We demonstrate a cavity-enhanced room-temperature magnetic field sensor based on nitrogen-vacancy centers in diamond. Magnetic resonance is detected using absorption of light resonant with the 1042 nm spin-singlet transition. The diamond is placed in an external optical cavity to enhance the absorption, and significant absorption is observed even at room temperature. We demonstrate a magnetic field sensitivity of 2.5nT/Hz, and project a photon shot-noise-limited sensitivity of 70pT/Hz for a few mW of infrared light, and a quantum projection-noise-limited sensitivity of 250fT/Hz for the sensing volume of ∼90μm×90μm×200μm. © 2014 American Physical Society.
Jensen, K., Leefer, N., Jarmola, A., Dumeige, Y., Acosta, V., Kehayias, P., …Budker, D. (2014). Cavity-enhanced room-temperature magnetometry using absorption by nitrogen-vacancy centers in diamond. Physical Review Letters, 112(16), 160802. https://doi.org/10.1103/PhysRevLett.112.160802