Coherent control of solid-state defect spins via patterned boron-doped diamond circuit

Monolithic integration, which refers to the incorporation of all device functionalities within a single material, shows significant potential for creating scalable solid-state quantum devices. This study demonstrated the coherent control of nitrogen-vacancy (NV) spins using an electronic circuit monolithically integrated within diamond: a patterned, conductive boron-doped diamond (BDD) microwave waveguide. First, we validated the high-frequency performance of the circuit by characterizing its impedance up to the microwave range, confirming its capability for efficient microwave transmission. Then, using this monolithically integrated BDD--NV hybrid system, we performed optically detected magnetic resonance and observed noticeable Rabi oscillations driven by the metallic BDD circuit. Importantly, we verified that the BDD antenna has a minimal detrimental impact on the NV spins; microwave-induced heating is negligible under both pulsed and continuous driving, and the spin relaxation time $T₁$ remains unperturbed. This approach paves the way for a new class of compact, robust, and versatile quantum platforms suitable for sensing and information processing in various environments.