BACON optical ratios · Precision and disagreement
Research context
development · conditional · As of 2026-10-10
preprint · 2026-07-16
- Study design
- Pairwise optical-clock frequency comparisons with repeated systematic-shift evaluations and link/ratio uncertainty accounting.
- Reported result
- Reports ratios with total fractional uncertainty ≤3.2×10⁻¹⁸ and disagreements with earlier ratio measurements.
- Limitations
- Preprint and instrument-specific error budget; precision claims must be tested by independent repeated comparisons and current standards governance.
Aeppli and collaborators' archived 2025/2026 report compares 27Al⁺, 171Yb and 87Sr optical clocks with reported total fractional ratio uncertainties at or below 3.2×10⁻¹⁸.
Key knowledge
Aeppli and collaborators' archived 2025/2026 report compares 27Al⁺, 171Yb and 87Sr optical clocks with reported total fractional ratio uncertainties at or below 3.2×10⁻¹⁸. Differences from earlier measurements were larger than some earlier uncertainty budgets. The comparison motivates repeated independent interlaboratory checks; meeting a precision milestone is not itself adoption of a new SI definition.
Conditions and scope
- The inspected arXiv report is a preprint; NIST's 10 April 2026 publication page is an official posting, not separate independent replication.
- The quoted bound is on the reported ratios, not every clock/environment or every link. Repeated systematic evaluations and unaccounted effects govern interpretation.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
National Institute of Standards and Technology (NIST)2 sources
- Atomic clock frequency ratios with fractional uncertainty ≤3.2×10⁻¹⁸Alexander Aeppli and BACON/NIST/JILA collaboratorsResearch paper
- Statistical methods for next-generation clock networks (2025 project update)NIST Statistical Engineering Division and optical-clock collaboratorsResearch project overview
- Redefinition of the second · Current roadmap FAQBIPM / CCTF task forceReference guide
Evidence and review
Inspected v2 submitted 16 July 2026: abstract, measurement model, results, discrepancy discussion and systematic checks; initial preprint24 December 2025 and NIST2026 posting are separate dates; source check dated 2026-10-10. Scope is limited to the cited statements, equations and assumptions, not the whole publication. Inspected between-day excess scatter and hierarchical ratio-model account; project summary, not original experimental full text; source check dated 2026-10-10. Scope is limited to the cited statements, equations and assumptions, not the whole publication. Inspected 2030 conditional decision milestone and alternative definition options; reviewed 2026-10-10; source check dated 2026-10-10. Scope is limited to the cited statements, equations and assumptions, not the whole publication.
2026-10-10 · Author source inspection of the displayed claim, model assumptions and equations; independent exact-content and branch-inventory review is a separate gate. Contemporary status is a dated snapshot, not a promise of ongoing monitoring.
Entry details
Permanent link to this entry ↗- Record identity
- research-measurement-clock-ratios-current
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference