Modified Split Ring Resonators for Efficient and Homogeneous Microwave Control of Large Volume Spin Ensembles

TL;DR

This paper introduces a modified split-ring resonator design that significantly improves microwave control homogeneity and strength over large volumes for nitrogen-vacancy centers in diamond, advancing quantum sensing capabilities.

Contribution

The paper presents a novel split-ring resonator design that enhances microwave drive homogeneity and strength for large volume quantum sensors, enabling higher sensitivity.

Findings

Achieved Rabi frequencies up to 18 MHz

Enhanced drive homogeneity with less than 0.7% inhomogeneity

Demonstrated effective control over a 0.1 mm^3 volume

Abstract

Quantum sensing using local defects in solid-state systems has gained significant attention over the past several years, with impressive results demonstrated both in Academia and in Industry. Specifically, employing large volume and high density ensembles for beyond state-of-the-art sensitives is of clear interest. A major obstacle for achieving such record sensitivities is associated with the need to realize strong, homogeneous driving of the sensor defects. Here we focus on high-frequency microwave sensing using nitrogen-vacancy centers in diamond, and develop a modified split-ring resonator design to address this issue. We demonstrate enhanced drive strengths and homogeneities over large volumes compared to previous results, with prospects for enabling the desired sensitivities. We reach Rabi frequencies of up to 18 [MHz] with an efficiency ratio of 2 [$Gauss/\sqrt{Watt}$], along with an inhomogeneity of $<0.7\%$ in a volume of $0.1\:mm^3$.