Absolute frequency measurement of a ⁸⁸Sr⁺ clock by direct comparison to a primary frequency standard

Download	View final version: Absolute frequency measurement of a ⁸⁸Sr⁺ clock by direct comparison to a primary frequency standard (PDF, 3.0 MiB)
DOI	Resolve DOI: https://doi.org/10.1088/1681-7575/ade4d1
Author	Search for: Marceau, Claude¹ORCID identifier: https://orcid.org/0000-0002-8167-2727; Search for: Beattie, Scott¹ORCID identifier: https://orcid.org/0000-0003-2056-2871; Search for: Kato, Kosuke¹ORCID identifier: https://orcid.org/0000-0001-9292-2931; Search for: Jian, Bin¹ORCID identifier: https://orcid.org/0000-0002-4588-3957; Search for: Gertsvolf, Marina²ORCID identifier: https://orcid.org/0000-0002-1188-2104; Search for: Dubé, Pierre¹ORCID identifier: https://orcid.org/0000-0003-0133-2165
Affiliation	National Research Council Canada. Metrology Research Centre National Research Council Canada. Quantum and Nanotechnologies
Format	Text, Article
Subject	absolute frequency measurement; optical atomic clock; strontium ion clock; cesium fountain clock; GNSS frequency transfer; TAI
Abstract	We report on a measurement of the absolute frequency of the ⁸⁸Sr⁺ clock transition via a direct comparison to our cesium fountain clock, National Research Council Canada (NRC)-FCs2. The measurement yield a value of 444779044095485.404±0.045 Hz. The corresponding fractional uncertainty of 1.0 × 10⁻¹⁶ is, to our knowledge, the lowest so far reported for an absolute frequency measurement. The low uncertainty obtained is primarily a consequence of improvements to NRC-FCs2, specifically a systematic uncertainty of 9.3 × 10⁻¹⁷ and a stability of 6.3 × 10⁻¹⁴/√τ . The measurement was made over a period of 37 days with 68% uptime, for a total measurement time of 2.16 × 10⁶ s. The ⁸⁸Sr⁺ frequency was also compared to terrestrial time via a global navigation satellite system (GNSS) link to Universal Coordinated Time, yielding a frequency value of 444 779044095485.406±0.089 Hz, which is in agreement with the direct comparison with NRC-FCs2.
Publication date	2025-06-25
Publisher	IOP Publishing
Copyright statement	© 2025 The Author(s). Published on behalf of BIPM by IOP Publishing Ltd
Licence	Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/
In	Metrologia 62, no. 4, 045001 (25 June 2025): 1–8.
Language	English
Peer reviewed	Yes
Export citation	Export as RIS
Report a correction	Report a correction (opens in a new tab)
Record identifier	5dd29108-050f-447b-9cb0-9c6962f52aca
Record created	2026-03-23
Record modified	2026-04-21

Page details

From:

National Research Council Canada

Date modified:: 2026-04-24