Nucleation in Supersaturated ^3He-^4He Liquid Mixtures - Quantum Effects in First Order Phase Transition -

过饱和 ^3He-^4He 液体混合物中的成核 - 一阶相变中的量子效应 -

• 批准号: 03452048
• 负责人: SATOH Takeo
• 金额: $ 4.22万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452048/
• 关键词: 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

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.

一阶相变是由于均匀的亚稳介质（原子核）的波动而导致的从亚稳态到稳定相的状态变化。对于成核，由于界面的形成，存在一个势垒。通常，波动是热波动。然而，在与势垒高度相比极低的温度区域，热波动不再有效。如果在这种情况下我们仍然有任何一阶相变，那么成核一定是由于量子隧穿。量子成核是一种宏观的量子现象。为了研究量子成核的可能性，在160 ~ 400 muK的温度范围内，研究了过饱和^3He-^4He液体混合物在稀相中的分解。观察到的临界过饱和量在约10 mK以下几乎与温度无关，而在约10 mK以上则增加。与温度无关的行为表明我们至少处于约10 mK以下的量子状态。高于约10 mK的行为与从量子到经典状态的交叉考虑的简单期望相冲突。这一事实说明了耗散效应在宏观量子现象中的重要性。

项目成果

A.B.Balantekin,J.R.Bennett,N.Takigawa and Y.Alhassid: "Two-time Influence Functional Approach to Multidimensional Quantum Tunneling" Proceedings of the 4th International Symposium on Foundation of Quantum Mechanics. (1993)

A.B.Balantekin、J.R.Bennett、N.Takikawa 和 Y.Alhassid：“多维量子隧道的两次影响函数方法”第四届量子力学基础国际研讨会论文集。

T.Satoh, M.Morishita, M.Ogata, A.Sawada and T.Kuroda: "Unsaturation, Supersaturation and Demixing in ^3He-^4He Mixtures" Physica B. 169. 513-514 (1991)

T.Satoh、M.Morishita、M.Ogata、A.Sawada 和 T.Kuroda：“^3He-^4He 混合物中的不饱和、过饱和和分层” Physica B. 169. 513-514 (1991)

N.Takigawa: "Fusion of a Halo Nucleus and Synthesis of Superheavy Elements" Nuclear Physics A. 538. 221C-228C (1992)

N.Takikawa：“晕核的聚变与超重元素的合成”核物理 A. 538. 221C-228C (1992)

W.Itoh: "New Silver Powders with Large Surface Area as Heart Exchanger Materials" Cryogenics. 31. 453-455 (1991)

W.Itoh：“具有大表面积的新型银粉作为心脏交换器材料”Cryogenics。

T.Tsuda,Y.Mori and T.Satoh: "Superleak-tight Cold Valve Testable at Room Temperature" Review of Scientific Instrument. 62. 841 (1991)

T.Tsuda、Y.Mori 和 T.Satoh：“可在室温下测试的超级防漏冷阀”科学仪器评论。