Sensing the Local Charge and Strain Environment of Nitrogen Vacancy Centers in Diamond

The Nitrogen Vacancy (NV) center in diamond has emerged as a promising candidate for nanoscale sensing, in part, because of its sensitivity to a myriad of external parameters. However, coupling to local \emph{internal} strain and electric fields (i.e. in the diamond host) can suppress this sensitivity to external signals. This is especially important in high density ensembles, where one leverages spin correlations to perform enhanced spectroscopy. We demonstrate that in such samples, spectral features typically attributed to internal strain in fact result from electric fields originating from local charged defects. We distinguish between the effects of strain and electric fields by using diamond anvil cells to characterize the elastic response of NV centers in the gigapascal regime. Under these conditions, we investigate the charge dynamics of the NV center and reconstruct the complete strain tensor within the anvil cell.