兰州大学机构库 >物理科学与技术学院
开放量子系统动力学及束缚态研究
Alternative Titlehe dynamics and bound state in open quantum system
刘海滨
Thesis Advisor安钧鸿
2015-05-28
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword开放量子系统 束缚态 动力学
Abstract在本文中,我们提出从量子系统与其环境形成的复合系统的能谱特性角度来理解开放系统退相干动力学的研究方法。我们发现伴随着复合系统一个局域化的束缚态的形成,系统的退相干将表现出定性的不同。首先,我们将研究亚欧姆谱密度下的自旋-玻色模型。我们发现,系统的退相干将表现出随着其与环境耦合强度增强而趋于减缓甚至抑制的反常退相干行为;进一步对复合系统能谱特性的研究表明该反常退相干是复合系统束缚态的形成所导致的量子相变的动力学表现。其次,我们将研究扩展的非均匀Dicke模型。我们对腔场动力学的研究发现:随着系统非均匀参数的改变,其非平衡动力学表现出从单调衰减至零到振荡衰减至有限确定值再到无衰减振荡的定性不同的动力学行为,进一步的研究表明这些动力学行为分别对应于复合系统能谱中无束缚态、形成一个和两个束缚态。该结果提供了一种通过操控Dicke模型的非均匀性来实现超辐射量子相变及其不同动力学特性的调控方案。最后,我们将研究耗散J-C模型中的量子速度极限时间以及非马尔科夫度。我们发现复合系统束缚态的形成才是导致开放系统具有非马尔可夫效应和更小量子速度极限时间的物理原因。我们还提出了一种在电路量子电动力学中验证我们预测的实验方案。在本论文的研究中我们得到不少有趣的结论,我们期望这些结论对认识和理解开放系统中的退相干动力学有一定的帮助。
Other AbstractIn this thesis, we propose a method to understand the decoherence dynamics of open quantum system by studying the energy spectrum of the composite system consisted of the quantum system and its environment. We find that, with the formation of a localized bound state in the composite system, the decoherence of the open system shows a substantial difference. First, we will study the sub-Ohmic spin-boson model. It is found that, with the increase of the coupling strength between the system and the environment, the decoherence of the system shows a counterintuitive slowdown behavior, which we call as anomalous decoherence. Further study on the energy spectrum of the composite system reveals that the anomalous decoherence is a dynamical consequence of a novel quantum phase transition (QPT) induced by the formation of a bound state of the composite system. Next, we will study an extended inhomogeneous Dicke model. Our study on the dynamics of the cavity field shows that with the change of inhomogeneity, the nonequilibrium dynamics show rich behaviors, for example, an exponential decaying to zero, a damped oscillation to a finite value, or even a lossless periodic oscillation. Further study reveals that these behaviors correspond respectively to no bound state, one bound state, and two bound states are formed in the composite system. Our results suggest a scheme to realize the superradiant QPT and different dynamical behaviors by manipulating the inhomogeneities of the Dicke model. At last, we will study the quantum speed limit time and the non-Markovianity in a damped multimode J-C model. We find here that both the quantum speedup and the non-Markovianity originate from the formation of a bound state of the composite system. This gives a mechanism explanation to the physical reason of quantum speedup and non-Markovianity. An experimentally accessible scheme in cavity quantum electrodynamics (QED) platform is proposed for potentially testifying our prediction. In this thesis, some interesting results are obtained. We hope these results can contribute to the understanding of open quantum system dynamics.
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229653
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
刘海滨. 开放量子系统动力学及束缚态研究[D]. 兰州. 兰州大学,2015.
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