Relaxation of metastable state through the quantum dynamics

通过量子动力学弛豫亚稳态

• 批准号: 10044084
• 负责人: MIYASHITA Seiji
• 金额: $ 4.8万
• 依托单位: The University of Tokyo (1999)Osaka University (1998)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10044084/
• 关键词: quantum spin system; quantum Monte Carlo; nanoscale magnets; ESR; nonadiabatic transitions; photoinduced phasetransition; 量子モンテカルロ法; 準安定緩和; 量子ダイナミックス

We have studied the following phenomena in which the, quantum dynamics plays an important role. We investigated the quantum hysteresis phenomena in nanoscale molecular magnets such as Mn12, Fe8 and V15 in the view point of non adiabatic transition. We studied the effects of the environments, such as the phonon, the dipole interaction and hyperfine interactions with the nuclear spins, on the quantum dynamics. In particular, we clarified mechanisms of deceptive non-adiabatic transition at very low temperature, of the parity effect due to the thermally excited states and of the quantum foehn phenomena due to inflow of the heat. We also developed a new direct numerical method to study the line shape of ESR in strongly interacting quantum spin systems, and investigate the dynamical shift due to the dipole interaction, anisotropy and DM interactions. The slow dynamics due to the inhomogeneity in the systems such as spin glass and random bond system. In quantum systems, the local magnetization is often induced at inhomogeneous parts of lattice in the so-called gapped quantum spin systems which is non-magnetic in the ground state. We studied how the local magnetizations are induced in various systems and also investigate the dynamical properties. We also investigated the quantum spin dynamics for quantum computing, and found a kind of instability in the spin manipulation.

我们研究了以下现象，量子动力学在其中扮演着重要的角色。从非绝热跃迁的角度研究了纳米分子磁体如Mn12、Fe8和V15的量子磁滞现象。我们研究了声子、偶极相互作用和超精细相互作用等环境对量子动力学的影响。特别是，我们阐明了极低温度下的欺骗性非绝热跃迁、由于热激发态引起的宇称效应和由于热流入而产生的量子烟现象的机制。我们还发展了一种新的直接数值方法来研究强相互作用量子自旋系统中ESR的线形，并研究了由于偶极相互作用、各向异性和DM相互作用引起的动力学位移。由于自旋玻璃和随机键系统中的不均匀而导致的慢动力学。在量子系统中，在基态非磁性的带隙量子自旋系统中，局域磁化常常发生在晶格的非均匀部分。我们研究了各种系统中局域磁化是如何产生的，并研究了它的动力学性质。我们还研究了用于量子计算的量子自旋动力学，发现在自旋操纵中存在一种不稳定性。

项目成果

Seiji Miyashita et al.: "Relaxation of Metastable Sates Quantum Fluctuation"IJMPC. 10. 1419-1426 (1999)

Seiji Miyashita 等人：“亚稳态量子涨落的松弛”IJMPC。

X.Hu,S.Miyashita and M.Tachiki: "Monte Carlo Simulation on the First-Order Melting Transition of High-T_c Supercon-ductors in B c" Phys.Rev.B58. B58. 3438-3445 (1998)

X.Hu、S.Miyashita 和 M.Tachiki：“B c 中高温超导体一阶熔化转变的蒙特卡罗模拟”Phys.Rev.B58。

Keiji Saito et al.: "Energy Transport in the Integrable System in Contact with various Types of Pohonon Reservoirs"Phys. Rev. E. 61. (2000)

Keiji Saito 等人：“与各种类型 Pohonon 储层接触的可积分系统中的能量传输”Phys。

C.Pich,A.P.Young,H.Rieger and N.Kawashima: "Critical Behavior and Grifriths-McCoy Singularitigs in the Two-Dimensional Random Quantum Ising Ferromagnet" Phys.Review detters. 81巻. 5916-5919 (1998)

C.Pich、A.P.Young、H.Rieger 和 N.Kawashima：“二维随机量子 Ising 铁磁体中的临界行为和 Grifriths-McCoy 奇异性”Phys.Review 第 81 卷。5916-5919 (1998)

Masamichi Nishino et al.: "Local magnetic structure due to inhomogeneity of interaction in S=1/2 antiferromagnetic chain"Phys. Rev. B. 61.6. 4033-4040 (2000)

Masamichi Nishino 等人：“由于 S=1/2 反铁磁链中相互作用的不均匀性而导致的局部磁性结构”Phys。