title: Suppression of spin projection noise in broadband atomic magnetometry.
abstract: We demonstrate that quantum nondemolition measurement, combined with a suitable parameter estimation procedure, can improve the sensitivity of a broadband atomic magnetometer by reducing uncertainty due to spin projection noise. Furthermore, we provide evidence that real-time quantum feedback control offers robustness to classical uncertainties, including shot-to-shot atom number fluctuations, that would otherwise prevent quantum-limited performance.
authors.affiliation: Physics and Control & Dynamical Systems, California Institute of Technology, Pasadena California 91125, USA. jgeremia@Caltech.EDU
authors.forename: J M
authors.initials: JM
authors.lastname: Geremia
authors.forename: John K
authors.initials: JK
authors.lastname: Stockton
authors.forename: Hideo
authors.initials: H
authors.lastname: Mabuchi