title: Two-photon frequency comb spectroscopy of the 6s-8s transition in cesium.
abstract: We report a new absolute frequency measurement of the Cs 6s-8s two-photon transition measured using frequency comb spectroscopy. The fractional frequency uncertainty is 5x10(-11), a factor of 6 better than previous results. The comb is derived from a stabilized picosecond laser and referenced to an octave-spanning femtosecond frequency comb. The relative merits of picosecond-based frequency combs are discussed, and it is shown that the AC Stark shift of the transition is determined by the average rather than the much larger peak intensity.
authors.affiliation: Max-Planck-Institut für Quantenoptik, Garching, Germany. peter.fendel@mpq.mpg.de
authors.forename: P
authors.initials: P
authors.lastname: Fendel
authors.forename: S D
authors.initials: SD
authors.lastname: Bergeson
authors.forename: Th
authors.initials: T
authors.lastname: Udem
authors.forename: T W
authors.initials: TW
authors.lastname: Hänsch