Separability Criteria for Quantum Mixed States in Terms of Trace Norm

A new necessary conditions for separability of mixed states in bipartite and multipartite quantum systems of arbitrary dimensions are presented. This method requires only a few local measurements. If a quantum state in a bipartite （or multipartite） system of arbitrary dimension is separable, we show that the trace norm of a constructive matrix is less than or equal to 1.     

LP-MOCVD生长(ZnCdTe,ZnSeTe)/ZnTe复合量子阱的激子发光研究

用低压金属有机化学气相沉积(LP-MOCVD)的方法在GaAs(100)衬底上生长了(ZnCdTe，ZnSeTe)／ZnTe复合量子阱结构。测量了生长样品的光致发光(PL)谱，得到两个发光峰(记为Il，I2)，分析认为高能侧的峰为Zn0．9Cd0．1Te浅阱峰，而低能侧的峰为ZnSe0．2Te0.8深阱层的发射。对样品进行了变激发强度的PL谱测量，当激发强度增加时，PL谱中两个发光峰的比值(I2／I1)开始时迅速增加，然后缓慢减小。这是由于浅阱中的电子和空穴隧穿入深阱中导致空间电荷的分离，从而在复合量子阱结构中产生了一个内建电场所引起的。     

量子点系统的热力学稳定性及其单粒子分布函数的单调性质：零温时的情况

利用一个量子点体系中基态的稳定性和变分原理,证明了在零温时,该体系的单粒子分布函数对于量子点上单粒子能级而言是非增的.这一结果表明,一个量子多体体系中谱函数的行为在很大程度上是由其热力学稳定性条件决定的.     

我国住房抵押贷款提前还款影响因素分析

提前还款问题是住房抵押贷款证券要解决的一个基本问题.在介绍国外有关提前还款行为影响因素的基础上,针对我国的具体情况,用灰色关联法分析我国提前还款行为的影响因素.     

1．55μmInGaAsP及其相应量子阱结构的LP－MOCVD生长

本文研究了用低压金属有机化合物汽相外延（ＬＰ－ＭＯＣＶＤ）技术在（１００）ＩｎＰ衬底上生长ＩｎＧａＡｓｐ体材料及ＩｎＧａＡＰ／ＩｎＰ量子阱结构材料的生长条件。三甲基镓（ＴＭ６３）、三甲基铟（ＴＭｈ）和纯的砷烷（Ａ８Ｈ３）、磷烷（ＰＨ３）分别用作Ⅲ族和Ⅴ族源，在非故意掺杂情况下，ＩｎＧａＡｓＰ材料的载流子浓度为３．６×１０１５ｃｍ－３；在液氦温度和室温下，与ＩｎＰ晶格匹配的ＩｎＧａＡｓＰ光致发光半峰宽分别为１９．２ｍｅＶ和６３ｍｅＶ；对外延层的组分及厚度均匀性分别进行了转靶Ｘ光衍射仪，低温光致发光和扫描电子显微镜分析，对不同阱宽的量子阱结构材料测出了由于量子尺寸效应导致光致发光波长随阱宽增加而红移现象。     

Rabi Oscillations in Two－Component Bose－Einstein COndensates with a Coupling Drive

The Rabi oscillations in two-component Bose-Einstein condensates with a coupling drive are studied by means of a pair of bosonic operators.The coupling drive and initial phase difference will affect the amplitude and the period of the Rabi oscillations.The Rabi oscillations will vanish in the evolution of the condensate density for some special initial phase differences(φ=0 or π).Our theory provides not only an analytical framework for quantitiative predictions for two-component condensates,but also gives an intuitive understanding of some mysterious features observed in experiments and numerical simulations.     

闭模糊n级正关联理想

引入闭模糊n级正关联理想 ，刻划其结构和性质。     

嵌入耦合量子点的介观Aharonov-Bohm环内的持续电流

使用双杂质的Anderson模型的哈密顿量，从理论上研究了一个嵌入耦合量子点的介观Aharonov-Bohm环系统处在Kondo区时的基态性质, 并用slave-boson平均场方法求解了哈密顿量. 结果表明, 在这个系统中, 宇称效应和复杂的电流 相位关系的出现反映了两个量子点可以相干耦合. 关键词： 持续电流 耦合量子点 宇称效应 Kondo效应     

Increasing the Efficiencies of Random-Choice-Based Quantum Communication Protocols with Delayed Measurement

The security of quantum communications lies in the capability of the legitimate parties to detect eavesdropping.Here we propose to use delayed measurement to increase the efficiency of protocols of quantum key distribution and quantum secret sharing that uses a random choice of measuring-basis. In addition to a higher efficiency,these measures also bring the benefit of much reduced amount of classical communications.