Magnetic Resonance in Defect Spins mediated by Spin Waves

TL;DR

This paper analyzes how spin waves in a YIG film can significantly enhance the magnetic resonance coupling with NV centers, providing a theoretical foundation that aligns with recent experimental findings.

Contribution

It offers an analytical calculation of the magnetic field from spin waves and demonstrates the dramatic coupling enhancement compared to direct antenna driving.

Findings

Spin waves substantially increase NV center coupling.

Analytical model matches experimental coupling enhancement.

YIG film spin waves enable longer-range quantum control.

Abstract

In search of two level quantum systems that implement a qubit, the nitrogen-vacancy (NV) center in diamond has been intensively studied for years. Despite favorable properties such as remarkable defect spin coherence times, the addressability of NV centers raises some technical issues. The coupling of a single NV center to an external driving field is limited to short distances, since an efficient coupling requires the NV to be separated by only a few microns away from the source. As a way to overcome this problem, an enhancement of coherent coupling between NV centers and a microwave field has recently been experimentally demonstrated using spin waves propagating in an adjacent yttrium iron garnet (YIG) film [1]. In this paper we analyze the optically detected magnetic resonance spectra that arise when an NV center is placed on top of a YIG film for a geometry similar to the one in the experiment. We analytically calculate the oscillating magnetic field of the spin wave on top of the YIG surface to determine the coupling of spin waves to the NV center. We compare this coupling to the case when the spin waves are absent and the NV center is driven only with the antenna field and show that the calculated coupling enhancement is dramatic and agrees well with the one obtained in the recent experiment.