Absolute Frequency Measurement of the Sr<sup>+</sup> Ion Optical Clock With a Fourfold Uncertainty Reduction
Bibliographic record
Abstract
SummaryWe have made an absolute frequency measurement of the electric quadrupole clock transition of the <sup>88</sup>Sr<sup>+</sup> ion in June 2017, using a satellite link to the SI second. The measurement uptime was 92 h. The uncertainty of the measurement has been reduced by a factor of four compared to our previous best measurement that had an uptime of 100 h. The lower uncertainty of the measurement reported here is the result of an improved evaluation of the link uncertainties and of a better use of the high stability of the maser flywheel oscillator. The favorable maser noise properties allows the extension of the maser evaluation period over the full 30 days of the Circular T report of June 2017 without significant degradation of the dead time uncertainty between the maser and the optical clock. Avenues to improve future absolute frequency measurements are also discussed.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".