title: Frequency Ratio of (199)Hg and (87)Sr Optical Lattice Clocks beyond the SI Limit.
abstract: We report on a frequency ratio measurement of a (199)Hg-based optical lattice clock referencing a (87)Sr-based clock. Evaluations of lattice light shift, including atomic-motion-dependent shift, enable us to achieve a total systematic uncertainty of 7.2×10(-17) for the Hg clock. The frequency ratio is measured to be νHg/νSr=2.629 314 209 898 909 60(22) with a fractional uncertainty of 8.4×10(-17), which is smaller than the uncertainty of the realization of the International System of Units (SI) second, i.e., the SI limit.
authors.affiliation: Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan.|Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656, Japan.|Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamanaka
authors.affiliation: Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan.|Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656, Japan.|Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ohmae
authors.affiliation: Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan.|Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Ushijima
authors.affiliation: Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan.|Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Takamoto
authors.affiliation: Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan.|Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656, Japan.|Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Katori