| Project/Area Number |
03452048
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
SATOH Takeo 東北大学, 理学部, 助教授 (00004424)
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| Co-Investigator(Kenkyū-buntansha) |
TAKIGAWA Noboru 東北大学, 理学部, 助教授 (00125600)
TAKAGI Shin 東北大学, 理学部, 助教授 (90124594)
YAMAGUCHI Akira 東北大学, 理学部, 助教授 (60004470)
SAWADA Anju 東北大学, 理学部, 助教授 (90115577)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1992: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1991: ¥5,700,000 (Direct Cost: ¥5,700,000)
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| Keywords | First Order Phase Transition / Decomposition / Quantum Tunneling / Macroscopic Quantum Phenomena / ^3He-^4He Liquid Mixtures / Ultralow Temperature / Superfluidity / Quantum Nucleation / ^3He-^4He混合液 / 量子揺らぎ / 巨視的量子効果 / ^3Heー^4He混合液 |
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| Research Abstract |
A first order phase transition is the change of state from a metastable to a stable phase as the result of fluctuation in a homogeneous metastable medium, nuclei. For the nucleation, there is a potential barrier due to the creation of an interface. Usually, the fluctuation is the thermal fluctuation. However, in a temperature region extremely low compared with barrier height, the thermal fluctuation is no longer effective. If we still have any first order phase transition in such a situation, the nucleation must be due to the quantum tunneling. Quantum nucleation is a kind of macroscopic quantum phenomenon.
In order to investigate the possibility of the quantum nucleation, the decomposition of supersaturated ^3He-^4He liquid mixtures in the dilute phase has been studied in the temperature range from 160 mK down to 400 muK. The observed amount of critical supersaturation becomes almost independent of temperature below about 10 mK, while it increases above about 10 mK. The temperature- independent behavior suggests that we are in the quantum regime at least below about 10 mK. The behavior above about 10 mK conflicts with a simple expectation of the crossover consideration from the quantum to the classical regime. This fact suggests the importance of the effect of dissipation in macroscopic quantum phenomenon.
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