原子与光腔耦合系统中量子关联和稠密编码的研究

发布时间：2018-09-15 20:10

【摘要】：量子信息学是最近发展的最快及最热门新学科。量子纠缠作为这一学科极为重要的特性,在整个量子信息的度量与处理过程中提供核心的量子资源。量子纠缠是两个或多个量子系统中间存在的一种非定域,与经典关联有着本质上的区别。量子隐形传态,量子稠密编码,量子密钥分配等都是通过量子纠缠这种现象得以实现的。随着科学家们对于量子信息各种现象的了解和深入的发现,量子纠缠还是无法完全描述所有的量子关联。2001年ollivier和zurek引入了一种描述量子关联的物理量(称为量子失协)。量子失协的计算方法是系统的总关联和经典关联的差值。量子失协和量子纠缠的不同点在于,比如对于分离态而言,其纠缠值为零,但是量子失协的值可能不为零。这表明它比纠缠更为广泛。为此人们对量子失协的研究产生了极大的兴趣。从此种角度来看,量子失协的研究对量子资源的寻找是有潜在意义的。在这篇论文中,先介绍了量子信息的发展过程。重点叙述了量子纠缠的基本知识和量子纠缠的概念及其量子纠缠的应用及几种纠缠度量方式。其次详细介绍了量子失协和几何量子失协的概念和度量方式以及近期的一些实验进展。以原子与光腔耦合系统作为模型,分析了对双J-C原子与孤立原子系统中的各种量子关联的动力学演化。最后一步利用三重J-C模型实现量子稠密编码以及对单J-C原子与孤立原子系统中的部分各种量子关联的动力学演化进行了讨论与详细探究。研究内容以三个方面来介绍:一:以单Jaynes-Cummings(J-C)二能级原子和孤立原子构成的模型为研究对象,详细讨论了此模型中的局部量子关联。借用Dakic等人引入的衡量量子失协的方式。仔细分析了系统中两原子间量子失协的演化特性,与此同时也给出了量子形成纠缠的演化。从结果中发现,当系统在W态时由提高纯度以及两原子间的初始纠缠度可以提高系统的量子失协。而在这过程中非最大纠缠态的纠缠度对量子形成纠缠没有直接影响。光子数和原子与腔之间的耦合常数在量子关联演化过程中同样起着很重要的作用。二:以双J-C模型为研究对象,观察了此模型中各种量子关联随时间的变化关系。仔细观察了两原子在W态时的纯度,两原子间初始纠缠度及光子数等系统参量对量子纠缠变化的贡献。此过程中对相应变量进行了控制以便了解各个参数对量子纠缠的贡献。这个过程中也一起考虑了量子失协以及几何量子失协随时间演化的影响。从结果中发现以升高初始态的纯度及纠缠度带来各种量子关联的值的提升,也就是初始态的纯度和初始纠缠度对量子关联有着积极的作用。尤其是在光子数为零的时刻,几何量子失协及量子纠缠的振幅衰减震荡变为等幅震荡而量子失协的值为零。而光子数为非零时,各种量子关联的值随时间振荡衰减而震荡程度不一样,原子与腔系统的原子数越多量子关联取得值匀为高一些。三:考虑三重Jaynes-Cummings模型,讨论了引用此系统完成量子稠密编码的过程。当三个原子都在W态时,考虑原子间初始纠缠度及耦合常数等系统参量对稠密编码信道容量的影响。从演化图中发现以改变初始态的纠缠度从而改变稠密编码信道容量,初始纠缠度对量子关联同样起着积极作用,同样的对量子稠密编码也是不例外。耦合常数是改变演化过程的频率,耦合常数大频率也随着变大。
[Abstract]:Quantum information science is the fastest developing and most popular new subject in recent years. Quantum entanglement, as an extremely important characteristic of this subject, provides the core quantum resources in the measurement and processing of quantum information. Quantum entanglement is a kind of non-locality existing between two or more quantum systems and has an essential region with classical correlation. No. Quantum teleportation, quantum dense coding, and quantum key distribution are all realized by quantum entanglement. With the understanding and discovery of various phenomena in quantum information, quantum entanglement still can not describe all quantum correlations. In 2001, Ollivier and Zurek introduced a description of quantum. The difference between quantum discord and quantum entanglement is that, for example, for a separated state, the entanglement value is zero, but the quantum discord value may not be zero. This shows that it is more extensive than entanglement. In this paper, the development of quantum information is introduced firstly. The basic knowledge of quantum entanglement and the concept of quantum entanglement, the application of quantum entanglement and several kinds of entanglement are described emphatically. Secondly, the concepts and measurements of quantum and geometric quantum dislocations are introduced in detail. The dynamical evolution of various quantum associations between a double J-C atom and an isolated atom system is analyzed by using the coupled atom-cavity system as a model. Finally, the quantum quantities are realized by using the triple J-C model. The sub-dense coding and the dynamical evolution of some quantum correlations between a single J-C atom and an isolated atom are discussed in detail. The contents of the study are introduced in three aspects: 1. Taking the model of a single Jaynes-Cummings (J-C) two-level atom and an isolated atom as the research object, the localities of the model are discussed in detail. Partial quantum correlation. By using the method introduced by Dakic et al. to measure quantum dissociation, the evolutionary characteristics of quantum dissociation between two atoms in the system are analyzed in detail. At the same time, the evolution of quantum entanglement formation is also given. The entanglement degree of the non-maximally entangled state has no direct effect on the entanglement formation. The photon number and the coupling constant between the atom and the cavity also play an important role in the evolution of the quantum correlation. 2. Taking the double J-C model as the research object, the time dependence of various quantum correlations in the model is observed. The contribution of the system parameters such as the purity of two atoms in W state, the initial entanglement between two atoms and the number of photons to the quantum entanglement is carefully observed. The results show that the initial state purity and the initial entanglement have positive effects on the quantum correlation. Especially when the photon number is zero, the geometric quantum dislocation and the amplitude attenuation oscillation of the quantum entanglement become oscillatory. When the number of photons is non-zero, the values of various quantum correlations decay with time and oscillate differently. The more the number of atoms in the atom-cavity system, the higher the value of the quantum correlation is. 3. Considering the triple Jaynes-Cummings model, we discuss the over-use of this system to complete quantum dense coding. When all three atoms are in the W state, the influence of the initial entanglement and coupling constant between atoms on the capacity of dense coding channel is considered. Coding is no exception. Coupling constants change the frequency of the evolution process, and the large frequency of coupling constants increases with it.
【学位授予单位】：新疆师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O413

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