| 研究課題/領域番号 |
22K14560
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| 研究機関 | 京都大学 |
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研究代表者 |
ヘルブスレブ デイヴィト 京都大学, 化学研究所, 特定助教 (40817904)
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| 研究期間 (年度) |
2022-04-01 – 2024-03-31
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| キーワード | NV centre / Dopant / Phosphorus / Quantum sensing |
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| 研究実績の概要 |
In order to investigate the key scientific question, "can the electron spins of phosphorus donors nearby NV centres in diamond be used as quantum sensors", at first a couple of phosphorus doped samples were measured. The doping concentrations were about 10^16 atoms/cm^3. However, as opposed to the initial measurements, there was no response from any defects/impurities nearby the measured NV centres. There are several potential explanations for this, which are researched currently. The first, a higher phosphorus concentration might be needed to have a fair chance to have a donor close enough to the NV centre. This will be tried by increasing the phosphorus concentration as much as possible. Secondly, the measurement method might be insufficient. To study this, we decided to look at a more "straightforward" (yet new) situation: coupling two NV centres. With the help of QST, we implanted molecules with multiple nitrogen atoms into phosphorus-doped diamond to have a high chance to have NV centres close together. The idea was to first try to use such couples for quantum sensing, as interaction with both NV centres is possible (if their orientation is different), hence it is easier compared to using dark spins. Although we were able to find couples of NV centers with different orientations fairly easily, they were either not stable (probably charge state), or their coherence times were very short (about a microsecond instead of close to a millisecond). Thirdly, we looked at a different measurement method that might be more suitable. The latter we will submit for publication soon.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
4: 遅れている
理由
Currently, no connection between the dopants and the NV centre has been established. Although this is the central topic of the research, if it turns out that it is rather hard, the backup results we got from this research are rather interesting by themselves. We have in-depth analysed entanglement (one of the envisioned, though more advanced, ways to sense with a combination of spins) for use with NV centres, which debunks the often stated potential improvement of 1/N (with N NV centres/spins), but shows that it could be 1/N^(3/4). This likely fuels a different project, as entanglement is an important step forward. Secondly, we devised a new sensing method, which we call std (standard deviation) sensing, which should help in our current project, but it also has high potential for different sensors in particle physics applications.
Nonetheless, it would be great if we can establish a connection, any at all, between the phosphorus dopant and the NV centre, and potentially compare it with the NV centre couples to see which one has the most potential moving forward.
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| 今後の研究の推進方策 |
The future plan is to use a more highly phosphorus doped diamond sample expecting to increase the chances to have a donor close enough to a NV centre. We started with more lowly doped samples, as these have longer coherence times based on our earlier research. To couple them would be a mayor result at this point. The experiment with the two coupled NV centres does suggest that maybe the coherence time will be strongly affected, such that there is no (clear) advantage even if they are coupled (compared to using a single NV centre only). However, it would still be the goal to at least show this coupling, and the effect, whether good or bad.
Moreover, some new hardware arrived (a more advanced counter, in our case used to count photons that determine the spin state), which should allow for longer experiments, lowering the noise. Thus, if any coupling is already there, but due to the noise it is hard to distinguish it, adding the new hardware to the experimental setup will improve the chances to discover the coupling between the NV centre and nearby defects.
Finally, we are writing up the draft for the novel std sensing method.
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