Optically Enhanced Electric Field Sensing Using Nitrogen-Vacancy Ensembles

Nitrogen-vacancy (N-V) centers in diamond have shown promise as inherently localized electric field sensors, capable of detecting individual charges with nanometer resolution. Working with N-V ensembles, we demonstrate that a detailed understanding of the internal electric field environment enables enhanced sensitivity in the detection of external electric fields. We follow this logic along two complementary paths. First, using excitation tuned near the N-V's zero-phonon line, we perform optically detected magnetic resonance (ODMR) spectroscopy at cryogenic temperatures in order to precisely measure the N-V center's excited-state susceptibility to electric fields. In doing so, we demonstrate that the characteristically observed contrast inversion arises from an interplay between spin-selective optical pumping and the N-V centers' local charge distribution. Second, motivated by this understanding, we propose and analyze a method for optically enhanced electric field sensing using N-V ensembles; we estimate that our approach should enable order-of-magnitude improvements in the dc electric field sensitivity.