利用Bell态实现量子隐形传态

量子隐形传态利用了量子的纠缠特性,在物理层实现了不可破译的量子密码通信.文章从信息论的角度描述了量子纠缠态的特性,给出了实现量子纠缠态的物理门线路;利用该量子纠缠态的量子线路,分析隐形传态的通信模型,给出了利用Bell态实现隐形传态的简单结构的量子线路,证明该量子线路是可行的,为进一步研究量子密码通信提供参考.     

缺少一个数态的相干态

引入一种新的量子光场态／ａ，ｍ〉，它是是由相干态／ａ／〉去掉一个数态／ｍ〉后经归一化得到，研究了ｍ顺次取不同值时态／ａ，ｍ〉的各种量子统计性质，这相当于用一根探针在相干态内部顺次扫描数态观察各不同数态在决定相干态性质上所起的作用由此得到了一些很有意义的结果，其中特别是我们发现了这样一量子光场态－－它们表明反群聚与后松分布这两种非经典光即使在单模情况下也只是基本等价而不是完全等价。     

通过四比特 态实现任意量子态的量子隐形传态方案

提出了一个将四比特|χ〉态作为量子通道实现任意单量子比特和两量子比特的量子态的隐形传送方案.该方案依赖于两个通信站点之间的纠缠.在这个方案里,我们给出了Alice的测量结果以及Bob进行的相应的幺正操作,计算结果表明,该隐形传送方案是完美的,也就是说它的成功概率可达到1.此外,该方案中用到的测量以及纠缠通道的制备在目前的技术下是完全可行的.因此,我们的方案有望在实验上实现.     

未知EPR态及其正交态的概率复制

纠缠态在量子计算和量子信息中起着十分重要的作用。利用部分纠缠态作为资源提出了一种方案,根据该方案,能够以某些概率成功地复制出未知的EPR(Einstein Podolsky Rosen)态和它的正交态,使得通信双方都能够获得要传送的EPR态。方案的第一步是采用部分纠缠态作为量子信道去实现EPR态的隐形传态。根据量子不可克隆定理,输入态在发送方受到破坏。方案的第二步通过引入一个辅助量子位,发送者Alice在态的配制者Victor的帮助下,将以联合概率成功地获得未知EPR态和它的正交态。从而实现了量子态的重建。     

用一个纠缠态实现多粒子纠缠态的量子隐形传送

提出分别在二维和高维系统中利用一个纠缠态作量子通道实现M粒子纠缠态的量子隐形传送方案. 该方案有多个接收者,通过控制引进辅助粒子数,可以任意调节传送后的纠缠态在各接收者之间的粒子数分布, 且成功传送的概率为1. 关键词： 量子隐形传态 纠缠态 量子通道     

利用三粒子纠缠态建立量子隐形传态网络的探讨

利用W态纠缠源可以产生三纠缠粒子，用这些相互纠缠的粒子作为量子信道，再辅以经典信道传送Bell基联合测量信息和von Neumann测量信息，便可实现量子隐形传态网络.基于上述思想，研究了三纠缠粒子量子隐形传态网络的物理基础，得到了基于三粒子W 关键词： 量子通信 量子隐形传态 W态')" href="#">W态     

基于双模压缩信道的双模高斯态量子隐形传态

研究了双模高斯态的两个模经由两个双模压缩量子信道的隐形传态.结果表明，当输入态有纠缠时，若要输出态的纠缠不为零，量子信道的纠缠必须大于一确定值，其大小在输入态为纯态时依赖于输入态的纠缠度；在输入态为混合态时不仅与输入态的纠缠有关，还依赖于输入态的整体纯度. 关键词： 量子隐形传态 量子纠缠 双模高斯态     

四光子相干态是类虚化态

Ｓｒｉｎｉｖａｓａｎ和Ｌｅｅ从一个真实的量子辐射场的物理态和与之对应的非物理态的分布函数出发，引入了量子辐射场的虚化态（Ｒ．Ｓｒｉｎｉｖａｓａｎａｎｄ．Ｃ．Ｔ．ＬｅｅＰｈｙｓ．Ｌｅｔｔ．Ａ２１８（１９９６）１５１），接着，Ｄｅｌｉｍａ等人又真实的物理态出发引入了虚化态的概念，并表明奇偶相干态是一种类虚化态（Ａ．Ｆ．ｄｅｌｉｍａｅｔａｌ．Ｐｈｙｓ．Ｌｅｔｔ，Ａ２９９（１９９７）４１１）。本文证明量子     

利用GHZ态实现多原子缠结态的量子隐形传态

提出一种利用GHZ态实现多原子缠结态的量子隐形传态方案.当作为量子通道的GHZ态含有一个单模高Q腔时,大大地简化了量子稳形传态中的联合测量过程.     

利用五粒子簇态实现四粒子态的量子隐形传态

主要研究了运用五粒子簇态作为量子通道来实现特殊形式的四粒子态的量子隐形传态方案.该方案运用了量子力学中量子纠缠的理论.在这个方案中,发送者只需要进行五粒子冯·诺依曼投影测量,接收者根据发送者的测量结果,通过在其量子位上执行一些适当的幺正变换得出原始的四量子比特状态.提出的这个方案可以很好地应对一般的窃听方式.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.