【作者】 杨希华；

【导师】 孙真荣；

【作者基本信息】 华东师范大学 ， 生物学， 2005， 博士

【摘要】 近年来，量子相干控制在诸如高灵敏高精度激光光谱和新型量子频标、分子运动和物理化学反应的操控、原子分子激发态结构信息、量子态绝热布居转移、量子计算和量子信息处理等方面具有广泛的应用而受到人们的关注。基于量子干涉效应而产生的相干控制可分为频域和时域内的两种：频域内的量子相干控制来源于两个或多个同时的不同跃迁路径间的干涉，时域内的量子相干控制来源于两个或多个具有一定延时的同一跃迁路径间的干涉。本文旨在从理论和实验两方面对以往较少涉及的原子及原子-分子混合体系中基于非相干碰撞而产生的频域和时域内多能级系统量子相干控制效应进行研究，并着重探索量子相干控制产生的条件及其对外界条件的依赖关系等。 对于时域内的多能级系统量子相干控制，首次报道了在钠原子-分子混合体系中基于等频混合激发和离共振碰撞感应激发而产生的钠原子两延时跃迁3P-5S(或4D)相干涉而产生的Ramsey条纹的实验观察，并通过测量干涉信号随外界条件(缓冲气压和温度)的变化关系进一步在实验上确认。同时通过求解薛定谔方程分析了碰撞引起的激发态驰豫速率、两碰撞激发跃迁几率比及分子-原子碰撞能量转移速率等因数对干涉效应的影响，揭示了通过碰撞这种非相干过程可实现时域内的多能级系统量子相干控制。 对于频域内的多能级系统量子相干控制，运用半经典理论首次研究了一个含菱形的开放五能级系统中基于碰撞感应激发而产生的间距较大双能级间的相干及量子干涉相消效应。分析了碰撞引起的相干和非相干驰豫速率、激光拉比频率、相邻两能级间距、不同跃迁偶极矩比等因数对干涉效应的影响；揭示了通过碰撞这种非相干过程可实现间距较大双能级间的相干叠加，从而产生量子干涉。同时运用缀饰态理论，对干涉产生的条件、干涉特性给出明了的物理公式；对碰撞产生的相干相消给出了清晰的物理图象。 运用半经典理论，在考虑了探测场所有高阶项的情况下，通过求解含时密度矩阵方程研究了不同能量抽运场作用下Λ型三能级系统的瞬态电磁感应透明特性，分析了不同能量抽运场作用下弱探测场的吸收、各能级布居及相干项ρ23更多还原

【Abstract】 Recently, quantum coherent control has attracted considerable interest due to its extensive applications, such as to obtain ultrahigh-resolution spectroscopy and frequency metrology, to control molecular motion and chemical reactions, to get information on atomic or molecular excited states, to achieve coherent rapid adiabatic population transfer, and to realize quantum computation and quantum information processing. There exist two kinds of quantum interferences which underlie quantum coherent control. One refers to the interference between two or more different transition pathways connecting the same initial or final state in the frequency domain, and the other refers to the interference between two or more time-separated transition pathways connecting the same initial and final states in the time domain. In this thesis, we try to theoretically and experimentally investigate collision-induced quantum coherent control in both the time and frequency domains in atomic multi-level system and atom-molecule hybrid system to find the conditions for generating quantum coherent control, and the dependence of quantum coherent control on the environmental conditions.In the case of quantum coherent control in the time domain, we report the experimental observation of the quantum interference between two time-delayed 3P-5S （or 4D） transition pathways realized through the atomic collision-assisted two-step excitation and atom-molecule hybrid excitation by a single nanosecond laser pulse in the Na₂-Na system. By solving the time-dependent Schr（o|¨）dinger equation, we study the effects of the ratio of the two collision-assisted transition probabilities, collision energy transfer rate, and collision-induced decay rate of the 5S （or 4D） state on the interference fringes. It is clearly shown that temporal coherent control of quantum amplitudes can be realized through the incoherent collisions.In the case of quantum coherent control in the frequency domain, we theoretically study the collision-induced destructive interference in an open rhomb-type five-level system with a widely-separated doublet. By using the density更多还原