<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Sr</mml:mi><mml:none/><mml:mo>+</mml:mo><mml:mprescripts/><mml:none/><mml:mn>88</mml:mn></mml:mmultiscripts></mml:math>445-THz Single-Ion Reference at the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>17</mml:mn></mml:mrow></mml:msup></mml:math>Level via Control and Cancellation of Systematic Uncertainties and Its Measurement against the SI Second
Why this work is in the frame
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Bibliographic record
Abstract
We describe experiments and measurements on a trapped and laser-cooled single ion of $^{88}\mathrm{Sr}^{+}$ which, when probed on its reference $5s\text{ }^{2}S_{1/2}\ensuremath{\rightarrow}4d\text{ }^{2}D_{5/2}$ transition at 445 THz, provides an optical frequency standard of evaluated accuracy outperforming the current realization of the SI second. Studies are presented showing that micromotion-associated shifts of the standard can be reduced to the ${10}^{\ensuremath{-}18}$ level and uncertainties in the blackbody-induced shifts for the current system are at the low ${10}^{\ensuremath{-}17}$ level due to the relatively well-known polarizability of the strontium ion system and careful choice of the trap structure. The current evaluated systematic shifts for the ion transition are at a fractional uncertainty of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$. An absolute frequency measurement performed over a two-month period relative to a maser referenced to the SI second via Global Positioning System time transfer has determined the center frequency for the transition at ${\ensuremath{\nu}}_{SD}=444\text{ }779\text{ }044\text{ }095\text{ }485.5\ifmmode\pm\else\textpm\fi{}0.9\text{ }\text{ }\mathrm{Hz}$ ($1\ensuremath{\sigma}$).
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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 | 0.004 | 0.002 |
| Meta-epidemiology (narrow) | 0.003 | 0.004 |
| Meta-epidemiology (broad) | 0.002 | 0.004 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.004 | 0.004 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.004 | 0.003 |
| Research integrity | 0.002 | 0.004 |
| Insufficient payload (model declined to judge) | 0.008 | 0.002 |
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 it