Quantum-limited optical time transfer for future geosynchronous links

Caldwell, Emily D.; Deschênes, Jean-Daniel; Ellis, Jennifer L.; Swann, William C.; Stuhl, Benjamin; Bergeron, Hugo; Newbury, Nathan R.; Sinclair, Laura C.

doi:10.1038/s41586-023-06032-5

Cited by 21 publications

(7 citation statements)

References 45 publications

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“…There is no systematic frequency shift reported so far in the range of 10 −16 [83]. Modulation of the optical carrier frequency enables a frequency reference in the radio and microwave domain (10 MHz−10 GHz) to be transmitted, with typical uncertainty less than 10 −17 at 10 4 s. Latest synchronization experiments report 300 km free space link and demonstrate a sub ps capability [84].…”

Section: Tf Transfermentioning

confidence: 99%

Roadmap towards the redefinition of the second

Dimarcq,

Gertsvolf,

Mileti

et al. 2024

Metrologia

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This paper outlines the roadmap towards the redefinition of the second, which was recently updated by the CCTF Task Force created by the CCTF in 2020. The main achievements of optical frequency standards (OFS) call for reflection on the redefinition of the second, but open new challenges related to the performance of the optical frequency standards, their contribution to time scales and UTC, the possibility of their comparison, and the knowledge of the Earth’s gravitational potential to ensure a robust and accurate capacity to realize a new definition at the level of 10-18 uncertainty. The mandatory criteria to be achieved before redefinition have been defined and their current fulfilment level is estimated showing the fields that still needed improvement. The possibility to base the redefinition on a single or on a set of transitions has also been evaluated. The roadmap indicates the steps to be followed in the next years to be ready for a sound and successful redefinition.

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Section: Tf Transfermentioning

confidence: 99%

Roadmap towards the redefinition of the second

Dimarcq,

Gertsvolf,

Mileti

et al. 2024

Metrologia

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“…In 2023, Caldwell et al demonstrated two-way time-frequency transfer based on optical frequency combs over a 300 km free-space link, and the link loss supported 102 dB. Meanwhile, different sites were synchronized to 320 attosecond [100].…”

Section: Free-space Time-frequency Transfermentioning

confidence: 99%

“…In 2011, Quinlan et al demonstrated an Er-doped fiber comb system with a repetition rate of 200 MHz, which was locked to an ultra-stable optical reference source. The fiber comb system produced a low-noise 10 GHz signal accompanied by phase noise of less than −100 dBc/Hz at a 1Hz offset [100]. The performance of low-noise microwaves can be also evaluated by a photonic delay line [102,103].…”

Section: Low-noise Microwave Generationmentioning

confidence: 99%

Recent Advances, Applications, and Perspectives in Erbium-Doped Fiber Combs

Yan,

Xu,

et al. 2024

Photonics

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Optical frequency combs have emerged as a new generation of metrological tools, driving advancements in various fields such as free-space two-way time–frequency transfer, low-noise microwave source generation, and gas molecule detection. Among them, fiber combs based on erbium-doped fiber mode-locked lasers have garnered significant attention due to their numerous advantages, including low noise, high system integration, and cost-effectiveness. In this review, we discuss recent developments in erbium-doped fiber combs and analyze the advantages and disadvantages of constructing fiber combs utilizing different erbium-doped mode-locked fiber lasers. First, we provide a brief introduction to the basic principles of optical frequency combs. Then, we explore erbium-doped fiber combs implemented utilizing various mode-locking techniques, such as nonlinear polarization rotation (NPR), real saturable absorber (SA), and nonlinear amplifying loop mirror (NALM). Finally, we present an outlook on the future perspectives of erbium-doped fiber combs.

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“…The Global Navigation Satellite System is a network of distributed, high-performance microwave-based atomic clocks that provide nanosecond-level synchronization globally. The emergence of fieldable optical timekeeping, which offers femtosecond timing jitter at short timescales and multiday, subnanosecond holdover, along with long-distance femtosecond-level optical time transfer 12 , paves the way for global synchronization at picosecond levels.…”

Section: Mainmentioning

confidence: 99%

Optical clocks at sea

Roslund,

Cingöz,

Lunden

et al. 2024

Nature

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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 networks4,5 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 clocks8,9 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.

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Quantum-limited optical time transfer for future geosynchronous links

Cited by 21 publications

References 45 publications

Roadmap towards the redefinition of the second

Roadmap towards the redefinition of the second

Recent Advances, Applications, and Perspectives in Erbium-Doped Fiber Combs

Optical clocks at sea

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