Quantum lifetime in ultrahigh quality GaAs quantum wells: Relationship to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Δ</mml:mi><mml:mrow><mml:mn>5</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math> and impact of density fluctuations
Bibliographic record
Abstract
We consider the quantum lifetime derived from low-field Shubnikov--de Haas oscillations as a metric of the quality of the two-dimensional electron gas in GaAs quantum wells that expresses large excitation gaps of the $\ensuremath{\nu}=\frac{5}{2}$ fractional quantum Hall state in the $N=1$ Landau level. In high quality samples, small density inhomogeneities dramatically impact the amplitude of Shubnikov--de Haas oscillations such that the canonical method [cf. Coleridge, Phys. Rev. B 44, 3793 (1991)] for determination of the quantum lifetime substantially underestimates ${\ensuremath{\tau}}_{\text{q}}$ unless density inhomogeneity is explicitly considered. We have developed a method that can be used to determine density inhomogeneity and extract the intrinsic ${\ensuremath{\tau}}_{\text{q}}$ by analyzing the Shubnikov--de Haas oscillations. However, even after accounting for inhomogeneity, ${\ensuremath{\tau}}_{\text{q}}$ does not correlate well with sample quality as measured by ${\mathrm{\ensuremath{\Delta}}}_{5/2}$, the excitation gap of the fractional quantum Hall state at 5/2 filling.
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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 | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.029 | 0.003 |
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; both teacher heads agree on what is shown here.
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".