RF-photonic links for cryogenic-compatible microwave control in quantum networks and applications to magnetometry

Abstract

We present an RF-over-fiber (RFoF)-centered experimental platform for optically detected magnetic resonance (ODMR) of nitrogen-vacancy (NV) centers in diamond, motivated by the need for remote, electrically isolated, and cryo-compatible microwave delivery in future quantum sensing systems. Conventional coax-fed ODMR measurements are first used to establish the baseline dependence of resonance contrast and linewidth on microwave power, as well as the magnetic-field- and angle-dependent spectral response of the NV ensemble. In the baseline configuration, the ODMR contrast exceeds 11% at 25 dBm microwave drive, while magnetic-field and orientation sweeps confirm the expected Zeeman splitting and field-projection dependence of the ensemble response. These reference measurements are then used to benchmark a 1310 nm intensity-modulated RFoF link in which the microwave drive is transported over optical fiber and recovered at the sensing node using a high-speed photodiode. Under remote photonic delivery, the recovered signal reproduces the characteristic Zeeman-split ODMR response of the NV ensemble over the low-field regime studied. At a recovered RF power of −5.5 dBm, the RFoF-driven ODMR contrast remains in the 0.6–0.9% range, while at a higher-power operating point of −0.7 dBm the contrast increases to greater than 2.2%. The corresponding overall power-conversion efficiencies are 3.42% and 2.52%, respectively. These results establish that photonic microwave transport can preserve physically meaningful NV ODMR signatures while providing a practical route toward remote microwave delivery, reduced electromagnetic interference, and future thermally constrained or cryogenic spin-control architectures.