带有三体相互作用的XXX自旋链模型的隐形传态

本文研究了基于一个带有多体相互作用（XZY-YZX型和XZX+YZY型）的三比特XXX海森堡自旋链模型的量子隐形传态. 首先求出该模型的本征值和本征态, 然后再以它在热平衡态下的纠缠为量子信道进行隐形传态并求出保真度的表达式. 分别分析了不带三体相互作用和仅带一种三体相互作用及同时带两种三体相互作用的XXX模型的保真度与外磁场和温度的关系, 得知仅带有XZX+YZY型三体相互作用的铁磁质海森堡XXX模型的隐形传态质量最好, 并且工作时需要的外界磁场最小、 温度相对较高, 在实验上容易实现.     

Entanglement properties between two atoms in the binomial optical field interacting with two entangled atoms

The temporal evolution of the degree of entanglement between two atoms in a system of the binomial optical field interacting with two arbitrary entangled atoms is investigated. The influence of the strength of the dipole–dipole interaction between two atoms, probabilities of the Bernoulli trial, and particle number of the binomial optical field on the temporal evolution of the atomic entanglement are discussed. The result shows that the two atoms are always in the entanglement state. Moreover, if and only if the two atoms are initially in the maximally entangled state, the entanglement evolution is not affected by the parameters, and the degree of entanglement is always kept as 1.     

Tavis-Cummings模型中两纠缠原子纠缠的演化特性

研究了两个纠缠的两能级原子与单模粒子数场进行相互作用系统中两原子的纠缠演化.结果表明：两个原子之间的纠缠呈现出周期性的演化特性，初始两原子的状态、原子之间的偶极相互作用和粒子数场对腔中两个原子的纠缠有着显著的影响.发现适当选择原子的初态，两原子会永远处于最大纠缠态. 关键词： 量子纠缠 偶极-偶极相互作用 部分转置矩阵负本征值 纠缠原子     

Nd-Fe-B永磁合金腐蚀产物的拉曼光谱研究

本文应用拉曼光谱法,研究了Nd—Fe—B永磁合金在NaCl,NaHSO_4水溶液及大气环境中的腐蚀产物组成及其变化。测定结果表明,Nd—Fe—B合金大气腐蚀产物的主要组成为:Nd(OH)_3,γ—FeOOH,α—FeOOH,Fe_3O_4及B_2O_3,在NaCl溶液中则有NdCl_3生成。在不同PH值的NaHSO_4溶液中,锈层的组成有所变化。据此,对Nd—Fe—B合金的腐蚀过程与机理进行了探讨。     

2007年江苏高考数学试卷分析

07江苏试题,进一步优化了结构,拓展了命题思路,起点较低,比较平稳,循序渐进,在全面考查基础的同时,突出体现对学生的数学基本功、数学应用、创新能力等方面的考查. 　　……     

Investigation of Kinematics of the Portevin-Le Chatelier Deformation Bands with Dynamic Digital Speckle Pattern Interferometry

The Portevin-Le Chatelier (PLC) effect with typical temporal instabilities in the recorded stress is closely associated with local inhomogeneities of deformation. By employing the dynamic digital speckle pattern interferometry technology, the characterizations for the PLC deformation bands of type A (continuous propagation along the specimen), type B (“hopping“ propagation along the specimen) and type C (random nucleation in the sample) were distinctly clarified. The corresponding positions of deformation bands were traced throughout the whole tensile process. By systemic experiments, the range of the applied strain rates for each type of bands existing was investigated respectively. The evolution of the band velocity (for types A and B) was also statistically investigated and qualitatively interpreted.     

声音传播实验的改进

现行课本上介绍的声音传播实验，要么使用抽气机，使瓶内气体变稀薄；要么使用烧瓶将水烧至沸腾，加盖冷却后使瓶内气体变稀薄．然后，由气体逐渐变稀，传出的声音逐渐减小进行推理，从而得出“声音在真空中不能传播”的结论．此类实验的不足之处是器材较多，实验的时