Nitrogen vacancy (NV) diamond solid-state spin systems are highly useful for quantum sensing, however, improving the sensitivity is essential to realizing their potential applications. DC magnetic field sensitivity is typically limited by dephasing of the NV spin state, where the dephasing time (T₂*) limits the experimental sensing time. This invention details a method to improve the sensitivity of NV magnetometers by extending T₂*, resulting in up to 10x improvement in sensitivity and up to 100x decrease in the sensing time required to attain a given measurement. This is achieved by (1) applying RF control of the spin bath surrounding the NV sensor spins, and/or (2) working with differential double quantum (DQ) spin transition, which both rejects common-mode noise sources and enhances sensitivity to magnetic fields. In addition to substantially improving NV magnetometer sensitivity, this method also suppresses sensitivity to non-magnetic signals such as temperature and electric field fluctuations.

NV magnetometers are expected to replace fluxgate magnetometers for field sensing in military, industrial, and commercial applications. Examples include: detection of magnetic anomalies in combat and security environments, magnetic communication for defense and industrial purposes (submarines, mines), orientation and sensing for drilling and mining machines, and magnetic imaging of structures on the sub-micron scale (bio-magnetism and paleomagnetism). Additionally, the invention is expected to be applicable to improving the sensitivity of other solid state spin-based sensors.

This work was published in Physical Review X.