Observation of Coulomb focusing in tunnelling ionization of noble gases
Bibliographic record
Abstract
We ionized He, Ne and Ar in the tunnelling regime with a linearly polarized laser pulse and measured the ion-recoil momentum distribution on an axis perpendicular to laser polarization for two different wavelengths (λ = 800 nm and λ = 1800 nm). We observed a significantly narrower distribution for 800 nm than for 1800 nm. Classical simulations of the electron wave packet's evolution under the combined influence of the ion's Coulomb potential and the laser field show that the narrowing is caused by Coulomb focusing of the electron wave packet during recollisions. The narrowing is sensitive on the longitudinal momentum of the wave packet after tunnelling, which suggests a way of measuring it. Measurements at 800 nm in circular polarization–for which no recollision occurs–do not exhibit this narrowing of the perpendicular momentum distribution. Simulations for circular polarization show another aspect of Coulomb focusing: the Coulomb potential also affects the wave packet's transverse momentum as it leaves the saddle point immediately after tunnelling.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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 source (direct Gemma or distilled Codex), 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".