Electric Field Sensing for EDM Experiments.

Nitrogen vacancy diamonds have been proposed for various quantum information devices and were used in a sensitive Bell's theorem test [1]. We describe the status of an electric field sensor using a quantum interference mechanism to enhance its sensitivity. Taking advantage of the linear Stark effect in nitrogen-vacancy diamonds, we use the narrow spectral features associated with the dark states generated via a three-level system (electromagnetically-induced transparency) to measure the energy shifts. The ensemble resolution is typically limited by inhomogeneous broadening caused by the natural $^{\mathrm{13}}$C admixture in the diamond. In one implementation, an all-optical scheme can be realized to provide a compact, fiberized sensing package operating at cryogenic temperatures. [1] B. Hensen, H. Bernien, A. E. Dreau, A. Reiserer, N. Kalb, et al., \textit{Loophole free Bell inequality violation using electron spins separated by 1.3 kilometres}, Nature \textbf{526}, 682 (2015).