| Project/Area Number |
17540294
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
TAKAGAHARA Toshihide Kyoto Institute of Technology, Graduate School of Science and Technology, Professor, 工芸科学研究科, 教授 (00111469)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | electron spin / quantum dot / decoherence / electron-phonon interaction / nuclear spin / hyperfine interaction / 半導体量子ドット / スピン位相緩和 / 量子状態制御 / スピンコヒーレンス / 結合量子ドット |
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| Research Abstract |
We investigated theoretically the electron spin relaxation rate in a single quantum disk and clarified its dependence on the magnetic field strength, the temperature and the strength of quantum confinement. In the weak confinement regime, the spin relaxation rate at low temperatures is dominated by the two-phonon processes and its dependence on the magnetic field is rather weak. In the strong confinement regime, on the other hand, the spin relaxation rate at low temperatures is governed by the one・phonon processes and exhibits the characteristic fourth power dependence on the magnetic field at moderately strong field range. However, it is predicted that a crossover occurs in the relative weight between the one・phonon and the two-phonon processes around a few Tesla and the spin relaxation rate at low magnetic fields is determined by the two・phonon processes.
We have investigated the quantum dynamics of the electron・nuclei coupled system in a double quantum dot and discovered a couple of new phenomena related to the quantum nature of nuclear spin system. Especially, the bunching of results of the electron spin measurements and the revival in the conditional probabilities are salient features of quantum dynamics. The underlying mechanism is the squeezing of the nuclear spin state through the electron spin measurements. This squeezing is expected to lead to the elongation of the electron spin coherence time.
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