excitations suitable for universal topological quantum computing. For example, it has been proposed for exploring exotic electronic states or for creating hinge states. Realizing this in natural platforms remains a challenge. In this work, we show how this can be alternatively implemented by using a synthetic spin orbit interaction induced by two lithographically patterned magnetically textured gates. By using a double quantum dot in a light material -- a carbon nanotube -- embedded in a microwave cavity, we trigger hopping between two adjacent orbitals with the microwave photons and directly compare the wave functions separated by the domain wall via the light-matter coupling. We show that we can achieve an engineered staggered spin-orbit interaction with a change of strength larger than the hopping energy between the two sites.