【作者】 邹红梅；

【导师】 方卯发；

【作者基本信息】 湖南师范大学 ， 光学， 2014， 博士

【摘要】 量子系统间的相互作用导致许多不同于经典物理的奇特量子效应——非经典效应。一般情况下,真实的量子系统是开放系统,它会与外部环境发生相互作用,从而导致其非经典效应的损伤甚至消失。如何选择合适的环境,通过量子调控技术保持或增强量子系统的非经典效应,是量子光学研究领域人们关心的热点问题。近年来人们注意到具有记忆效应的非马尔科夫环境对量子系统的动力学行为具有回复作用。那么,在非马尔科夫环境下,是否能通过量子调控技术实现量子系统的非经典效应的保持或增强?本文运用开放量子系统的基本理论研究了非马尔科夫环境下量子系统的非经典效应,取得了一些有创新意义的结果。主要内容如下：第一章简单介绍了非马尔科夫开放量子系统的基本理论和几种典型的量子非经典效应。第二章用时间消卷积主方程方法研究了与两个独立库失谐耦合的二能级原子系统的熵不确定度与纠缠见证。详细讨论了在量子存储支撑下,非马尔科夫效应和失谐量对熵不确定关系和纠缠见证的影响。结果表明：只有在全同的非马尔科夫库中,增大失谐和非马尔科夫效应才能减小测量输出的熵不确定度、减小熵不确定关系下限、增加纠缠见证时间、有效保持纠缠见证区域。这些结果在量子测量、量子密码和量子信息处理中具有实际应用价值。第三章基于第二章的模型,研究了两原子的压缩效应,发现两原子压缩同时依赖于失谐和非马尔科夫效应。结果表明：在非马尔科夫环境下,失谐越大、非马尔科夫效应越强,压缩效应保护得越好,而且当失谐和非马尔科夫效应同时存在时,两原子压缩能有效地长时间保持。该结果在自旋偏振测量、高精度原子钟制造等方面具有实际意义。第四章利用时间消卷积主方程方法研究了非马尔科夫环境中两原子-腔系统的纠缠动力学,首次得到了非马尔科夫环境下两原子-腔系统的精确解析解,并详细讨论了原子-腔耦合强度、非马尔科夫效应和初态纯度对纠缠动力学的影响。结果表明：两原子之间的纠缠与两腔模之间的纠缠可以相互交换,在短时间内,几对纠缠相互交换并振荡地衰减,当时间足够长时,四对纠缠会呈现单调减小的规律；获得了两原子-腔系统中任意两量子比特的纠缠稳态；提出了在原子-腔耗散系统中利用原子和腔之间的相互作用实现纠缠交换的方案；提供了在非马尔科夫环境中利用原子-腔之间的相互作用实现由一对纠缠态制备多对纠缠态的纠缠复制新方法。该结果在量子信息、量子通信、量子计算等许多领域中都起着极其重要的作用。第五章利用时间消卷积主方程方法,分别针对洛伦兹谱密度和具有Lorentz-Drude截断频率的欧米伽谱密度的环境,研究了两原子之间的量子谐错,讨论了非马尔科夫环境的性质对量子谐错的影响。结果表明：在不同性质的非马尔科夫环境中,量子谐错都能得到很好的保持,而且非马尔科夫效应越强、失谐量越大,量子谐错的鲁棒性越好。第六章基于第五章的模型,研究了不同非马尔科夫环境中两原子激发态的布居囚禁,讨论了非马尔科夫环境的性质对原子布居囚禁的影响。结果表明：在不同性质的非马尔科夫库中,两原子激发态布居都能得到很好的囚禁,而且非马尔科夫效应越强、失谐量越大,两原子激发态布居的囚禁效果越好。第七章对全文进行了总结与展望。更多还原

【Abstract】 Non-classical effects of quantum system are peculiar quantum effects different from the classical physics, which are caused by interactions between quantum sys-tems. Generally, interactions with outside environments will destroy non-classical effects of open quantum systems. It has become a hot issue in the quantum optics field how to maintain or enhance non-classical effects of open quantum systems by quantum controlling technology. In recent years, it has been noted that the mem-ory effects of non-Markovian environments can make the dynamical behaviors of quantum systems recovered. Whether can the non-classical effects be maintained or enhanced by quantum controlling technology in non-Markovian environments? The aim of this paper is to investigate the non-classical effects of two independent two-level atoms in non-Markovian environments. The main contents are as follows:1.Several typical non-classical effects of quantum system and the basic theory of open quantum system are introducted briefly.2.The quantum entropic uncertainty and entanglement witness in two-atom system coupling with non-Markovian environments is studied by the time-convolutionless master-equation approach. The influence of non-Markovian effect and detuning on the quantum entropic uncertainty relation and entanglement witness in the presence of quantum memory is discussed in detail. The result shows that, only when two non-Markovian reservoirs are identical, the increasing detuning and non-Markovian effect can cut down the entropic uncertainty of measurement outcomes, reduce the lower bound of the entropic uncertainty relation, increase the time re-gion during which the entanglement can be witnessed, and effectively protect the entanglement region witnessed by the lower bound of the entropic uncertainty rela-tion. The results can be applied in quantum measurement, quantum cryptography task and quantum information processing.3.The squeezing dynamics of two atoms is researched, based on the model of Chapter2. The results show that, in the non-Markovian regime, the bigger the detuning and the stronger the non-Markovian effect are, the better the squeezing is preserved. And the squeezing of two atoms can be effectively protected for a long time when both non-Markovian effect and detuning are present simultane-ously. The results would be useful in high-precision measurement and quantum communication.4.Analytical solution and entanglement swapping of two atom-cavity system, where each cavity is coupled to a Lorentzian reservoir, has been investigated by the non-Markovian master equation method. We first gain the analytical solution of two atom-cavity system in non-Markovian environments and discuss in detail the influence of the atom-cavity coupling, the non-Markovian effect and the initial state purity on the entanglement dynamics and the entanglement swapping. The results show that, the entanglement can be swapped between any two qubits by the interaction, such as between two atoms, between two cavities and between a atom and its cavity. In a short time, several pairs of entanglement alternate and decrease oscillate damply, but after a long time, four pairs of entanglement will decrease monotonically. We obtain two steady entanglement states in Marko-vian and non-Markovian regimes, respectively, and put forward an entanglement swapping scheme utilizing interaction atom with cavity in two atom-cavity dissi-pative system, and provide a new way copying entanglement that several pairs of entanglement can be simultaneously prepared by a pair of entanglement in non-Markov environments. The results will play a crucial role in quantum information, quantum communication and quantum computing.5.The quantum discord of two atoms, which are in two Ohmic reservoirs or in two Ohmic reservoirs with a Lorentz-Drude cutoff function, respectively, is considered. We find that, the quantum discord can be effectively protected not only in Lorentzian reservoirs but also in Ohmic reservoirs with a Lorentz-Drude cutoff function, and the bigger the detuning and the stronger the non-Markovian effect are, the better the robustness of the quantum discord is.6.The population dynamics of two atoms is discussed by means of the idea of Chapter5. The results show that the two atoms can be effectively trapped in the excited states not only in Lorentzian reservoirs but also in Ohmic reservoirs with a Lorentz-Drude cutoff function.7.A summary and outlook is presented.更多还原