Title: Coupling and control of defect spin qubits via an engineered magnetic environment

Jesse Berezovsky, Dept. of Physics, Case Western Reserve University

Abstract: Defect spin qubits, such as the nitrogen-vacancy (NV) defect in diamond, perform splendidly as single qubits. With a coherence time that can exceed 1 s at room temperature, defect spins provide an excellent basis for single qubit devices, such as nanoscale magnetometers. But to go beyond single qubits, we require an efficient scalable platform for controlling defect spin qubit registers, and controllably coupling qubits to engineer entanglement. In this talk, I will describe recent advances in our understanding of how magnetic materials and structures couple to defect spin qubits, and how this opens an avenue towards engineering the magnetic environment of the spins for control and coupling. Topological magnetization states such as magnetic vortices provide strong, local magnetic field gradients that can be controlled dynamically for addressable control of qubits [1]. Coupling between qubits may be enabled by a magnon-mediated process. On the other hand, spin-magnon interactions can lead to enhanced spin relaxation or decoherence (e.g. [2]). I will review recent work exploring the interactions of defect spins with magnons in adjacent magnetic structures and discuss the implications for proposed technologies incorporating coherent spins with proximal magnetic elements.

[1] Wolf, M. S., Badea, R., and Berezovsky, J. “Fast, Nanoscale Addressability of Nitrogen-Vacancy Spins via Coupling to a Dynamic Ferromagnetic Vortex” Nature Communications 7, (2016): 5.

[2] Trimble, J., Gould, B., Heremans, F. J., Zhang, S. S.-L., Awschalom, D. D., amd Berezovsky, J. “Relaxation of a single defect spin by the low-frequency gyrotropic mode of a magnetic vortex” J. Appl. Phys. 130, (2021).