红外单光子探测器定标方法研究

紫外激光器输出的355 nm激光泵浦BBO晶体,采用晶体的I类相位匹配,利用晶体的角度调谐特性得到的红外波段光源应用于单光子探测器定标,提出了利用参量下转换产生的纠缠光子对定标SPCM单光子探测器量子效率的方法,介绍了实验原理和定标装置。     

基于波段可调关联光子源的量子效率测量系统研究

随着单光子探测器应用领域的拓展,其覆盖波段不断增加,为满足不同波段探测器量子效率定标的需求,研究基于波段可调关联光子源的量子效率测量系统意义重大。设计了角度相位匹配的波段可调关联光子源,计算了多波段晶体的相位匹配曲线,搭建了光源系统及符合测量平台。测量了参考通道和符合通道的光子数,分析实验数据,完成了信号光通道探测器量子效率的测量。单光子探测器在1550 nm波段的量子效率为9.42%,与出厂数据在相应波长处量子效率偏差为0.58%,验证了方法的可行性,为进一步发展高精度的多波段量子效率测量系统奠定了基础。     

PPKTP晶体相位匹配关系分析

压缩态光场和纠缠态光场等非经典光场是进行量子信息研究的基本资源,其中压缩态光场在低于量子噪声极限的量子精密测量中有着重要应用,而纠缠态光场被广泛应用于量子隐形传态,量子计算等领域。利用由不同类型相位匹配的非线性晶体构成的光学参量振荡器是制备不同类型非经典光场的有效手段之一。文章通过分析Ⅱ类周期极化磷酸氧钛钾(periodically poled KTiOPO_4,PPKTP)的准相位匹配条件,发现在改变其抽运光及注入种子光偏振的情况下,利用一种晶体可以分别实现两种类型的相位匹配,从而可以制备两种不同类型的非经典光场。理论预测的结果与已得到的实验数据基本一致。     

周期极化波导与铁电畴反转机理研究综述

通过分析晶体材料的双折射相位匹配与准相位匹配条件,总结了实现准相位匹配的铁电畴周期反转技术,并就铁电畴反转检测方法、铁电畴反转机理进行详细探讨,指出通过波导技术与周期极化相结合,可以有效提高材料的非线性效应。针对离子交换制备周期极化波导的铁电畴反转深度与波导深度不一致的问题,提出采用离子注入损伤层对周期极化波导进行调控的新思路。     

PPLN-OPO非线性变频特性的研究

根据准相位匹配和光参量振荡原理，分析了光学超晶格材料PPLN实现参量过程时极化周期、匹配温度和调谐波长之间的关系，提出了同时使用周期调谐和温度调谐实现大范围波长调谐的调谐方法，并对PPLN-OPO在不同泵浦波段的周期调谐特性和温度调谐特性进行了研究．     

啁啾纠缠光子对的产生与压缩研究进展

利用连续激光泵浦啁啾准相位匹配的非线性晶体(或波导),通过自发参量下转换过程可以产生超宽带频谱的纠缠光子对,称为啁啾纠缠光子对。由于其具有超宽带频谱特性因而被广泛应用于高精度量子光学相干层析、宽带量子信息处理等多个领域。但由于同时产生频率二次相位因子,导致双光子关联时间被拓宽,从而制约其在量子度量衡、量子平板印刷术及量子时钟同步等相关领域的应用,因此需要对其关联时间进行压缩,而压缩的关键是要实现相位补偿。综述啁啾纠缠光子对的产生方法和压缩方法及相关的理论和实验研究进展,对不同的压缩方法进行比较分析并总结各自的优缺点。     

基于掺氧化镁周期性极化铌酸锂的光学参量产生器

报道了基于掺氧化镁的周期性极化铌酸锂（PPMgLN）光学参量产生器的研究。采用1064nm声光调Q准连续Nd：YAG激光器作为泵浦源,重复频率为4．3kHz。光学参量晶体PPMgLN的周期为30．7μm。采用温度调谐,调谐的范围为30℃～180℃,输出信号光的调谐范围为1561nm～1672nm,最高输出功率为180mW,相应的1064nm光的泵浦功率为1．017W,光光转换效率为17．7％。     

非对称偏振三维纠缠态的预警制备

在量子信息处理过程中,量子纠缠态扮演着极为重要的角色,其特殊的物理性质,使得量子信息具有经典信息所没有的许多新的特征,为信息传输和信息处理提供了新的物理资源.针对非对称偏振三维纠缠态的制备,基于交叉相位调制技术,以纠缠光子对和两个单光子比特作为初态,通过单光子与相干光的相互作用以及双光子干涉来实现.如果通过三个非计数单光子探测器来预警制备三维最大纠缠态,其概率为3/64.而如果采用特殊的分段式光子探测器,其概率可以提高到3/8,达到理论极限值.该方案在理论上是可行的,效率相对较高,而且预警式的制备为其后续在量子信息过程中的使用提供了很大的灵活性.     

同频率纠缠双光子态的量子相干特性

基于量子相干原理,分析了脉冲激光泵浦的第二类型自发参量下转换产生的同频率纠缠双光子态.研究了同频率纠缠双光子的量子相干性质,并与由脉冲激光所产生的不同频率纠缠双光子的量子相干性质做了对比.结果表明,随着激光脉冲宽度的增加,不同频率纠缠双光子态的相位匹配函数的不对称性增加,纠缠光子对的相干性减小,同频率纠缠双光子态的相位匹配函数仍保持对称,纠缠光子对的相干性达到最大.     

KBe_2BO_3F_2的晶体角度调谐

基于三波耦合的能量、动量守恒条件和KBe2BO3F2(KBBF)晶体最新的色散方程,研究了共线Ⅰ类、Ⅱ类相位匹配和非共线Ⅰ类相位匹配KBBF晶体的角度调谐曲线;并比较了共线相位匹配和非共线相位匹配的特点.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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