纠缠光子空间关联调控及其应用

发布时间：2019-03-03 08:22

【摘要】：近年来,量子信息科学快速发展,展现出了诱人的应用前景。小型化集成化的量子光学芯片使得量子信息处理更加稳定,扩展性更强,成为了量子信息科学的一个新的发展方向。纠缠光子作为量子信息科学的一个重要物理资源,其产生与调控成为了重点的研究内容。而空间特性是纠缠光子基础且重要的一个调控维度。沿着量子信息科学的发展方向,更加集成化地产生和调控纠缠光子成了大势所趋。光学超晶格是最常用的一种产生纠缠光子的材料,利用灵活的畴工程技术,可以实现特殊性质纠缠光子的高效产生。本论文具体涉及以下几方面的研究内容：1、利用周期极化的钽酸锂晶体直接制备了具有横向动量正关联、位置反关联的反EPR纠缠态。理论计算了泵浦光聚焦参数对纠缠光子空间关联的调控特性。并实验上利用紧聚焦的泵浦光,在钽酸锂光学超晶格中制备了反EPR态。通过对其动量、位置不确定度的测量,计算出其动量位置不确定度乘积为(△X+)2(△p-)2=0.14±0.02h2,小于h2,从而验证了反EPR态的成功制备。2、通过理论计算,得到了不同动量关联特性下鬼成像分辨率和放大率的解析表达式。鬼成像的放大率由外部放大率和内禀放大率两部分组成,通过鬼成像实验测量得到内禀放大率可以用来作为纠缠度的判据。更重要的是,根据分辨率的表达式可以得到纠缠光子不同动量关联特性下,光路配置、晶体长度及泵浦光束腰对分辨率的影响。此外,我们给出了在不同配置参数下,鬼成像的数值模拟。这对于鬼成像的实验及其应用都具有指导性的意义。3、将经典光学中的菲涅尔波带片结构引入到了光学超晶格中。通过将钽酸锂晶体极化成波带片结构,制备了非线性菲涅尔波带片。并在实验上验证了这种非线性波带片可以同时实现二次谐波产生与成像。此外,我们将波带片结构引入到一维光学超晶格的横向调制上,通过理论计算发现,一个这样的结构等效为同时集成了均匀一维超晶格与具有多焦点的透镜。利用这种结构,可以实现多焦距的无透镜鬼成像,使得对纠缠双光子空间关联的调控更加便捷,集成化。4、基于量子纠错编码中的Shor码方案,我们提出了两种针对光子为量子信息载体的量子纠错方案。一种是编码在单光子多自由度上的量子纠错编码方案,利用这种方案,可以便捷地实现量子纠错,且大大降低了对光子数的要求。针对该方案,我们设计了完整的实验光路。此外,针对方案后续应用上可能存在的问题,我们提出了另一种编码在双光子多自由度上的量子纠错编码方案,该方案可以有效的解决差错检验时探测问题。这两个方案的提出,为光子为载体的量子纠错编码方案拓宽了思路。
[Abstract]:In recent years, quantum information science has developed rapidly, showing attractive application prospects. The miniaturization and integration of quantum optical chips makes quantum information processing more stable and expansible, which has become a new development direction of quantum information science. Entangled photons as an important physical resource of quantum information science, its generation and regulation has become the focus of research. Spatial properties are the basis of entanglement photons and an important regulatory dimension. Along with the development direction of quantum information science, more integrated generation and control of entangled photons has become the general trend. Optical superlattices are the most commonly used materials for the generation of entangled photons. The efficient generation of entangled photons with special properties can be achieved by using flexible domain engineering techniques. The main contents of this thesis are as follows: 1. The anti-EPR entangled states with transverse momentum positive correlation and position inverse correlation were prepared directly by using periodically polarized lithium tantalate crystals. The effects of pump light focusing parameters on the spatial correlation of entangled photons are calculated theoretically. An anti-EPR state was prepared in an optical superlattice of lithium tantalate using tightly focused pumping light. By measuring the momentum and position uncertainty, it is calculated that the product of momentum position uncertainty is (X) 2 (p -) 2 0. 14 卤0. 02 h 2, which is less than H 2, thus validating the successful preparation of anti-EPR states. 2. Through theoretical calculation, it is proved that the anti-EPR states have been prepared successfully. 2. The analytical expressions of resolution and magnification for ghost imaging with different momentum correlation characteristics are obtained. The magnification rate of ghost imaging consists of two parts: external magnification rate and intrinsic magnification rate. The intrinsic magnification rate can be used as a criterion for the degree of entanglement through the measurement of ghost imaging experiment. More importantly, according to the resolution expression, the effects of optical path configuration, crystal length and pump beam waist on the resolution of entangled photons are obtained under different momentum correlation characteristics of entangled photons. In addition, we give the numerical simulation of ghost imaging under different configuration parameters. This is instructive to the experiments and applications of ghost imaging. 3. The Fresnel zone plate structure in classical optics is introduced into the optical superlattice. The nonlinear Fresnel zone plates were prepared by polarizing lithium tantalate crystals into wave zone plates. The experimental results show that the nonlinear zone plate can generate and image the second harmonic simultaneously. In addition, we introduce the zone plate structure into the transverse modulation of one-dimensional optical superlattices. It is found by theoretical calculations that one of these structures is equivalent to a uniform one-dimensional superlattice and a lens with multi-focal points. With this structure, the multi-focal lens-free ghost imaging can be realized, which makes the control of entangled two-photon spatial correlation more convenient and integrated. 4, based on the Shor code scheme in quantum error correction coding, We propose two quantum error correction schemes for photons as quantum information carriers. One is a quantum error correction coding scheme encoded on a single photon with multiple degrees of freedom. With this scheme, quantum error correction can be realized conveniently, and the requirement of photon number is greatly reduced. For this scheme, we design a complete experimental optical path. In addition, aiming at the possible problems in the subsequent application of the scheme, we propose another quantum error correction coding scheme based on two-photon multi-degree-of-freedom coding, which can effectively solve the problem of error detection. These two schemes widen the idea of quantum error correction coding scheme based on photons.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O431.2

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