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arXiv · 1509.07888

Synchronization of Distant Optical Clocks at the Femtosecond Level

Jean-Daniel Deschenes·Laura C. Sinclair·Fabrizio R. Giorgetta·William C. Swann·Esther Baumann·Hugo Bergeron·Michael Cermak·Ian Coddington·Nathan R. Newbury
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Abstract

The use of optical clocks/oscillators in future ultra-precise navigation, gravitational sensing, coherent arrays, and relativity experiments will require time comparison and synchronization over terrestrial or satellite free-space links. Here we demonstrate full unambiguous synchronization of two optical timescales across a free-space link. The time deviation between synchronized timescales is below 1 fs over durations from 0.1 s to 6500 s, despite atmospheric turbulence and kilometer-scale path length variations. Over several days, the time wander is 40 fs peak-to-peak. Our approach relies on the two-way reciprocity of a single-spatial-mode optical link, valid to below 225 attoseconds across a turbulent 4-km path. This femtosecond level of time-frequency transfer should enable optical networks using state-of-the-art optical clocks/oscillators.

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Jean-Daniel Deschenes, Laura C. Sinclair, Fabrizio R. Giorgetta, William C. Swann, Esther Baumann, Hugo Bergeron, Michael Cermak, Ian Coddington, Nathan R. Newbury. 2015-09-25. Synchronization of Distant Optical Clocks at the Femtosecond Level. https://doi.org/10.1103/physrevx.6.021016

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