{"paper":{"title":"Absolute frequency measurement of the $^2$S$_{1/2} \\rightarrow ^2$F$_{7/2}$ optical clock transition in $^{171}$Yb$^+$ with an uncertainty of $4\\times 10^{-16}$ using a frequency link to International Atomic Time","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"physics.atom-ph","authors_text":"Antoine Rolland, Charles F. A. Baynham, Fred Baynes, Helen S. Margolis, Jonathan M. Jones, Kai Bongs, Patrick E. G. Baird, Patrick Gill, Peter B. R. Nisbet-Jones, Rachel M. Godun, Steven A. King","submitted_at":"2017-07-03T16:52:37Z","abstract_excerpt":"The highly forbidden $^2$S$_{1/2} \\rightarrow ^2$F$_{7/2}$ electric octupole transition in $^{171}$Yb$^+$ is a potential candidate for a redefinition of the SI second. We present a measurement of the absolute frequency of this optical transition, performed using a frequency link to International Atomic Time to provide traceability to the SI second. The $^{171}$Yb$^+$ optical frequency standard was operated for 76% of a 25-day period, with the absolute frequency measured to be 642 121 496 772 645.14(26) Hz. The fractional uncertainty of $4.0 \\times 10 ^{-16}$ is comparable to that of the best p"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1707.00646","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}