共查询到20条相似文献,搜索用时 187 毫秒
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《中国光学与应用光学文摘》2006,(3)
O431.2 2006031803利用谐振倍频产生纠缠光束=Experi mental generation ofentangled lights from resonating frequency doubler [刊,中]/罗玉(山西大学光电研究所,量子光学与光量子器件国家重点实验室.山西,太原(030006)) ,李莹…∥光学学报.—2006 ,26(2) .—305-309根据Anderson等人近期的理论研究,简要介绍了Ⅱ类相位匹配倍频过程产生纠缠光的理论计算过程,得出了纠缠的类型、纠缠度与抽运功率的函数关系和纠缠度的理论值。利用Ⅱ类非临界相位匹配的KTP晶体作为倍频晶体,采用倍频腔结构为半整块的单端驻波腔,在基频光波长获得了具有… 相似文献
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连续变量纠缠态由于其确定性产生、高效率的特点而被广泛应用于连续变量量子信息处理.在量子信息处理过程中纠缠态与量子信道发生相互作用而退相干,这是限制长距离量子信息发展的重要因素之一.光纤信道作为理想的量子信道,是目前连续变量量子信息研究关注的热点.本文利用Ⅱ类匹配的楔角极化磷酸氧钛钾晶体构成了三共振的非简并光学参量放大器,获得了8.3 dB的光通信波段1.5μm连续变量纠缠态光场.将产生的纠缠态光场注入单模光纤,其量子特性在传输距离达50 km后仍得到保持,纠缠度为0.21dB.该研究可为基于光纤的长距离连续变量量子信息研究提供有效的依据. 相似文献
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Time evolution law of a two-mode squeezed light field passing through twin diffusion channels 下载免费PDF全文
We explore the time evolution law of a two-mode squeezed light field(pure state)passing through twin diffusion channels,and we find that the final state is a squeezed chaotic light field(mixed state)with entanglement,which shows that even though the two channels are independent of each other,since the two modes of the initial state are entangled with each other,the final state remains entangled.Nevertheless,although the squeezing(entanglement)between the two modes is weakened after the diffusion,it is not completely removed.We also highlight the law of photon number evolution.In the calculation process used in this paper,we make full use of the summation method within the ordered product of operators and the generating function formula for two-variable Hermite polynomials. 相似文献
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量子纠缠是一种重要的量子资源,在多个空间分离的量子存储器间建立确定性的量子纠缠,然后在用户控制的时刻将所存储的量子纠缠转移到量子信道中进行信息的分发和传送,这对于实现量子信息网络是至关重要的.本文介绍了用光学参量放大器制备与铷原子D1吸收线对应的非经典光场,而且在三个空间分离的原子系综中确定性量子纠缠的产生、存储和转移.利用电磁感应透明光和原子相互作用的原理,将制备的多组分光场纠缠态模式映射到三个远距离的原子系综以建立原子自旋波之间的纠缠.然后,存储在原子系综中的纠缠态通过三个量子通道,纠缠态的量子噪声被转移到三束空间分离的正交纠缠光场.三束释放的光场间纠缠的存在验证了该系统具有保持多组分纠缠的能力.这个方案实现了三个量子节点间的纠缠,并且可以直接扩展到具有更多节点的量子网络,为未来实现大型量子网络通信奠定了基础. 相似文献
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高纠缠度的纠缠源是实现高保真度量子信息传输与处理的保障,因为受到光学元器件自身性能不完美的限制,通过有效的操控手段来提高光场的纠缠度是十分必要的.连续变量Einstein-Podolsky-Rosen纠缠态光场可以利用工作在阈值以下的非简并光学参量放大器来获得.将两个非简并光学参量放大器级联,可以利用第二个光学腔来操控第一个光学腔输出的纠缠态光场,在一定条件下实现光场的纠缠增强.本文通过理论分析设计出两种光学腔级联的实验系统,其中,纠缠产生装置采用具有三共振结构的半整块驻波腔,输出到目前为止世界上单腔获得两组份纠缠态光场纠缠度的最高值,操控光学腔采用驻波腔或四镜环形腔的结构.详细对比分析了不同结构的操控腔对纠缠增强效果的影响,得出利用不同腔形作为操控腔的最佳实验方案.同时分析了级联腔输出光场的纠缠度随不同物理参量的变化关系,得出进一步优化的最佳实验系统参量,为实验获得更高纠缠度的纠缠态光场提供了依据. 相似文献
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Eyob Alebachew Sete 《Optics Communications》2008,281(24):6124-6129
We show that a two-mode three-level cascade laser driven by external coherent fields generate intense entangled light. It turns out that external driving fields which are at resonance with the cavity modes substantially improve the intensity of the two-mode light in the cavity in a region where the squeezing and entanglement is significant making the system under consideration a viable source of bright squeezed as well as entangled light. 相似文献
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Two amplification schemes are considered for entangled squeezed states of light, including an Einstein-Podolsky-Rosen entangled state of continuous variables (EPR pair): propagation in a nonlinear medium and reflection from a cavity. Both schemes make use of a parametric process that can be implemented in a periodic nonlinear medium. The existence of an integral of motion makes it possible to amplify an entangled state of light while preserving the initial entanglement. To analyze the cavity-based scheme, a master equation is derived for the density matrix of the field inside the cavity. The feasibility of amplification that preserves entanglement of an EPR pair is demonstrated for this scheme. 相似文献
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Preparation of entangled squeezed states and quantification of their entanglement 总被引:3,自引:0,他引:3 下载免费PDF全文
We propose a scheme for generating bipartite and multipartite entangled squeezed states via the Jaynes-Cummings model with large detuning. Bipartite entanglement of these entangled states is quantified by the concurrence. We also use the N-tangle to compute multipartite entanglement of these multipartite entangled squeezed states. Finally we discuss two limiting cases which arise from r→∞ and r→0, in which the multipartite entangled squeezed state reduces correspondingly into an N-qubit Greenberger-Horne-Zeilinger state and an N-qubit W state. 相似文献
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Chang-Yong Chen 《International Journal of Theoretical Physics》2008,47(5):1397-1408
A scheme has been proposed for generating the macroscopic superpositions and the entanglement between the mesoscopic squeezed
vacuum states by considering the two-photon interaction of N two-level atoms in a dissipative cavity with high quality factor assisted by a strong driving field. A number of multiparty
entangled states between the atoms and the squeezed vacuum states, among the atoms, and among the squeezed vacuum states,
can be prepared by virtue of a specific choice of the cavity detuning and the detuning of applied coherent field under the
dissipation condition. The corresponding analytical expressions of the influence can be given. Moreover, we can also give
a series of macroscopic entangled states between the usual coherent states and the squeezed vacuum states using the combination
of the dissipative one-photon interaction Hamiltonian with the dissipative two-photon interaction Hamiltonian. We also discuss
the experimental feasibility. Our scheme can be realized in the current techniques on the cavity QED. 相似文献