Inhomogeneous magnetic fields interacting with spinful states in a double quantum dot: Evidence for a staggered spin-orbit interaction

Abstract

The coupling of the spin and the motion of charge carriers is an important ingredient for the manipulation of the spin degree of freedom and for the emergence of topological matter. 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 or for new schemes for spin quantum bits. Realizing this in natural platforms remains a challenge. Using circuit quantum electrodynamics magnetospectroscopy, we investigate the spinful states of a double quantum dot made in a single wall carbon nanotube with lithographically patterned magnetically textured gates. While a full understanding of the behavior of our magnetic textures would be helpful, the experimental signals are consistent with a change of the spin-orbital structure of the states above each gate. The coherence of the data, backed up by extensive theoretical modeling and a control device, points towards the existence of a synthetic staggered spin-orbit interaction in our device.