Bias-field-free operation of nitrogen-vacancy ensembles for vector magnetometry - Adrian Solyom

Accurate measurements of vector magnetic fields are critically important to applications in mining exploration, geoscience, and navigation. Nitrogen-vacancy (NV) centers in diamond offer an attractive platform with native vector sensing capabilities since the ensemble will respond to magnetic components associated with each of the four distinct crystal bonds. Reconstruction of the vector field requires isolating the signals from each group, however the traditional method of applying a bias field to lift the degeneracy leaves the magnetometer susceptible to bias drifts that are indistinguishable from changes in the external magnetic field. In this talk, I will present our approach to performing bias-field-free vector magnetometry that labels the signal from each NV orientation using the direction of the microwave (MW) field in a variable-pulse-duration Ramsey scheme. Simulations demonstrate that each orientation’s signal can be isolated with subnanotesla accuracy in most terrestrial fields, even without precise MW calibration and with only a moderate cost to sensitivity. We experimentally validate the concept by observing relevant features that evolve as expected with changes in the applied field. Our findings lay the groundwork for high-accuracy or long-duration missions with portable vector magnetometers.