共查询到19条相似文献,搜索用时 671 毫秒
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自发参量下转换对应于一种非线性光学过程, 实验上作为一种标准方法, 人们利用自发参量下转换源产生纠缠光子对. 本文考虑由自发参量下转换源产生三对纠缠光子的情况. 通过使用由几组偏振光 束分束器、分束器和半波片等线性光学器件组成的量子线路演化三对光子, 给出了一个高效制备 包含偏振纠缠和空间纠缠的六光子超纠缠态方案. 因为方案中包含了参量下转换源产生三对纠缠光子 的所有可能情况, 所以本方案有很高的效率. 基于弱非线性介质构建了一个量子非破坏性测量装置, 用于区分光子在两指定的空间模中的两种分布情况. 特别地, 方案中可以通过合理约束在量子非破坏性测量过程中引入的非线性强度来达到实际实验所限定的数量级, 因此, 该方案易于在实验上实现. 相似文献
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研究了两个初始处于纠缠相干态上的宏观场各自独立地与一个环境相互作用的系统, 环境对腔场的影响只体现在腔场光子数的泄漏上. 采用共生纠缠(concurrence)度量两个宏观场间的纠缠, 并给出宏观场纠缠的解析解, 以分析这种系统中宏观场纠缠的动力学特性. 研究表明当场的初始平均光子数较大时, 即使很小的光子泄漏率也会导致腔场间出现纠缠突然死亡现象. 同时研究结果也表明光子从腔场泄漏到环境后会导致两环境间的纠缠突然产生, 而这种纠缠产生的时机直接与腔场的初始光子数相关. 本文还进一步发现在大光子数的情况下, 在任何时刻任意一个腔场与任意一个环境间都不会产生纠缠.
关键词:
纠缠相干态
环境
纠缠突然死亡
纠缠突然产生 相似文献
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探索制备纠缠光子对的新途径是量子光学领域的一个研究热点.从理论上证明在准周期极化 的光学超晶格晶体中的级联参量过程能够产生纠缠光子对.分别利用脉冲和连续的532nm抽运 光在一块准周期极化的 LiTaO3晶体中同时实现非简并参量下转换(产生信号光与闲置光 )与和频(闲置光与抽运光和频生成和频光)的级联参量过程,获得630nm的信号光与460nm 的和频光.指出信号光与和频光之间存在纠缠关联性质.该方案的优点是可产生短波长的纠缠 光子对.
关键词:
准相位匹配
级联参量过程
光量子纠缠态 相似文献
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提出了一种基于N个有序纠缠光子对量子机密共享方案.用纠缠光子作为信息的载体,密钥管理者Alice将纠缠光子对分成两个序列,其中一个序列直接发送给合作者之一Bob,在确保第一个序列发送安全后,再对第二个序列进行编码,发送给另一个合作者Charlie.Bob和Charlie分别对他们所接收到的光子序列进行Bell基联合测量,从而得到Alice所发布的密钥,完整密钥的获得需要管理者和所有合作者共同实现.本方案采用两体纠缠态,相对三体纠缠态来说,在实验上更容易实现,仅需要线性光学元件和简单的纠缠源. 相似文献
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We report a scheme for generating pulsed polarization-entangled photon pairs based on conversion from time-bin entanglement to polarization entanglement by use of an orthogonal polarization delay circuit and post-selection. We have experimentally demonstrated the scheme, using a periodically poled lithium niobate waveguide, and successfully obtained polarization entanglement in the 1.55-microm telecom wavelength band. 相似文献
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Spontaneous four wave mixing in nonlinear waveguide is one of the excellent technique for generating photon pairs in well-defined guided modes. Here we present a comprehensive study of the frequency characteristic of correlated photon pairs generated in telecom C-band from a dispersion-engineered silicon wire waveguide. We have demonstrated that the waveguide configuration, shape of pump pulse, two-photon absorption as well as linear losses have significant influences on the biphoton spectral characteristics and the amount of frequency entanglement generated. The superior performance as well as the structural compactness and CMOS compatibility makes the silicon wire waveguide an ideal integrated platform for the implementation of on-chip quantum technologies. 相似文献
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《理论物理通讯》2015,(12)
Spontaneous four wave mixing in nonlinear waveguide is one of the excellent technique for generating photon pairs in well-defined guided modes. Here we present a comprehensive study of the frequency characteristic of correlated photon pairs generated in telecom C-band from a dispersion-engineered silicon wire waveguide. We have demonstrated that the waveguide configuration,shape of pump pulse,two-photon absorption as well as linear losses have significant influences on the biphoton spectral characteristics and the amount of frequency entanglement generated. The superior performance as well as the structural compactness and CMOS compatibility makes the silicon wire waveguide an ideal integrated platform for the implementation of on-chip quantum technologies. 相似文献
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利用高非线性光纤产生量子关联光子对的实验研究 总被引:2,自引:2,他引:0
光纤中基于三阶(克尔)非线性效应的自发四波混频是制备量子关联光子对的有效方法之一。若采用商售高非线性光纤作为产生光子对的非线性介质,则有利于减小所需光纤的长度,从而缩小实验装置体积并降低对于抽运源的要求。利用脉冲光抽运20m的高非线性光纤产生通讯波段的频率近简并关联光子对,研究了光纤的弱双折射特性对于光子对产生的影响。当抽运光沿高非线性光纤的偏振轴入射时,具有最大的光子对产生效率,且光子对绝大部分与抽运光偏振平行;抽运光沿与光纤偏振轴45°入射时,光子对的产生效率最小,约为最大值的80%。 相似文献
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Photonic Crystal Fiber Source of Quantum Correlated Photon Pairs in the 1550nm Telecom Band
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A source of quantum correlated photon pairs in the 155Onto telecom band obtained by a pumping 11 m photonic crystal fiber with lOps pulse trains is experimentally demonstrated. We investigate how the birefringence of the fiber influences the purity of the photon pairs. We also present the frequency correlation of the signal and idler photon pairs. The experimental results are useful for developing a compact source of photon pairs well suited for quantum communication. 相似文献
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Xiong C Monat C Clark AS Grillet C Marshall GD Steel MJ Li J O'Faolain L Krauss TF Rarity JG Eggleton BJ 《Optics letters》2011,36(17):3413-3415
We report the generation of correlated photon pairs in the telecom C-band at room temperature from a dispersion-engineered silicon photonic crystal waveguide. The spontaneous four-wave mixing process producing the photon pairs is enhanced by slow-light propagation enabling an active device length of less than 100?μm. With a coincidence to accidental ratio of 12.8 at a pair generation rate of 0.006 per pulse, this ultracompact photon pair source paves the way toward scalable quantum information processing realized on-chip. 相似文献
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Xiaoxin Ma 《Optics Communications》2011,284(19):4558-4562
Correlated signal and idler photon pairs with small detuning in the telecom band can be generated through spontaneous four-wave mixing in dispersion shift fibers. However, photons originated from other nonlinear processes in optical fibers, such as Raman scattering and self-phase modulation, may contaminate the photon pairs. It has been proved that photons produced by Raman scattering are the background noise of photon pairs. Here we show that photons induced by self-phase modulation of pump pulses are another origin of background noise. After studying the dependence of self-phase modulation induced photons in signal and idler bands, we demonstrate that the quantum correlation of photon pairs can be degraded by the self-phase modulation effect. The investigations are useful for characterizing and optimizing an all fiber source of photon pairs. 相似文献
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自发参量下转换过程制备的纠缠光源在量子光学及其相关领域有着广泛的应用.本文利用780 nm的分布式布拉格反射镜激光二极管抽运一块长10 mm的Ⅱ类准相位匹配的周期极化铌酸锂波导,产生了偏振正交的频率反关联纠缠光子对.通过实验结果与理论的完美结合得到,当进入波导的抽运光功率为44.9 mW时,下转换双光子对的产生速率为1.87×10~7s~(-1).利用单色仪对下转换光子的频谱进行分析,得到信号和闲置光子的中心波长分别为1561.43 nm和1561.45 nm,频谱宽度为3.62 nm和3.60 nm,双光子符合包络宽度约为3.18 nm,可以得到双光子的频率纠缠度为1.131.00,表征了双光子的频率纠缠特性.利用Hong-Ou-Mandel干涉仪测量双光子的二阶量子干涉特性,测得的干涉可见度为96.1%,干涉图谱的凹陷宽度为1.47 ps. 相似文献
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We report the realization of a bright ultrafast type II parametric down-conversion source of twin beams free of any spatiotemporal correlations in a periodically poled KTiOPO4 (PP-KTP) waveguide. From a robust, single-pass setup it emits pulsed two-mode squeezed vacuum states: photon-number entangled pairs of single-mode pulses or, in terms of continuous variables quantum optics, pulsed Einstein-Podolsky-Rosen states in the telecom wavelength regime. We verify the single-mode character of our source by measuring Glauber correlation functions g(2) and demonstrate with a pump energy as low as 75 pJ per pump pulse a mean photon number of 2.5. 相似文献