兰州大学机构库 >物理科学与技术学院
运动级联型三能级原子双光子过程中的熵及原子粒子布局数演化的研究
Alternative TitleEvolution of atom entropy and population in a moving cascade three-level atom in a two-photon process
张金芳
Thesis Advisor谭磊
2008-05-28
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword双光子 级联三能级原子 布局数
Abstract本论文主要讨论了运动级联型三能级原子双光子过程中的熵动力学及原子粒子 布局数的演化规律。 首先,我们简要介绍了J-C模型的提出和量子光学的建立。然后就J-C模型的重 要性和历史局限性做了简要说明。接着作为一种研究光场与原子相互作用的重要手 段引入了熵。 论文第二部分里,我们首先介绍了量子光学中的P-K熵理论及其研究现状。然 后简单的介绍了具有原子运动的双光子J-C模型的场约化密度矩阵的研究方法,从 而为我们要研究的模型在处理方法上提供了一定的理论基础。 论文的第三部分,我们在引言里简单介绍了有关¥型三能级原子熵理论的研究 现状,从中找出我们所要进行的研究的出发点。在第二节,运用全量子理论,在旋 波近似和偶极近似下,导出了考虑原子运动的级联三能级原子与单模场在简并双光 子共振跃迁下相互作用系统的波函数。在第三节,我们利用P-K熵理论,借助已导 出的波函数,通过数值计算,具体讨论了当运动原子初始处于相干叠加态时,原子 运动、场模函数和初始场的平均光子数¹n对场(原子)熵的影响。结果表明:熵演化 的周期依赖于原子的运动和场模函数的取值,而初始场的平均光子数¹n只影响最大和 次最小熵值,不改变熵演化的周期。 在论文的第四部分,我们仍利用已导出的波函数,数值计算了运动级联三能级 原子双光子过程中原子粒子布局数的演化特点。结果表明:原子粒子布局数的周期 崩塌与回复的拉比振荡和原子运动、场模函数和初始场的平均光子数¹n均有关。初始 场的平均光子数¹n越大,场模函数越小,都会使拉比振荡频率越高。原子粒子布局数 的演化周期只与场模函数有关,场模函数越大周期越长;而光强的大小不影响原子 粒子布局数演化的周期。
Other AbstractIn the second part the theories of entropy about phoenix-knight are introduced ,the currently study status quo on it are also investigated.Then,the resolved method of induced density matrix of entropy in a moving J-C model through a two-photon process are given,so it is provided a theory base on the approach treatment for what we will discuss. In the first section of Chapter3.we simply introduce several conception about quantum entropy;then ,some applications and the currently study status of the en- tropy in ¥type three-level atom are given.In the second section,Under the rotating- waves approximation and dipole-dipole approximation,we calculate the wave function of the interacting system which a moving cascade three-level atom interacting with a single filed through two-photon transitions by using of full quantum theory.In the third section,By use of the theory of P-Kentropy,in virtue of the deduced wave function,we have discussed the in°uence of the atomic motion,the field-mode structure parameter and the initial average photon number on the evolution of the entropy,when the atom is initially in coherent state.The results show that the entropy evolution period of the field is dependent of the atomic motion and the field-mode structure parameter.However,the parameter of the initial average photon number will neither lengthen nor shorten the entropy evolution period of the field,but the numerical values of maximum and sub- minimum of entropy will be affected by it. In the Chapter4,under the same condition, also in virtue of the deduced wave function,we have studied the population properties of the atom.The results show that the rabi oscillation of periodically collapsed and revival of the atom population is relevant of the atomic motion,the field-mode structure parameter and the initial aver- age photon number.the larger the parameter of the initial average photon number,the higher frequency of the rabi oscillation.Just like, the smaller the field-mode structure parameter,the higher frequency of the rabi oscillation.However,the period of the atom population only depends on the field-mode structure parameter.the larger of it,the longer period .but,the initial average photon number will neither lengthen nor shorten the period of the atom population.
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229031
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
张金芳. 运动级联型三能级原子双光子过程中的熵及原子粒子布局数演化的研究[D]. 兰州. 兰州大学,2008.
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