结构化光场环境中的量子速度极限

发布时间：2018-01-14 16:35

本文关键词：结构化光场环境中的量子速度极限　出处：《苏州科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文主要以结构化光场环境中的原子系统为研究对象,讨论三种典型退相干过程(振幅阻尼、相位阻尼和一般退极化)对量子态演化速度极限的影响,从而为开放系统的精密量子度量提供理论基础。我们提出了基于迹间距方法的量子速度极限判据,其中研究工作主要包含以下三个方面:首先,以Lorentzian频谱光场为例,我们考虑了具有振幅阻尼的Jaynes-Cummings原子-光场模型,发现当原子跃迁频率与光场中心频率存在强失谐时,环境与系统之间弱耦合作用可加速量子态演化,而强耦合作用能减缓量子态演化。我们又研究了具有相位阻尼的自旋-玻色子模型,在Ohmic-like频谱环境中,当增加截断频率或者超欧姆情形时,系统演化过程可以得到明显加速。研究结论表明:开放系统的量子加速潜质与能量或信息流动有关,可以用环境记忆能力(非马尔科夫效应)来解释。然后,我们考虑受外场调控的原子与光场模型,得到了开放系统的一般退极化过程。本文讨论了可调外场和环境温度对量子速度极限的影响。在改变外场强度时,我们能够观察到量子态演化从非加速到加速的转变。在Lorentzian频谱光场中,有限低温环境能促进量子态的加速演化。但是,在Ohmic-like频谱环境中,环境温度对量子速度极限影响不大。从理论上,我们可以实现低温环境中的单比特量子态演化加速。最后,本文研究含有多体量子纠缠的N个原子系统在三种典型的退相干过程中的量子速度极限。我们发现在振幅阻尼和一般退极化阻尼环境中,量子纠缠可以促进量子态加速演化。这是因为在这两个退相干过程中,基于多体量子纠缠态的原子系统能量流向的变化非常明显。但是,在相位阻尼环境中,量子纠缠态的演化速度极限没有任何变化。通过严格的数值计算,我们得到量子演化速度随着纠缠原子数目的增加而加快。
[Abstract]:In this paper, the effects of three typical decoherence processes (amplitude damping, phase damping and general depolarization) on the evolution velocity limit of quantum states are discussed. In order to provide a theoretical basis for the precise quantum measurement of open systems, we propose a quantum velocity limit criterion based on trace spacing method, in which the research work mainly includes the following three aspects: first. Taking the Lorentzian spectrum light field as an example, we consider the Jaynes-Cummings atom-light field model with amplitude damping. It is found that the weak coupling between the environment and the system can accelerate the evolution of quantum states when there is a strong detuning between the atomic transition frequency and the central frequency of the light field. The strong coupling can slow down the evolution of quantum states. We also study the spin-boson model with phase damping. In the Ohmic-like spectrum environment, when the truncation frequency is increased or superohmic case is increased. The results show that the quantum acceleration potential of the open system is related to energy or information flow, which can be explained by the environmental memory ability (non-Markov effect). The general depolarization process of the open system is obtained by considering the atomic and light field models regulated by the external field. The effects of the adjustable external field and ambient temperature on the quantum velocity limit are discussed in this paper. We can observe the transition of quantum state from non-acceleration to acceleration. In the Lorentzian spectrum light field, the finite low temperature environment can promote the accelerated evolution of quantum state. In Ohmic-like spectrum environment, ambient temperature has little effect on quantum velocity limit. Theoretically, we can accelerate the evolution of single-bit quantum state in low-temperature environment. Finally. In this paper, we study the quantum velocity limits of N atomic systems with multibody quantum entanglement in three typical decoherence processes. We find that in both amplitude damping and general depolarization damping environments. Quantum entanglement can accelerate the evolution of quantum states because the energy flow direction of the atomic system based on multi-body quantum entangled states is very obvious in these two decoherence processes. However, in the phase damping environment. There is no change in the evolution velocity limit of quantum entangled states. By strict numerical calculation we get that the quantum evolution rate increases with the increase of the number of entangled atoms.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O413

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