Absolute frequency measurement of the 87Sr optical lattice clock at NTSC using international atomic time

Abstract

Abstract We report the absolute frequency measurement of the 5 s 2 1 S 0 → 5 s 5 p 3 P 0 transition in 87Sr optical lattice clock (Sr1) at National Time Service Center. Its systematic frequency shifts are evaluated carefully with a total relative uncertainty of 5.1 × 10 − 17 . The measured absolute frequency is 429 228 004 229 872.91(18) Hz with a relative uncertainty of 4.1 × 10 − 16 , with reference to the ensemble of primary and secondary frequency standards published in the Circular T bulletin by BIPM through a global navigation satellite system link.