Measuring the frequency of a Sr optical lattice clock using a 120-km coherent optical transfer

Abstract

We demonstrate a precision frequency measurement using a phase-stabilized 120-km optical fiber link over a physical distance of 50 km. The transition frequency of the 87Sr optical lattice clock at the University of Tokyo is measured to be 429228004229874.1(2.4) Hz referenced to international atomic time (TAI). The measured frequency agrees with results obtained in Boulder and Paris at a 6*10^-16 fractional level, which matches the current best evaluations of Cs primary frequency standards. The results demonstrate the excellent functions of the intercity optical fibre link, and the great potential of optical lattice clocks for use in the redefinition of the second.

14 pages, 3 figures

References in corpus (6)

• Sr lattice clock at 1x10^{-16} fractional uncertainty by remote optical evaluation with a Ca clock
• The absolute frequency of the 87Sr optical clock transition
• 86-km optical link with a resolution of 2.10-18 for RF frequency transfer
• Coherent optical phase transfer over a 32-km fiber with 1-s instability at $10^{-17}$
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• An Optical Lattice Clock with Spin-polarized 87Sr Atoms