title: Optical atomic coherence at the 1-second time scale.
abstract: Highest-resolution laser spectroscopy has generally been limited to single trapped ion systems because of the rapid decoherence that plagues neutral atom ensembles. Precision spectroscopy of ultracold neutral atoms confined in a trapping potential now shows superior optical coherence without any deleterious effects from motional degrees of freedom, revealing optical resonance linewidths at the hertz level with a good signal-to-noise ratio. The resonance quality factor of 2.4 x 10(14) is the highest ever recovered in any form of coherent spectroscopy. The spectral resolution permits direct observation of the breaking of nuclear spin degeneracy for the 1S0 and 3P0 optical clock states of 87Sr under a small magnetic bias field. This optical approach for excitation of nuclear spin states allows an accurate measurement of the differential Landé g factor between 1S0 and 3P0. The optical atomic coherence demonstrated for collective excitation of a large number of atoms will have a strong impact on quantum measurement and precision frequency metrology.
authors.affiliation: JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309-0440, USA.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Boyd
authors.forename: Tanya
authors.initials: T
authors.lastname: Zelevinsky
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Ludlow
authors.forename: Seth M
authors.initials: SM
authors.lastname: Foreman
authors.forename: Sebastian
authors.initials: S
authors.lastname: Blatt
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ido
authors.forename: Jun
authors.initials: J
authors.lastname: Ye