An atomic time scale is a method for marking events and the passage of time by using atomic frequency standards. Thanks to the superior performance of atomic clocks based on optical transitions, time scales generated with optical clocks have the potential to be more accurate and stable than those based on microwave clocks. In this work, we demonstrate an experimental optical time scale based on the INRiM Yb optical lattice clock and a hydrogen maser as a flywheel oscillator, showing sub-nanosecond accuracy over months-long periods and nanosecond accuracy over a 1-year period. The obtained results show that optical time scales have competitive performances even when the optical clock has a limited and non-uniformly distributed up-time. Consequently, we are working to include the Yb clock within the ensemble of clocks routinely used for the generation of the Italian time scale. Furthermore, these results represent a crucial step towards the future redefinition of the second of the International System of Units based on an optical transition.

中文翻译：

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具有亚纳秒能力的长达一年的光学时标

原子时标是一种使用原子频率标准来标记事件和时间流逝的方法。由于基于光学跃迁的原子钟具有卓越的性能，光学钟产生的时标有可能比基于微波钟的时标更加准确和稳定。在这项工作中，我们展示了基于 INRiM Yb 光学晶格钟和氢微波激射器作为飞轮振荡器的实验光学时标，显示出数月内的亚纳秒精度和一年内的纳秒精度。所得结果表明，即使光时钟的正常运行时间有限且分布不均匀，光时标也具有竞争性的性能。因此，我们正在努力将 Yb 时钟纳入通常用于生成意大利时间刻度的时钟集合中。此外，这些结果代表了未来基于光学跃迁重新定义国际单位制第二个的关键一步。