Entanglement, interference, and measurement in a degenerate parametric oscillator

Quantum dynamical equations of motion for homodyne detection of the degenerate optical parametric oscillator are solved exactly. Nonclassical photon statistics are shown to be a consequence of interference of probability amplitudes, entanglement of photon pairs from such an oscillator, and the role of measurement in quantum evolution.     

Laser-diode-pumped Cr(4)+, Nd(3)+:YAG with self-Q-switched laser output of 1.4 W

By use of a laser diode as a pump source, a self-Q-switched laser from a Cr, Nd:YAG crystal is demonstrated. The output Q-switched traces are very stable, the threshold pump power is 3.5 W, the pulse duration is 50 ns, and the slope efficiency is as high as 20%. In addition, the pulse width remains constant while the pulse repetition rate varies with pump power.     

Spin-locking mechanism of spin I = 3/2 quadrupolar nuclei undergo magic angle spinning

The spin-locking mechanism of the spin I=3/2 quadrupolar nuclei under magic angle spinning (MAS) has been theoretically and experimentally investigated, and the criterion of adiabatic passage around zero-crossings of the quadrupole splitting was inferred from the time-dependent Shrödinger equation in this article. The theory, numerical simulations, and experiments conducted in this work all indicated that second-order quadrupole interaction and off-resonance play important roles in the spin-locking of the quadrupolar nuclei, and they were responsible for the great loss of the spin-locking signals. The spin-locking for a spin I=3/2 nucleus might be achieved by minimizing the effect of the second-order quadrupole interaction by using a radio frequency (RF) offset. This offset was realized by setting the RF to the opposite position of the isotropic second-order quadrupolar shift of single quantum coherences.     

用晶格玻尔兹曼方法研究螺旋波的产生机制和演化行为

采用五速正方晶格玻尔兹曼模型，由晶格玻尔兹曼方程推导得到了反应扩散方程.分析了Selkov反应扩散系统螺旋波的形成机制.零流边界条件下计算机数值模拟螺旋波的形成和破碎过程，发现Selkov反应扩散系统的失稳属于Doppler失稳.改变参数模拟系统的演化行为，发现不同的参数下系统可能到达三种不同的状态：均匀定态、混沌状态和螺旋波. 关键词： 晶格玻尔兹曼方法 螺旋波 计算机模拟     

含氮氟化类金刚石(FN-DLC)薄膜的研究：(Ⅳ)氮掺杂对薄膜结构的影响

不同条件下，在单晶硅基片上沉积了含氮氟化类金刚石(FN-DLC)薄膜.原子力显微(AFM)形貌显示，掺N后，薄膜变得致密均匀.傅里叶变换吸收红外光谱(FTIR)表明，随着r(r=N₂/［N₂+CF₄+CH₄］)的增大薄膜中C—H键的逐渐减少，C〖FY=,1〗N和C≡N键含量逐渐增加.X射线光电子能谱(XPS)的C1s和N1s峰拟合结果发现，N掺入导致在薄膜中出现β-C₃N₄和a-CN_x(x=1,2,3)成分.Roman散射谱的G峰向高频方向位移和峰值展宽等证明：随着r的增大，薄膜内sp²键态含量增加. 关键词： 氟化类金刚石膜 键结构 氮掺杂     

Yb∶Y_3Al_5O_(12)晶体晶格振动光谱的研究

采用提拉法生长Y3Al5O12(YAG)晶体和Yb3 掺杂原子数分数分别为5%,10%,15%,20%,25%,50%和100%的Yb∶Y3Al5O12(Yb∶YAG)晶体。系统表征和分析了Yb3 掺杂浓度对拉曼光谱的影响。随着Yb3 掺杂浓度的增加,晶体的振动模式没有明显的变化,晶体结构没有改变;在370 cm-1和785 cm-1附近,振动吸收峰的半峰全宽逐渐增大。分析得出,Yb3 掺杂浓度对晶体的晶格、对称性、荧光寿命均有影响,从而可能影响到晶体的光谱和激光性能。     

SiO2分子的基态(X1A1)结构与分析势能函数

应用群论及原子分子反应静力学方法推导了SiO2分子的电子态及其离解极限,采用B3P86方法,在6-311G**水平上,优化出SiO2基态分子稳定构型为单重态的C2V构型,其平衡核间距Re=RSi-O=0.1587 nm,∠OSiO=111.2°,能量为-440.4392 a.u..同时计算出基态的简正振动频率:对称伸缩振动频率v(B2)=945.4cm-1,弯曲振动频率v(A1)=273.5 cm-1和反对称伸缩振动频率v(A1)=1362.9cm-1.在此基础上,使用多体项展式理论方法,导出了基态SiO2分子的全空间解析势能函数,该势能函数准确再现了SiO2(C2V)平衡结构.     

非简并四波混频体系中双模光场的纠缠特性

利用非简并四波混频体系制备出稳定的连续变量的纠缠态，研究了纠缠随时间的演化情况.同时，得到双模光场的特征函数.经分析可知，在强抽运光的作用下此体系相当于一个光学参量放大器；在满足一定的条件下，能够制备出稳定的连续变量的量子纠缠态，并且纠缠的程度与双光子抽运光强度、合作参量及失谐频率有关. 关键词： 连续变量 三能级 高斯态 参量放大器     

试论汉字教学与提高语文素养的关系

汉字教学在语文教学中是一块"鸡肋",存在着许多问题,有必要全面提升汉字教学的系统性和可操作性。本文试图从汉字本身的规律及其延伸拓展的作用方面,探讨汉字教学与语文素养之间的关系,进而促进汉字教学的发展。     

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