微纳结构下的量子态操控

发布时间：2018-03-01 01:18

本文关键词： 微纳结构共振荧光量子纠缠热化　出处：《兰州大学》2016年博士论文　论文类型：学位论文

【摘要】：微纳结构是尺寸居于分子尺度和微米之间的物体结构。在量子光学中,由于微纳结构中的电磁模式具有很强的空间局域效应,它是实现光与物质强相互作用和对量子系统进行状态操控的重要平台。在量子信息中,微纳结构以其全固态特性成为可集成单光子源和信息存储、转换与传输等光子器件的理想载体。在本文中,我们基于开放量子系统主方程方法,一方面研究了表面等离子体微纳结构中介观量子点的共振荧光和光力系统中机械振子之间稳定量子纠缠的制备,另一方面通过非平衡动力学的方法研究了平衡态统计力学中正则热化的成立条件。首先,我们研究了置于层状表面等离子体微纳结构中的量子点在共振驱动下荧光辐射的功率谱和关联统计特性。在原子系统发展起来的传统共振荧光理论主要基于偶极近似,但是我们研究发现,由于量子点空间尺寸的扩展和表面等离子体诱导的场强在空间的急剧变化,量子点的四阶矩对其荧光特性具有显著影响:一方面偶极近似下量子点荧光谱随量子点空间朝向的π旋转对称性被破坏,另一方面通过对量子点空间朝向和四阶矩的合理选择,荧光谱可以实现在单峰和Mollow三峰结构之间的转变;二阶关联函数也可以实现从单光子弱辐射区域向强辐射区域转变。我们的工作对利用量子点介观效应开发以量子点为载体的纳米单光子器件具有启发意义。其次,基于光力系统,我们提出了一种通过库工程制备单腔中双振动机械振子之间稳定量子纠缠的方案。热噪声的存在使得在宏观机械运动系统中基本不能观察到量子相干效应,光力系统提供了通过利用光与机械振子辐射压来降低机械振子热振动噪声的理想平台,因此使得在宏观机械运动物体上观察到量子纠缠特性成为可能。与以往广泛采用的方案不同,我们提出了一种制备单腔中双振动镜面稳定量子纠缠的新方案,我们的方案不诉诸于对机械振子热振动噪声的预冷却,主要利用了压缩库工程的思想:我们发现通过对腔场引入一个宽带压缩驱动场,两个镜面可以获得稳定的量子纠缠。分析表明其机制来自于腔所起的媒介作用:腔将它从宽带压缩驱动场中获得的量子压缩特性传递给了双镜面的相对动量,从而使得双镜面稳态表现出量子纠缠这一集体量子关联特性。我们的方案提供了一种无需预冷却实现机械运动系统稳定纠缠制备的方案。最后,通过研究量子谐振子在有限温度平衡环境中趋于平衡的动力学,我们从微观角度探讨了平衡态统计物理中正则热化的成立条件。从微观角度认识统计物理基础—各态历经假说的物理依据及评估其成立范围是统计物理的核心问题。前人研究发现任意复合系统的纯态都将伴随开放系统的正则热化,该结果暗示了正则热化的成立性;而又有研究揭示开放系统并非总可热化。如何理解这些不相容的结论?围绕该问题,我们利用路径积分影响泛函方法研究了谐振子在有限温环境中趋于平衡的动力学,结果表明系统与环境形成的复合系统束缚态的形成与非马尔科夫效应对系统趋于平衡的热化行为具有本质的影响:在玻恩-马尔科夫近似下,系统将趋于唯一的与环境具有相同温度的正则热态(传统正则系综理论成立);而在非马尔科夫动力学下,当无束缚态时,系统仍可趋于一正则态,但其具有与环境完全不同的温度;而当束缚态形成时,系统的平衡态将不能用正则态描述。我们的研究结果既揭示了传统正则系综论成立的条件,又建立了平衡态统计物理与非平衡统计动力学的桥梁。我们的工作一方面有助于实验实现对微纳结构下物理系统的量子态操控,另一方面也为从非平衡动力学角度研究平衡态统计力学问题建立了微观基础。
[Abstract]:The micro nano structure is the size in the object structure between the molecular scale and micrometer. In quantum optics, as the micro electromagnetic mode structure in the space with local effect is very strong, it is light and matter of strong interaction and an important platform for state manipulation of quantum systems. In quantum information, micro nano structure in the all solid state properties become integrated single photon source and ideal carrier of information storage, conversion and transmission of photonic devices. In this paper, we master equation method based on open quantum systems, on the one side surface of plasma micro nano stable quantum entanglement between the structure of mechanical vibration in mesoscopic quantum dot resonance fluorescence and power system in the preparation, on the other hand, the establishment of conditions of regular thermalization equilibrium statistical mechanics is investigated in the method of nonequilibrium dynamics. First, we study on the layered surface plasmon The sub body micro nano quantum dot structure in the resonance driving power of the fluorescence emission spectrum and correlation statistics. In the traditional theory of atomic resonance fluorescence system developed mainly based on the dipole approximation, but we found that the intensity of quantum dots size expansion and surface plasma induced dramatic changes in space, four moments of quantum dots have significant influence on the fluorescence characteristics: on the one hand, the dipole approximation of quantum dots fluorescence spectrum rotation symmetry of quantum dots with space toward destruction, on the other hand, through the reasonable choice of the quantum dot orientation and four order moments, fluorescence spectrum can achieve the conversion between single peak and the peak of Mollow three structure; two order correlation function can be realized from the single photon weak radiation region transition to strong radiation area. We work on the use of quantum dots in quantum dot mesoscopic effect development as the carrier Has the meaning of single nano photonic devices. Secondly, based on the power system, we propose a library project through the preparation of stable quantum entanglement between two vibration mechanical oscillator in single cavity scheme. The thermal noise due to the existence of the macro mechanical system in basic could not observe the quantum coherence effect, power system provided by the pressure to reduce the ideal platform for mechanical oscillator, thermal vibration noise by using an optical and mechanical oscillator radiation, thus to quantum entanglement properties observed in macroscopic mechanical motion as possible. Unlike previous widely used scheme, we propose a new preparation method of double mirror vibration stability of quantum entanglement in a single cavity. Our scheme without resorting to pre cooling of the mechanical oscillator thermal vibration noise, the main use of the compression library engineering idea: we found that the cavity field into a broadband squeezed driving field Two, a mirror can obtain quantum entanglement stable. Analysis shows that the role of the media played in the mechanism from the cavity cavity: it will be from the broadband compression driver quantum field obtained compression transfer to the relative momentum of double mirror, which makes the double mirror steady show quantum entanglement of the collective quantum correlation characteristic. Our scheme provides a pre cooling scheme without stable entanglement preparation of mechanical motion system. Finally, the balance of the dynamics in finite temperature balance environment through the study of the quantum harmonic oscillator, we discussed the conditions of establishment of equilibrium statistical physics canomical thermalization from microcosmic point of view. On the basis of statistical physics knowledge of Physics from the micro perspective of ergodic hypothesis and the assessment of the scope of its establishment is the core problem in statistical physics. Previous studies found that any complex system of pure state will be accompanied by open system The regular heating, the results suggest that the establishment of regular heating and study; open system is not always intense. How to understand these inconsistent conclusions? Around this problem, we use dynamic path integral method to study the effects of functional oscillator balance in finite temperature, the results showed that the influence of nature thermalization behavior formation composite system and environment form bound states and non Markoff effect on the balance of the system: the Born Markoff approximation, the system will tend to be the only and the environment has regular hot temperature (the traditional canonical ensemble theory); while in non Markoff dynamics, when there is no bondage state, the system is still tends to be a regular state, but it is completely different from the temperature of the environment; and when the bound state is formed, the equilibrium state of the system will not be described by the regular state. The results of our study not only reveals the traditional system of regular conditions, and to build a bridge of equilibrium statistical physics and non equilibrium statistical dynamics. On the one hand our work contributes to the experimental realization of quantum state manipulation of micro nano structure of the physical system, on the other hand, as the micro foundation from non-equilibrium dynamics study of equilibrium statistical mechanics is established.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O413

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