An experimental study of single hole spin qubit coherence in a GaAs/AlGaAs double quantum dot device
Bibliographic record
Abstract
This thesis discusses a series of experiments performed on a p-type laterally-gated GaAs/AlGaAs double quantum dot device. The main purpose of these experiments was to explore the potential of a theoretically-predicted increase in the spin coherence time T_2^* for the usage of a single hole pseudo-spin in GaAs, as opposed to a conduction-band electron. \n\tThe “Introduction” section provides a brief overview of the history of the Loss-DiVincenzo spin qubit and the motivation to iterate upon its implementations in light of the DiVincenzo criteria for quantum computing. It also places the experiments in this thesis in context with regard to preceding experiments of a similar nature performed in the same research group. \n\tThe “Relevant Background Information” section provides an exploration of a number of topics that aid the non-expert in familiarizing themselves with the principles of semiconductor quantum dots, understanding the functionality of the device and methods used, and interpreting the results of the experiments. \n\tThe “Readout” section explains the process by which the single-shot experiments and spin-to-charge readout scheme are prepared, performed, and detected by room-temperature electronics. The process by which the various tunneling times of the system are tuned in order for the pulsing scheme to function is then discussed. Finally, the energy level alignments for successful hole transfer are identified experimentally. \n\tThe “Results and Discussion” section presents and describes the results of the various experiments performed in order to fully characterize the coherence characteristics of the device. Following successful spin excitation via EDSR, the state of the hole pseudo-spin was manipulated via Rabi experimentation. Methods for maximizing device performance are motivated, explained, and displayed. The coherence times T_2^* and T_2^CPMG are then determined via Ramsey, Hahn-echo, and CPMG experiments. These results are then discussed and compared to contemporaries. The spin relaxation time T_1 is extracted and compared with previous results on the same device. Finally, an additional functionality is explored in which the dot effective g-factor is tuned electrically via gate voltage pulsing within each single-shot experiment.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| 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".