High-sensitivity spin-based electrometry with an ensemble of nitrogen-vacancy centers in diamond

We demonstrate a spin-based, all-dielectric electrometer based on an ensemble of nitrogen-vacancy (NV^-) defects in diamond. An applied electric field causes energy-level shifts symmetrically away from the NV^-'s degenerate triplet states via the Stark effect; this symmetry provides immunity to temperature fluctuations allowing for shot-noise-limited detection. Using an ensemble of NV^-s, we demonstrate shot-noise-limited sensitivities approaching 1 (V/cm)/√Hz under ambient conditions, at low frequencies ($<10$ Hz), and over a large dynamic range (20 dB). A theoretical model for the ensemble of NV^-s fits well with measurements of the ground-state electric susceptibility parameter k_⊥. Implications of spin-based, dielectric sensors for micron-scale electric-field sensing are discussed.