Diamond NV centers based quantum sensor using a VCO integrated with filtering antenna

This article presents a diamond nitrogen-vacancy (NV) center-based magnetic field sensor using a voltage-controlled oscillator (VCO) integrated with a filtering antenna. In existing NV-based quantum sensing systems, microwave source and delivery units are implemented by a set of bulky and costly instruments. This limits its practical applications as well as portability. Here, a VCO integrated with the filtering antenna is designed, providing a more uniform, efficient, broadband and lower phase noise microwave field coupling to the NV centers. As a result, the sensitivity and the dynamic range have been improved over the conventional scheme using separate microwave components, such as antennas, transmission lines, and resonators. Moreover, in this work, the optic filter and photodetector are also integrated using the hybrid microwave integrated circuits (HMICs) technique for the first time. This significantly increases the integration level and reduces the cost of the NV-based magnetometers. The experimental results indicate that our VCO integrated filtering antenna achieves a sensitivity of 8.52 μT /Hz ^1/2 and a dynamic range up to 32.73 dB, which are both greatly improved compared to the VCO with a single resonator. This validates the effectiveness of the approach.