@article { , title = {Cavity-enhanced room-temperature magnetometry using absorption by nitrogen-vacancy centers in diamond}, abstract = {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.}, doi = {10.1103/PhysRevLett.112.160802}, eissn = {1079-7114}, issn = {0031-9007}, issue = {16}, journal = {Physical Review Letters}, pages = {160802}, publicationstatus = {Published}, publisher = {American Physical Society}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.112.160802}, volume = {112}, year = {2014}, author = {Jensen, K. and Leefer, N. and Jarmola, A. and Dumeige, Y. and Acosta, V.?M. and Kehayias, P. and Patton, B. and Budker, D.} }