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题名	量子相干调控原子系统中原子局域化、压缩光以及共振荧光空间干涉特性研究
作者	金璐玲
学位类别	博士
答辩日期	2010
授予单位	中国科学院上海光学精密机械研究所
导师	龚尚庆
关键词	量子相干调控 原子局域化 原子纳米光刻 压缩光 相对相位 空间干涉
其他题名	Study on the quantum coherent control to the property of atom localization, squeezing and spatial interference from resonant fluorescence in atomic systems
中文摘要	自激光诞生以来，利用激光良好的相干性进行量子相干调控成为了近年来量子光学和激光物理等学科的交叉前沿研究领域。随着对量子相干调控领域研究的深入，人们发现了光与物质相互作用的很多新现象，如拉比振荡、相干布居捕获、 电磁诱导透明等等。这些新现象不仅对量子光学的基础和应用研究起到了重要作用，也对其他许多新兴与交叉学科的发展具有重要意义，如量子信息科学、光物理、光化学、光生物学、量子信息科学及阿秒科学等。 本论文主要就多能级原子系统中基于电磁诱导透明原理的原子局域化及其在原子纳米光刻领域的应用进行了系统的研究，并对强光场驱动下的多原子系统在产生压缩光以及空间干涉等方面进行了探讨，取得了一些创新性研究成果。主要包括： 1. 考虑一个碱土金属四能级原子系统，提出了驻波场相干调控原子局域化的方案。在控制场和驻波场分别与相对应的跃迁共振时，通过密度矩阵方法解析求解得到了探测场的吸收峰位置与半高全宽的表达式，并与数值分析进行了比较。通过调节驱动光场的失谐和拉比频率，可以把单位波长范围内发现原子的概率从1/4提高到1/3甚至1/2。并可以通过提高驻波场的拉比频率，或者降低探测场的失谐，来减小吸收峰的宽度，即提高局域化的精度。 2. 在四能级Ladder型原子系统中，探讨了利用双驻波场与原子系统的相互作用实现亚半波长原子局域化的可行性方案。我们研究发现两个驻波场对原子局域化行为的调控起着不同的作用：提高其中一个的拉比频率，能减少一个驻波波长内的吸收峰个数，提高探测几率，从而产生亚半波长原子局域化；提高另一个驻波场的拉比频率，能在保持亚半波长局域化以及探测几率为1/2时，提高局域化的精度。通过比较发现，在相同参数条件下，双驻波场相对于单驻波场与原子系统作用，对原子局域化更有利。 3. 提出了基于二维原子局域化的二维原子纳米光刻方案。两个正交的驻波场对多能级原子的相干调控作用使得原子的条件位置分布能在x和y两个方向同时受限，从而出现二维原子局域化。局域化的特性由光场参数控制。基于这种二维原子局域化，让通过正交驻波场后的原子沉积在xy平面的基底上，能制备得到折射率周期性变换的结构，从而可以用来实现纳米量级的原子光刻，且原子光刻的图样能通过光场调节。 4. 研究了被强光场驱动的一维线性排列的全同二能级原子散射光的压缩现象。原子链置于一个修正的真空库中，并且真空库在两个激光场缀饰的边带跃迁频率的模式密度与自由真空中的有偏离。我们发现，随着真空库与自由真空库环境的偏离增大，压缩程度会得到提高。通过真空库的修正消除了从规则排列原子结构中得到压缩光源只能使用低强度的驱动光的限制。与自由真空不同，修正真空库中，即使在共振的强光场驱动下，也能得到压缩光。 5. 利用环形结构中光场之间的相对相位，探讨了强光场驱动下两个原子共振荧光的空间干涉效应。光场的相对相位能打破强场作用下原子的布居平衡，从而可以利用对相对相位的调控，来恢复强场驱动下的干涉。为了消除相对相位不能严格等于π/2的限制，可以调节光场之间的相对强度，或者，用驻波场代替其中一个线偏振光场，调节观测屏与原子之间的相对距离，从而能提高实验操作的可行性。
英文摘要	Since laser was constructed in the 1960s, the study on quantum coherent control based on its excellent coherent property has become the frontier of the cross-research area of laser physics, quantum optics and other disciplines. With further and deeper research in quantum coherent control, more and more novel phenomena in the laser-matter interaction have been revealed, such as Rabi oscillation, coherence population trapping, electromagnetic induced transparency, et al. These novel phenomena give significant contributions not only to the understanding of the foundation of quantum optics and its applications, but also to the emergence and progress of new subjects such as quantum information, quantum computation, optical physics, optical chemistry, optical biology, quantum information and attosecond technologies and other rising or cross disciplines. In this thesis, we mainly investigate the quantum coherent control of atom localization and its application in nano-lithograph in atomic systems. We also study the squeezing light and spatial interference of the resonance fluorescence in strong light. The main innovative and important results are: 1. We propose an atom localization scheme for a four-level alkaline earth atom via a classical standing-wave field, and give the analytical expressions of the localization peak positions as well as the widths versus the parameters of the optical fields. We show that the probability of finding the atom at a particular position can be increased from 1/4 to 1/3 or even 1/2 by adjusting the detuning of the probe field and the Rabi frequencies of the optical fields. Furthermore, the localization precision can be dramatically enhanced by increasing the intensity of the standing- wave field or decreasing the detuning of the probe field. 2. We investigate a four-level ladder-type atomic system coupled by two classical standing-wave fields, and propose a scheme for sub-half-wavelength atom localization. We find that these two standing-wave fields play different roles in the localization scheme: increasing the Rabi frequency of one standing-wave field can increase the detecting probability and lead sub-half-wavelength localization, while increasing the Rabi frequency of the other standing-wave field can help in enhancing the localization precision with the detecting probability is kept to be 1/2. It is shown that, with the same optical parameters, using two standing-wave fields gives more advantages in localization, as compared to one standing-wave field case. 3. Based on two-dimension atom localization, we study the two-dimension atom nano-lithograph. By applying two orthogonal standing-wave fields, the atoms can be localized on some special positions, leading to the formation of sub-wavelength two-dimension periodic patterns. The pattern topographies can be modified by adjusting the intensities of the standing wave fields. 4. We investigate squeezing in light scattered from a linear chain of identical atoms driven by a strong field. The whole chain is embedded in a modified reservoir, with mode densities at the two dressed sideband transition frequencies deviating from the regular vacuum case. We found that the obtained squeezing enhances with increasing deviation of the reservoir from the standard vacuum case. The modification of the vacuum reservoir circumvents the usual restriction of squeezing in light scattered by regular structures of atoms to low incident light intensities. In contrast to the free space case, in a modified reservoir, squeezing also occurs with a resonant strong driving field. Our setup thus can act as a source of macroscopic squeezed light. 5. We study the phase control of spatial interference of resonance fluorescence from two duplicated two-level atoms, driving by two orthogonally polarized fields. We find that in the strongly driven situation, adjusting the relative phase leads to a redistribution of the atoms and a significant change of the atomic coherences, so that the pattern could survive. In order to improve the experimental realizability, we therefore propose a scheme to recover the visibility with fixed relative phase by adjusting the relative intensities between the two driving fields or alternatively by using a standing-wave field.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15625]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	金璐玲. 量子相干调控原子系统中原子局域化、压缩光以及共振荧光空间干涉特性研究[D]. 中国科学院上海光学精密机械研究所. 2010.

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