Intermittent optical frequency measurements to reduce the dead time uncertainty of frequency link

Abstract

The absolute frequency of the 87Sr lattice clock transition was evaluated with an uncertainty of 1.1 × 10-15 using a frequency link to the international atomic time (TAI). The frequency uncertainty of a hydrogen maser used as a transfer oscillator was reduced by homogeneously distributed intermittent measurement over a five-day grid of TAI. Three sets of four or five days measurements as well as systematic uncertainty of the clock at 8.6 × 10-17 have resulted in an absolute frequency of 87Sr 1S0-3P0 clock transition to be 429 228 004 229 872.85 (47) Hz.