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Frequency Ratio of (199)Hg and (87)Sr Optical Lattice Clocks beyond the SI Limit
Kazuhiro Yamanaka1,2,3, Noriaki Ohmae1,2,3, Ichiro Ushijima1,2
1Quantum Metrology Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan.
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.
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