title: Precision spectroscopy and density-dependent frequency shifts in ultracold Sr.
abstract: By varying the density of an ultracold 88Sr sample from 10(9) to>10(12) cm(-3), we make the first definitive measurement of the density-related frequency shift and linewidth broadening of the 1S0-3P1 optical clock transition in an alkaline earth system. In addition, we report the most accurate measurement to date of the 88Sr 1S0-3P1 optical clock transition frequency. Including a detailed analysis of systematic errors, the frequency is [434 829 121 312 334+/-20(stat)+/-33(syst)] Hz.
authors.affiliation: JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ido
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Loftus
authors.forename: Martin M
authors.initials: MM
authors.lastname: Boyd
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Ludlow
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Holman
authors.forename: Jun
authors.initials: J
authors.lastname: Ye