T-2-limited sensing of static magnetic fields via fast rotation of quantum spins

Abstract

Diamond-based quantum magnetometers are more sensitive to oscillating (ac) magnetic fields than static (dc) fields because the crystal impurity-induced ensemble dephasing time T2∗, the relevant sensing time for a dc field, is much shorter than the spin coherence time T2, which determines the sensitivity to ac fields. Here we demonstrate measurement of dc magnetic fields using a physically rotating ensemble of nitrogen-vacancy centers at a precision ultimately limited by T2 rather than T2∗. The rotation period of the diamond is comparable to T2 and the angle between the nitrogen-vacancy (NV) axis and the target magnetic field changes as a function of time, thus upconverting the static magneti..