Generation of a precise time scale assisted by a near-continuously operating optical lattice clock

We report on the achievement of a reduced time difference in a time scale with respect to Coordinated Universal Time (UTC) by steering a hydrogen-maser-based time scale with a near-continuously operating optical lattice clock. The time scale is generated in a postprocessing analysis for 230 days using a hydrogen maser with its fractional frequency stability limited by a flicker floor of 2×10^-15 and an Yb optical lattice clock operated with an uptime of 81.6%. During the 230-day period, the root-mean-square time difference of our time scale with respect to UTC is 0.52 ns, which is a better performance than those of time scales steered by microwave fountain clocks, which exhibit root-mean-square differences from 0.99 to 1.6 ns. With the high uptime achieved by the Yb optical lattice clock, our simulation results indicate the potential for generating a state-of-the-art time scale with a time difference of $<0.1$ ns over a month using a better hydrogen maser reaching the mid-10^-16 stability level. This work demonstrates that the use of an optical clock with a high uptime enhances the stability of a time scale.