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Acta Physica Sinica

VARIArl0NAL STUDY OF ADISSIPATIVE QUANTUM TUNNELING SYSTEM

Shi Yun-long，Chen hong，Wu Xiang

Published Jan 1, 1991• 0 citations
Publisher

Abstract

摘要 本文用变分法研究了耗散量子系统中的声于基态及其对局域一退局域相变条件的影响.发现: 1. 声子基态不仅存在通常的位移效应, 而且还有形变效应. 本文提出的位移一压缩态可同时描述这两种效应; 2. 声子基态的选择对相变条件有很大影响.随着声子基态能量下降,相变曲线将向强祸合方向移动. Abstract The ground states of phonons in dissipative quantum tunneling system and their influences on the localization delocalization transition are investigated by a variational approach. We find that: 1.There are two kind of influences, displacement and deformation, on phonon describe both these influences. 2. The localization-delocalization transition depends on the choice of phonon ground state. The transition will occur at strong coupling as the energy of the ground state decreases. 作者及机构信息 石云龙；陈鸿；吴翔 1. 雁北师范学院物理系；同济大学物理系 Authors and contacts Shi Yun-long Chen hong Wu Xiang 参考文献 施引文献

DOI
10.7498/aps.40.1162

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Acta Physica Sinica•Jan 1, 1989•0 citations
摘要 本文用变分法研究了耗散量子系统中的声于基态及其对局域一退局域相变条件的影响.发现: 1. 声子基态不仅存在通常的位移效应, 而且还有形变效应. 本文提出的位移一压缩态可同时描述这两种效应; 2. 声子基态的选择对相变条件有很大影响.随着声子基态能量下降,相变曲线将向强祸合方向移动. Abstract The ground states of phonons in dissipative quantum tunneling system and their influences on the localization delocalization transition are investigated by a variational approach. We find that: 1.There are two kind of influences, displacement and deformation, on phonon describe both these influences. 2. The localization-delocalization transition depends on the choice of phonon ground state. The transition will occur at strong coupling as the energy of the ground state decreases. 作者及机构信息 石云龙；陈鸿；吴翔 1. 雁北师范学院物理系；同济大学物理系 Authors and contacts Shi Yun-long Chen hong Wu Xiang 参考文献 施引文献
摘要 采用变分方法，比较了超欧姆耗散两能态系统中位移变分态和位移－压缩变分态的特性。通过研究发现，在强耦合区域，位移－压缩态较稳定，其基态性质不仅取决于谱密度，而且还依赖于耦合强度ｇ1～ω1λ的指数λ；位移－压缩态稳定的区域将随λ减小而增加。对于欧姆耗散两能态系统，在位移－压缩态退局域相区域亦有同样的特性，且该区域亦随λ减小而增加。 Abstract The properties of two variational states, the displaced state and the displaced-squeezed state, are compared for a two-state system with superohmic dissipation by a variational approach. We find that, in strong coupling region, the displaced-squeezed state is the more stable and the ground-state properties depend not only on the spectral density but also on the index λ of the coupling strength ｇ1～ω1λ(ω1 is phonon frequenceis). Moreover, we obtain that the stable area of the displaced-squeezed state increases as λ reduces. Similar properties have been obtained for ohmic dissipation and it is shown that the delocalization area of the displaced-squeezed state increases as λ reduces. 作者及机构信息 石云龙2, 聂一行2, 陈鸿1, 吴翔1 (1)同济大学物理系; (2)雁北师范学院物理系 基金项目: 国家自然科学基金和山西省自然科学基金资助的课题. Authors and contacts SHI YUN-LONG2, NIE YI-HANG2, CHEN HONG1, WU XIANG1 (1)同济大学物理系; (2)雁北师范学院物理系 参考文献 施引文献
The ground states of phonons in a dissipative quantum tunneling system and their influences on the localiza ion-delocalization transtion are investigated by a variational approach. We find that: 1. There are two kind of influences, displacement and deformation, on phonon states due to coupling with a tunneling particle, and displaced -squeezed states are proposed to describe both these influences. 2. The localization-delocahzation transition depends on the choice of phonon ground state. The transition will occur at strong coupling as the energy of the ground state decreases.
We present a systematic analysis of the ground state properties of a tunneling system coupled to an Ohmic bath. The nonadiabatic effects induced by coupling with tunneling particle, on the ground state properties of phonons are taken into account. For this we have considered both displacement and deformation of phonons via a variational treatment. The symmetry breaking transition, or the delocalization-localization transition, of the tunneling particle is presented and is compared with earlier known results. We also show that in the critical regime a gap will be opened near the zero momentum in the spectrum of the phonons. The modified phonon spectrum along with the phonon displacement field correlation functions have been calculated. It is shown that in the critical regime the tunneling system stabilizes the lattice against long wavelength fluctuations.