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arXiv:2406.03716 · Nature Communications

Demonstration of a mobile optical clock ensemble at sea

A. P. Hilton, Rachel F. Offer, Elizaveta Klantsataya, S. K. Scholten, Sarah K. Scholten, Christopher J. Billington, Clayton R. Locke, Christopher Perrella, Montana Nelligan, J. W. Allison, B. White, E. Ahern, Kyle W. Martin, R. Beard, John Elgin, Ben M. Sparkes, Andre Nicholas Luiten

Published Jul 2, 2025• 22 citations

Abstract

Atomic clocks are at the leading edge of accuracy and precision and are essential for synchronisation of distributed critical infrastructure, position, navigation and timing, and scientific applications. There has been significant improvements in the performance of atomic clocks with the shift from microwave to optical frequency transitions. However, this performance increase has come at the cost of size, complexity and fragility, which has confined optical clocks to laboratories. Here we report on a recent international collaboration where three emerging optical clocks, each based on different operating principles, were trialled at sea. These clocks demonstrated world-class performance and reliability by providing stable frequency outputs in optical, microwave and radio-frequency domains over three weeks of unsupervised naval operation. Atomic clocks using optical transitions have much better frequency stability compared to microwave counterparts, but are also more complex, which means their use has been mostly lab-based so far. Here, the authors demonstrate successful operation of three different optical atomic clocks on a ship at sea for three weeks.

DOI: 10.1038/s41467-025-61140-2

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Optical frequency standards surpass their microwave counterparts in both stability and accuracy, yet they are often bulky, power-hungry, and unable to operate outside of a well-controlled laboratory environment. Leveraging a two-photon transition in

{}^{87}

Rb vapor and recent advances in fiber frequency combs, the authors build an optical clock to beat the current portable standards, with an architecture that can be made compact and low-power. These results point the way to a real-world optical frequency standard of even higher stability, for applications such as satellite navigation.

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