Sensitive detection of terahertz pulses via parametrically upconverted near-infrared photons
Bibliographic record
Abstract
We combine electro-optic sampling with single-photon counting technology to resolve weak terahertz (THz) radiation. A gallium-phosphide (GaP) crystal is used as the nonlinear medium for the parametric frequency conversion of broadband terahertz radiation to near-infrared (NIR) photons. The upconverted photons are measured using a monochromator combined with a single-photon counting module (SPCM). Results show good agreement of the measured upconverted photons with the theory of sum-frequency mixing [1]. We also demonstrate that our detection technique is 180 times faster than standard electro-optic sampling and can access selected spectral components of the THz field with a resolution of 170 GHz. At 2.5 THz, results show a minimum detectable THz pulse energy of $20\times 10^{-21}$ J, which corresponds to 3 photons/pulse. This THz detection technique based on a SPCM holds a strong potential for high-speed wireless THz communication systems as well as quantum sensing [2, 3].
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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 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".