Nonadiabatic Effect and Dynamic Compensation in a Spin-Boson System
Project/Area Number |
02640269
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Research Category |
Grant-in-Aid for General Scientific Research (C)
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Allocation Type | Single-year Grants |
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 |
Principal Investigator |
TSUZUKI Toshio Faculty of Science, Tohoku University, 理学部, 教授 (60037174)
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Project Period (FY) |
1990 – 1991
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Project Status |
Completed (Fiscal Year 1991)
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Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1991: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1990: ¥800,000 (Direct Cost: ¥800,000)
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Keywords | Dynamic compensation / Spin-boson system / Variational ground state / Tunneling-localization transition / Differential method to find thermal average / Thermodynamics and dynamics / Quantum tunneling system / Nonadiabatic effect / トンネリングー局転移在 / 二重井戸系 / 量子トンネル系 / 動的補償定理 / 分配関数 / 量子コヒ-レンスと散逸 / 二準位系の動力学 / 巨視的量子現象 |
Research Abstract |
1. Dynamics compensation theory has been proposed for a spin-boson system with a bilinear coupling between. Contributions from the zero-point and thermodynamic fluctuations are completely compensated by those from the dynamical fluctueltions of cohererly excited bosons in the infrared range of boson energy. We have to treat the adiabatic and nonadiababatic effects of the bosonic bath simultaneously. Those are inseparable ones from one another. 2. The ground stale has been formulated and studied variationally. This theory describes that in the ohmic case the tunneling-localization transition takes place at a critical coupling strength alpha_c = 1/2 in the white bath ffidt, which is different from 1 obtained by the adiabatic renormalization. 3. The thermodynamics and dynamics have been formulated. It has been found that the spin-boson interaction is exhausted by the ground state correlation. 4. A new method has been proposed to compute the thermal average by differential operation. On using this method we study the mechanics and next calculate the thermodynamic effect. 5. It has been shown that the dynamic compensation is a new concept of renormalization in a system with degenerate potentialftminima(quantum tunneling system)which is coupled to a bosonic bath by a bilinear interaction.
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Report
(3 results)
Research Products
(40 results)