Experimental realization of an optical second with strontium lattice clocks
Open accessAbstract
Progress in realizing the SI second had multiple technological impacts and enabled further constraint of theoretical models in fundamental physics. Caesium microwave fountains, realizing best the second according to its current definition with a relative uncertainty of 2-4 × 10(-16), have already been overtaken by atomic clocks referenced to an optical transition, which are both more stable and more accurate. Here we present an important step in the direction of a possible new definition of the second. Our system of five clocks connects with an unprecedented consistency the optical and the microwave worlds. For the first time, two state-of-the-art strontium optical lattice clocks are proven to agree within their accuracy budget, with a total uncertainty of 1.5 × 10(-16). Their comparison with three independent caesium fountains shows a degree of accuracy now only limited by the best realizations of the microwave-defined second, at the level of 3.1 × 10(-16).
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The systematic and statistical uncertainties of the two Sr lattice clocks are highly independent and uncorrelated because their implementations of state preparation and interrogation are quite different.
“The details of the actual implementation of state preparation and interrogation being quite different in the two experimental realizations of a Sr lattice clock5212223, systematic and statistical uncertainties are highly independent and uncorrelated.”
From A clock network for geodesy and fundamental science (2016) · cites this paper as [5]
The OLC architecture section says the two Sr clocks differ in key features, and the Figure 3 caption treats their combined systematic uncertainty as that of two uncorrelated clocks. Figure 1 describes independent probe feedback, but the paper does not establish that state preparation and interrogation are quite different or explicitly say that the clocks’ statistical uncertainties are uncorrelated. (LLM, conf=0.82)
Experimental — accuracy not yet measuredThe accuracy of comparing remote optical clocks using microwave signals is limited by caesium microwave clocks, with the most stringent bound set by our groups at an agreement within 4 × 10−16.
“The accuracy of the former method is limited by the caesium microwave clocks with the most stringent bound set by our groups5212223 at an agreement within 4 × 10−16”
From A clock network for geodesy and fundamental science (2016) · cites this paper as [5]
The Abstract and Discussion say that optical-to-microwave comparisons are limited by caesium-fountain accuracy; the reported uncertainty is 3.1 × 10−16, which is within 4 × 10−16. The paper compares two strontium clocks with three caesium fountains, but does not establish an agreement within 4 × 10−16 between remote optical clocks using microwave signals. No page number is available in our copy. (LLM, conf=0.86)
Experimental — accuracy not yet measuredThe international all-optical clock measurement surpasses the accuracy of the best possible comparison achievable by measurements against primary caesium clocks by one order of magnitude.
“This international all-optical clock measurement surpasses the accuracy of the best possible comparison achievable by measurements against primary caesium clocks by one order of magnitude5212223.”
From A clock network for geodesy and fundamental science (2016) · cites this paper as [5]
The Discussion (page unavailable) reports that a direct comparison of two strontium optical clocks achieved agreement better than three of the best caesium fountains could resolve. But the reported optical comparison uncertainty was 1.5 × 10⁻¹⁶ versus 3.1 × 10⁻¹⁶ for the caesium-based comparison—not an order of magnitude—and the Discussion describes comparisons between clocks at different institutes as future work, not this measurement. (LLM, conf=0.88)
Experimental — accuracy not yet measuredThis allows investigating time-dependent (for example, diurnally varying) clock data, opening up completely new research capabilities.
“This allows investigating time-dependent (for example, diurnally varying) clock data, opening up completely new research capabilities51315.”
From A clock network for geodesy and fundamental science (2016) · cites this paper as [5]
The section on comparisons with primary frequency standards describes measurements over six months used to investigate time-dependent changes in the Sr/Cs frequency ratio, including a possible yearly variation. The Discussion describes new prospects for fundamental physics, but the paper does not establish the claim’s diurnally varying example. (LLM, conf=0.85)
Experimental — accuracy not yet measured
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References 54 · Cited by 250
Research works printed but not linked: 1
- Chou, C. W., Hume, D. B., Koelemeij, J. C. J., Wineland, D. J. & Rosenband, T. Frequency comparison of two high-accuracy Al þ optical clocks. Phys. Rev. Lett. 104, 070802 (2010).
- Authors
- Le Targat, R., Lorini, L., Le Coq, Y., Zawada, M., Guéna, J., Abgrall, M., Gurov, M., Rosenbusch, P., Rovera, D. G., Nagórny, B., Gartman, R., Westergaard, P. G., Tobar, M. E., Lours, M., Santarelli, G., Clairon, A., Bize, S., Laurent, P., Lemonde, P., & Lodewyck, J.
- Affiliations
- Centre National de la Recherche Scientifique (FR)
- The University of Western Australia (AU)
- Corresponding author
- Lodewyck, J.
- ORCID
- Venue
- Nature Communications
- Published
- 2013-07-09
- Volume
- 4
- Issue
- 1
- Pages
- 2109-2109
- ISSN
- 2041-1723 (ISSN-L)
- OpenAlex
- W2011144370
- Cited by
- 250
- References
- 54
- Citations by year
- 2025: 15 · 2024: 11 · 2023: 12 · 2022: 9 · 2021: 14 · 2020: 13 · 2019: 24 · 2018: 23 · 2017: 23 · 2016: 28 · 2015: 39 · 2014: 29 · 2013: 10
- FWCI
- 18.19
- Type
- journal article
- Language
- en
- Update notices
- correction (2013-10-31)
- Open access
- bronze
- doi.org
- Licence
- Locations
- Nature Communications (publishedVersion)
- PubMed (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- UWA Profiles and Research Repository (UWA) (submittedVersion)
- HAL (submittedVersion, cc-by)
- RePEc: Research Papers in Economics (submittedVersion)
- CINECA IRIS Institutional Research Information System (IRIS Istituto Nazionale di Ricerca Metrologica) (submittedVersion)
- arXiv (Cornell University)
- Funders
- Centre National d’Etudes Spatiales
- Centre National de la Recherche Scientifique
- Institut Francilien de Recherche sur les Atomes Froids
- Topics
- Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Advanced Frequency and Time Standards
- Physical Sciences › Computer Science › Computer Networks and Communications › Network Time Synchronization Technologies
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Scientific Measurement and Uncertainty Evaluation
- Keywords
- strontium optical lattice clock, clock comparison, optical frequency standard, microwave frequency standard, frequency metrology
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