A Modified Spin Pulsed Readout Method for NV Center Ensembles Reducing Optical Noise

The optical-noise-limited spin readout sensitivity determines the precision of quantum measurement based on nitrogen-vacancy (NV) center. This article investigates the fluorescence dynamics of NV centers by solving the optical rate equations and obtains complete theoretical formulas for the existing optical spin readout method. A transfer coefficient of optical noise to signal noise in the existing differential methods at different frequencies is introduced so as to analyze the optical noise suppression ability and the signal-to-noise ratio (SNR) results under the influence of photon shot noise and optical noise. To further reduce the influence of optical noise on the signal, we propose a modified method to minimize the transfer coefficient by adding a first-order compensation term. Compared with conventional methods, our modified method showed a twofold optical noise suppression ability improvement in the measurement frequency bandwidth. The experiment proves that the final SNR is increased by 43.4% for a long-term measurement. This modified method should lead to immediate improvements in pulsed spin readout of NV center ensembles without extra instrumentation for applications in magnetic field, electric field, and temperature measurements.