Optical two-way time and frequency transfer over free space
By F. Giorgetta, William C. Swann, L. Sinclair, Esther Baumann, Ian Coddington, Nathan R. Newbury. Nature Photonics, 2012
296 citations recorded by the source corpus.
The transfer of high-quality time–frequency signals between remote locations underpins many applications, including precision navigation and timing, clock-based geodesy, long-baseline interferometry, coherent radar arrays, tests of general relativity and fundamental constants, and future redefinition of the second1,2,3,4,5,6,7. However, present microwave-based time–frequency transfer8,9,10 is inadequate for state-of-the-art optical clocks and oscillators1,11,12,13,14,15,16 that have femtosecond-level timing jitter and accuracies below 1 × 10−17. Commensurate optically based transfer methods are therefore needed. Here we demonstrate optical time–frequency transfer over free space via two-way exchange between coherent frequency combs, each phase-locked to the local optical oscillator. We achieve 1 fs timing deviation, residual instability below 1 × 10−18 at 1,000 s and systematic offsets below 4 × 10−19, despite frequent signal fading due to atmospheric turbulence or obstructions across the 2 km link. This free-space transfer can enable terrestrial links to support clock-based geodesy. Combined with satellite-based optical communications, it provides a path towards global-scale geodesy, high-accuracy time–frequency distribution and satellite-based relativity experiments. Using two-way exchange between coherent frequency combs, each phase-locked to the local optical oscillator, optical time–frequency transfer is demonstrated in free space across a 2-km-long link, with a timing deviation of 1 fs, a residual instability below 10−18 at 1,000 s and systematic offsets below 4 × 10−19.
Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering
View Paper: https://www.semanticscholar.org/paper/5a537f1597c4c2c082818aa9dc202fbde1721cd0
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In Atomic and Molecular Physics, and Optics
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Citations in the corpus
- Synchronization of Distant Optical Clocks at the Femtosecond Level (2015, unknown): “[36] over 2 km (gray trace) despite the additional complexity.”
- Micius quantum experiments in space (2022, background): “Many important works on high-precision and high-stability optical timefrequency transfers with free space and a fiber link have been reported (Smith et al., 2006; Étienne et al., 2008; Predehl et al., 2012; Giorgetta et al., 2013; Sinclair, Laura et al., 2018).”