All-optical coherent control of electrical currents in centrosymmetric semiconductors
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Bibliographic record
Abstract
The absorption of phase-related near-infrared fundamental $(\ensuremath{\omega},0.7\phantom{\rule{0.3em}{0ex}}\mathrm{eV}\ensuremath{\leqslant}\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\leqslant}0.9\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ and second harmonic $(2\ensuremath{\omega})$ pulses of $150\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ duration results in ballistic electrical currents in clean bulk germanium and silicon at room temperature. The ultrafast charge motion is directly monitored via a time-resolved analysis of the emitted bursts of terahertz radiation. The current generation process relies on a third-order optical nonlinearity with a current injection efficiency only slightly reduced compared to the established current injection in direct-gap semiconductors such as GaAs. In the present case, current injection takes place across the direct band gap of germanium, whereas it involves indirect optical transitions in silicon. The vector direction of the current is defined by the polarization of the two-color pump field and the relative phase $\ensuremath{\Delta}\ensuremath{\Phi}=2{\ensuremath{\Phi}}_{\ensuremath{\omega}}\ensuremath{-}{\ensuremath{\Phi}}_{2\ensuremath{\omega}}$. Microscopically, current injection can be understood as arising from the quantum interference of one- and two-photon absorption processes. In the case of silicon, these indirect optical transitions may involve different types of phonons and can occur via numerous pathways. We therefore propose a model based on third-order perturbation theory which qualitatively explains why a current injection can occur across an indirect band gap.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it