{"paper":{"title":"Interspecies clock comparison below $5 \\times 10^{-18}$ uncertainty with a transportable clock","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["quant-ph"],"primary_cat":"physics.atom-ph","authors_text":"Chetan Vishwakarma, Christian Lisdat, Erik Benkler, Ingo Nosske, Martin Steinel, Melina Filzinger, Nils Huntemann, S\\\"oren D\\\"orscher, Tim L\\\"ucke","submitted_at":"2026-08-03T08:48:18Z","abstract_excerpt":"We report a measurement of the optical frequency ratio between the $^2\\mathrm{S}_{1/2}(F=0)$--${^2\\mathrm{F}_{7/2}(F=3)}$ electric-octupole (E3) transition of $^{171}$Yb$^{+}$ and the $^1\\mathrm{S}_0$--${^3\\mathrm{P}_0}$ transition of $^{87}$Sr, $\\nu_{\\mathrm{Yb}^{+}}/\\nu_\\mathrm{Sr} = 1.495\\,991\\,618\\,544\\,900\\,588\\,1(65)$. Reaching a fractional uncertainty of $4.3 \\times 10^{-18}$, this result improves upon the previous best by more than a factor of three and is among the few that meet the requirements for interspecies clock comparisons specified by the roadmap towards the redefinition of th"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2608.01916","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2608.01916/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}