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 2.5  nT/Hz, and project a photon shot-noise-limited sensitivity of 70  pT/Hz for a few mW of infrared light, and a quantum projection-noise-limited sensitivity of 250  fT/Hz for the sensing volume of ∼90  μm×90  μm×200  μm.
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA.
authors.forename: K
authors.initials: K
authors.lastname: Jensen
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA.
authors.forename: N
authors.initials: N
authors.lastname: Leefer
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA.
authors.forename: A
authors.initials: A
authors.lastname: Jarmola
authors.affiliation: Université de Rennes 1, CNRS, UMR 6082 FOTON, Enssat, 6 rue de Kerampont, CS 80518, 22305 Lannion cedex, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Dumeige
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA.
authors.forename: V M
authors.initials: VM
authors.lastname: Acosta
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA.
authors.forename: P
authors.initials: P
authors.lastname: Kehayias
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA and Physik-Department, Technische Universität München, 85748 Garching, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Patton
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720-7300, USA.
authors.forename: D
authors.initials: D
authors.lastname: Budker