Coherent rotation of a single spin via adiabatic half passage in the presence of a ferromagnetic vortex

We experimentally and numerically study possible implementations for π/2 rotations of a single nitrogen-vacancy defect spin state in proximity to a magnetic vortex core. Dynamically controlled magnetic vortex cores have been suggested as a means to provide nanoscale, rapidly-tunable magnetic fields for spin qubit addressability and control. However, driven and thermal non-equilibrium dynamics of the vortex core complicate prospects for high-fidelity gate operations. We find that the complicated profile of the driven vortex core fringe field leads to significant, but unpredictable enhancement of both Zeeman splitting and Rabi frequency. Furthermore, the gyrotropic dynamics of the vortex core lead to a complicated evolution of the spin state. We demonstrate that the fidelity of π/2 rotations can be improved using an adiabatic passage protocol in which the vortex provides an enhancement of spin splitting and Rabi frequency while unwanted vortex dynamics are suppressed.