Absolute frequency of ${}^{87}\mathrm{Sr}$ at $1.8\times 10^{-16}$ uncertainty by reference to remote Primary Frequency Standards

Abstract

The optical lattice clock NICT-Sr1 regularly reports calibration measurements of the international timescale TAI. By comparing measurement results to the reports of eight Primary Frequency Standards, we find the absolute frequency of the ${}^{87}\mathrm{Sr}$ clock transition to be f(Sr)=$429228004229873.082(76)$, with a fractional uncertainty of less than 1.8x10${}^{-16}$ approaching the systematic limits of the best realization of SI second. Our result is consistent with other recent measurements and further supported by the loop closure over the absolute frequencies of ${}^{87}\mathrm{Sr}$, ${}^{171}\mathrm{Yb}$ and direct optical measurements of their ratio.

arXiv comment18 pages, 5 figures, 5 tables

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Cited by in corpus (12)

• Roadmap towards the redefinition of the second
• An Optical Atomic Clock Based on a Highly Charged Ion
• Optical frequency ratio of a ${}^{171}{\mathrm{Yb}}^{+}$ single-ion clock and a ${}^{87}\mathrm{Sr}$ lattice clock
• Absolute frequency measurement of the 171Yb optical lattice clock at KRISS using TAI for over a year
• Frequency ratio of an ${}^{115}$In${}^{+}$ ion clock and a ${}^{87}$Sr optical lattice clock
• Absolute frequency measurement of a Yb optical clock at the limit of the Cs fountain
• Atomic clocks highly sensitive to the variation of the fine structure constant based on Hf II, Hf IV, and W VI ions
• Absolute frequency measurements with a robust, transportable ^{40}Ca^{+} optical clock
• Continuous optical generation of microwave signals for fountain clocks
• Improved absolute frequency measurement of ${}^{171}$Yb at NMIJ with uncertainty below $2\times 10^{-16}$
• Absolute frequency measurement of a Lu${}^{+}$ ${(}^3{\mathrm{D}}_1)$ optical frequency standard via link to international atomic time
• A High-frequency Geodetic VLBI Experiment for Optical Clock Comparison