Deployed optical clocks will improve positioning for navigational autonomy¹, provide remote time standards for geophysical monitoring² and distributed coherent sensing³, allow time synchronization of remote quantum networks^4,5 and provide operational redundancy for national time standards. Although laboratory optical clocks now reach fractional inaccuracies below 10⁻¹⁸ (refs. ^6,7), transportable versions of these high-performing clocks^8,9 have limited utility because of their size, environmental sensitivity and cost¹⁰. Here we report the development of optical clocks with the requisite combination of size, performance and environmental insensitivity for operation on mobile platforms. The 35 l clock combines a molecular iodine spectrometer, fibre frequency comb and control electronics. Three of these clocks operated continuously aboard a naval ship in the Pacific Ocean for 20 days while accruing timing errors below 300 ps per day. The clocks have comparable performance to active hydrogen masers in one-tenth the volume. Operating high-performance clocks at sea has been historically challenging and continues to be critical for navigation. This demonstration marks a significant technological advancement that heralds the arrival of future optical timekeeping networks.

部署的光学时钟将改善导航自主定位^{1 ，为地球物理监测2}和分布式相干传感³提供远程时间标准，允许远程量子网络^4,5的时间同步，并为国家时间标准提供操作冗余。尽管实验室光学时钟现在的误差分数低于 10 ^-18（参考文献^6,7），但这些高性能时钟的便携式版本^{8,9由于其尺寸、环境敏感性和成本10}，其实用性有限。在这里，我们报告了光学时钟的开发，该光学时钟具有在移动平台上运行所需的尺寸、性能和环境不敏感性的组合。 35 升时钟结合了分子碘光谱仪、光纤频率梳和控制电子设备。其中三个时钟在太平洋的一艘军舰上连续运行 20 天，每天的计时误差低于 300 皮秒。这些时钟的性能可与活性氢脉泽相媲美，但体积仅为其十分之一。在海上操作高性能时钟历来具有挑战性，并且对于导航仍然至关重要。此次演示标志着一项重大技术进步，预示着未来光学计时网络的到来。