Nanoscale magnetometry with nitogen-vacancy color centers in diamond

The ability to sense and spatially resolve magnetic fields at nanometer dimensions is key to understanding many fundamental physical processes and has a wide range of applications in materials science, biology, and medicine. Our novel approach to nanoscale sensing is based on coherent control of individual electronic spins associated with the nitrogen-vacany (NV) center in diamond. In this work, we describe proof-of-principle experimental measurements of time-varying magnetic fields using single NV$^{-}$ centers in bulk crystalline diamond and sub-100 nm diamond nanocrystals. Using spin echo spectroscopy techniques on the spin triplet electronic ground state, we sense magnetic fields with frequencies from 3kHz to 15 kHz to a resolution approaching 100 $\mu$Gauss.