Study of relaxation phenomena in strongly fluctuating quantum syetems

强涨落量子系统中弛豫现象的研究

• 批准号: 06640503
• 负责人: MIYASHITA Seiji
• 金额: $ 1.34万
• 依托单位: Osaka University (1995)Kyoto University (1994)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640503/
• 关键词: quantum fluctuation; metastable state; phase transition; 量子ゆらぎ; 準安定性; トンネル効果; モンテカルロ法; 核形成

We study relaxation phenomena from metastable states which appear in the ordered states below the critical points. In particular, we study the cases at very low temperatures where no thermal fluctuation are expected and the syatem is in freezing state in classical sense. Even in such cases, system still can relax through quantum fluctuations. In order to clarify mechanisms of such relazation by quantum fluctuation, we developed method to investigate dynamical property of quantum system. For example, purely quantum mechanical method (Schrodinger equation), reduced density matrix method, etc.The study includes quantum tunneling phenomena, Landau-Zener process. For quantum tunneling phenomena we proposed direct approach to the phenomana and it could give a complementary understanding of the phenomana to the field theoretical methods which are popular recently.

我们研究了亚稳态的弛豫现象，这些亚稳态出现在低于临界点的有序态中。特别地，我们研究了在非常低的温度下，没有热涨落的情况下，系统是在经典意义上的冻结状态。即使在这种情况下，系统仍然可以通过量子涨落放松。为了阐明量子涨落引起的这种相对化的机制，我们发展了研究量子系统动力学性质的方法。例如，纯量子力学方法（薛定谔方程）、约化密度矩阵方法等。研究包括量子隧道现象、朗道-齐纳过程。对于量子隧穿现象，我们提出了直接的方法，它可以给一个补充的理解现象，目前流行的场论方法。

项目成果

山本昌司: "World-Line Monte Carlo Study of the Dispersion Relation of an S=1" J.Phys.Soc.Japan. 63. 2866-2869 (1994)

Masashi Yamamoto：“S=1 色散关系的世界线蒙特卡罗研究”J.Phys.Soc.Japan 63. 2866-2869 (1994)。

Per Arne Rikvold: "Metastable lifetime in a kivetic Ising model" Physical Review. E49. 5080-5090 (1994)

Per Arne Rikvold：“基维伊辛模型中的亚稳态寿命”物理评论。

A. Kuroda and S. Miyashita: "Existence of Phase Transition in Ising-like Heisenberg Antiferromagnets on the Kagome Lattice" J. Phys. Soc. Jpn.64. 4509-4512 (1995)

A. Kuroda 和 S. Miyashita：“戈薇晶格上类伊辛海森堡反铁磁体中相变的存在”J. Phys。

M. Roji and S Miyashita: "Competition between Classical Ordered State and Quantum State in Ferromagnetic Chains Coupled by Antiferromagetic Bonds." J. Phys. Soc. Jpn.65(印刷中). (1996)

M. Roji 和 S Miyashita：“反铁磁键耦合的铁磁链中的经典有序态与量子态之间的竞争”，J. Phys Jpn.65（出版中）。

S. Miyashita: "Dynamics of the Magnetization with an Inversion of the Magnetic Field" J. Phys. Soc. Jpn.64. 3207-3214 (1995)

S. Miyashita：“磁场反转的磁化动力学”J. Phys。