【作者】 杨雄；

【导师】 匡乐满；

【作者基本信息】 湖南师范大学 ， 理论物理， 2007， 硕士

【摘要】 量子信息理论已成为现代物理学和信息科学中最前沿的学科之一,并以空前的速度发展,取得许多骄人的成绩。纠缠在量子信息理论中有着举足轻重的地位。“纠缠”被用来表征组成系统的态不能够被分解为系统的子系的态的直积形式。纠缠意味着分离的两个子系统之间的关联,说明了量子的非局域性现象。另一方面,纠缠也是进行诸如量子计算、量子纠错、量子稠密编码和量子隐形传态等量子信息工程的重要资源。因此,对量子纠缠问题作深入的研究,如,如何制备量子纠缠态,如何量度量子纠缠态的纠缠程度,环境对量子纠缠的影响等,成为我们研究的一个重要任务。本文将重点研究量子纠缠态的制备,量子纠缠的动力学演化以及量子纠缠态在量子通信中的应用。全文共分为七章。第一章回顾量子纠缠的发展历程,以及量子纠缠的研究进展和现状;第二章简单介绍量子纠缠的有关理论,包括量子纠缠态的定义,量子纠缠态的度量及纠缠的判别,此外,还介绍了几种在量子信息中有重要意义的纠缠态;第三章阐述有关腔QED的基本理论,这也是我们工作的重要基础。四——六章是我们独力的工作。在第四章中,我们研究了如何在与腔相互作用的原子系综之间制备双模压缩相干叠加态,并讨论了所制备态的非经典性质;第五章中,我们讨论了环境对纠缠的影响,研究了两个全同二能级原子同时与单模耗散腔场发生大失谐相互作用时,原子-场系统、两原子子系统的线性熵演化,以及原子的初始状态与腔的耗散因素对各线性熵的影响;第六章,我们提出了一个利用耦合双原子同时与大失谐的双光子Jaynes-Cummings模相互作用实现量子信息转移的方案。第七章,我们对全文作了简单的总结,并对量子纠缠态的应用前景作了一些展望。更多还原

【Abstract】 Quantum inforamtion theory is one of the frontier disciplines in modern physics and informatics,and has a great deal of proud achievements.Entanglement plays a key role in quantum information theory.Entanglement is one of the most striking feature of quantum mechanics.This term "entanglement" is used for states of a composite system that can’t be separated into the product of states of subsystems.Entanglement implies the correlation between separated subsystems and indicates the phenomenon of quantum nonlocality. On the other hand,entanglement is also an important resource that performs quantum information processing,such as quantum computation,quantum errorcorrecting codes,quantum dense coding and quantum teleportation.Hence, studies on quantum entanglement problems,for example,how to prepare quantum entangled states,how to measure the degree of entanglement for quantum entangled states,effect of the environment on quantum entanglement,and so on,are of significance.This thesis mainly discusses preparation of entangled states,dynamics of quantum entanglement and the application of entangled states in quantum communication.The thesis consists of seven chapters.In the first chapter,we briefly recall the developing course of quantum entanglement,present status for research of quantum entanglement.In the second chapter,we present an introduction to basic theory on quantum entanglement,including definition,measurement and judgement of quantum entanglement states.We also review some important entangled states in quantum information.In the third chapter,we describe the basic theory on cavity QED,which is the basis of our studies.In the fourth chapter,we investigate how to prepare superposition states of two-mode squeezed coherent sates in atomic ensembles interacting with cavity fields,and study non-classical properties for these superposition states.In the fifth chapter,we investigate effect of envinronment on entanglement, discuss the evolution of the linear entropies of atom-field system,in which two identical two-level atoms simultaneously interact with a single-mode dissipative cavity field under large detuning.The effects of the initial atom states and the dissipative factors of the cavity on all linear entropies are also discussed.In the sixth chapter,we present a scheme for transferring quantum information based on Jaynes-Cummings-type,interaction between two atoms,and atom and cavity field.In the last chapter,we give a simple summary to the above works and prospect applications of quantum entangled states.更多还原