Effect of Fermion Velocity on Phase Structure of QED3

Dynamical chiral symmetry breaking (DCSB) in thermal QED₃ with fermion velocity is studied in the framework of Dyson-Schwinger equations. By adopting instantaneous approximation and neglecting the transverse component of gauge boson propagator at finite temperature, we numerically solve the fermion self-energy equation in the rainbow approximation. It is found that both DCSB and fermion chiral condensate are suppressed by fermion velocity. Moreover, the critical temperature decreases as fermion velocity increases.     

有限温度真空极化与热背景介质的电磁性质

用有限温度场论方法,研究了真空极化的温度和密度效应及背景介质的电磁性质,严格计算了真空极化的有限温度、密度修正和热背景介质的介电常数与磁导率,给出了对任何温度和任何密度都适用的严格的解析表达式.     

手征对称性动力学破缺和铜氧化物超导体相变的三维量子电动力学研究

利用三维量子电动力学理论中的Dyson-Schwinger方程方法, 研究了零温情况下平面铜氧化合物超导体的反铁磁相和d波超导相之间的相变. 通过在朗道规范下近似解析求解和数值求解完全耦合的Dyson-Schwinger方程、并将所得结果与1/N展开方法的结果相比较, 发现在半填充准费密子味道数约小于等于4的情况下, 通过手征对称性自发破缺, d波超导相可以演化到反铁磁相, 并且反铁磁相有可能与d波超导相共存. 通过进一步比较不同相的压强, 还说明反铁磁与d波超导共存相为稳定相, 从而反铁磁相确实可以与d波超导相共存.     

Critical Number of Fermion Flavors at Finite Chemical Potential in QED3

We propose a new method for calculating the dressed fermion propagator at finite chemical potential in QED3 under the rainbow approximation of Dyson-Schwinger equation. In the above approximation, we show that the dressed fermion propagator at finite chemical potential # has the form S（p） = iγ.p^-A（p^-2） ＋ B（ p^-2） with p^-μ= （p^-1p3 ＋ iμ）. Using this form of fermion propagator at nonzero chemical potential, we investigate the Dyson-Schwinger equation for the dressed fermion propagator at finite chemical potential and study the effects of the chemical potential on the critical number of the fermion flavors.     

Critical Number of Fermion Flavors at Finite Chemical Potential in QED3

We propose a new method for calculating the dressed fermion propagator at finite chemical potential in QED3 under the rainbow approximation of Dyson-Schwinger equation. In the above approximation, we show that the dressed fermion propagator at finite chemical potentialμ has the form S (p) = iγ. pA (p2) B (p2) with pμ = (p, p3 iμ).Using this form of fermion propagator at nonzero chemical potential, we investigate the Dyson-Schwinger equation for the dressed fermion propagator at finite chemical potential and study the effects of the chemical potential on the critical number of the fermion flavors.     

不同调制方式下偏振度与偏振模色散的关系

给出了偏振度与偏振模色散关系的理论模型,分析了非归零和归零两种调制方式下的偏振度与偏振模色散关系特性,结果表明偏振度町以作为实时检测偏振模色散的信号;且偏振度对偏振模色散的有效检测范围不大于调制光信号的占空比α,同时检测灵敏度与有效检测范围成反比;在非归零调制时偏振度对偏振模色散的有效检测范围最宽,为调制光信号的一个调制周期,是常规归零调制(占空比为0．5)时的2倍,但灵敏度只有常规归零调制时的一半。进一步探讨了在实际应用中改善偏振度对偏振模色散的有效检测范围和灵敏度的方法。实验验证了非归零调制时偏振度与偏振模色散关系特性。     

Phase Matching Property of Cross Polarization Four Wave Mixing in BaTiO3 Crystal

Four wave mixing (FWM) is of considerable interest in generation of a phase conjugate beam with photorefractive crystals. The common methods of FWM are parallel polarization FWM and cross polarization FWM. In this paper, we analyze the phase matching property of the latter. First, we consider the phase matching condition, and derive equations representing the angler relationship of interacting beams. Then, we consider the phase mismatching which is caused by shift of the probe beam angle from the phase matching condition, and calculate the effect of the shift of this angle on the amount of phase mismatching. We also determine and closely examine the coupling constant.     

不同调制格式的偏振模色散补偿性能分析

研究了不同调制格式的产生及其偏振模色散补偿性能。首先从实验上得到了不同调制格式的频谱和眼图,并将其输入偏振模色散补偿系统,实现了缓解与补偿的动态结合。其次,从数值上比较和分析了不同调制格式应用于以偏振度做反馈信号的偏振模色散补偿系统后的补偿性能,结果表明,差分相移键控对偏振度的响应度和偏振模色散补偿效果要比传统开关键控好,因此差分相移键控非常适合于以偏振度做反馈信号的偏振模色散补偿系统;而载波抑制码差分相移键控结合了载波抑制码载波抑制特性和差分相移键控的特殊频谱特性,具有最好的偏振模色散补偿效果。     

Polarization and phase control of two-photon absorption in an isotropic molecular system

<正>We theoretically and experimentally study the polarization and phase control of two-photon absorption in an isotropic molecular system.We theoretically show that the two-photon transition probability decreases when the laser polarization changes from linear through elliptical to circular,and the laser polarization does not affect the control efficiency of two-photon transition probability by shaping the spectral phase.These theoretical results are experimentally confirmed in coumarin 480.Furthermore,we propose that the combination of the laser polarization with the spectral phase modulation can further increase the control efficiency of the two-photon absorption.     

阶跃光纤低阶线偏振模的M2因子分析

针对阶跃光纤输出低阶线偏振模（Linear Polarization,LP）,利用二阶距定束宽,多点拟合法计算了几个低阶LP mn模相干和非相干叠加时的M2因子.结果表明,对同一LP mn模式,光纤的归一化频率参量V减小到截止频率时,M2因子出现峰值;当V远离截止频率时M2因子趋于一定值.低阶LP mn模非相干叠加时,叠加后的较高阶模成分越大,合成光束的光束质量越差,光束在一定的条件下可能比基模更接近于理想高斯光束;而相干叠加时,合成后的M2因子可以大于参与叠加的较高阶模的光束质量因子.     

Phase Correlations and Polarization Characteristics of Dye-Solution Laser Radiation

The influence of phase correlations of components on the energy and polarization parameters of output radiation have been calculated within the framework of the formalism of polarization components. It is shown that these correlations have a marked effect only on the energy characteristics. At the same time, an analysis of the polarization characteristics of a probe wave provides rich information for the analysis of the phase-polarization structure of radiation. An analysis of experimental data allows the inference that the correlation of components is relatively weak even for lasers with a high-Q resonator and at a high excess of threshold values. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 591–597, September–October, 2005.     

布儒斯特角切割LiNbO3晶体的偏振态分析

基于琼斯矩阵和菲涅耳公式,建立了偏振光透过LiNbO3晶体的分析模型,研究了入射光偏振态、晶压等参数对输出光偏振态和p偏振态、s偏振态透射率的影响规律。搭建了分别含单块LiNbO3晶体、LiNbO3晶体和薄片、两块串联LiNbO3晶体的Ho,Tm,Cr:YAG激光电光调Q实验装置,并测得了输出激光的偏振态、输出能量等随晶压的变化关系曲线。     

Quark Gluon Condensate, Virtuality and Susceptibility of QCD Vacuum

We study vacuum of QCD in this work. The structure of non-local quark vacuum condensate, values of various local quark and gluon vacuum condensates, quark-gluon mixed vacuum condensate, quark and gluon virtuality in QCD vacuum state, quark dynamical mass and susceptibility of QCD vacuum state to external field are predicted by use of the solutions of Dyson-Schwinger equations in ＂rainbow＂ approximation with a modeling gluon propagator and three different sets of quark-quark interaction parameters. Our theoretical predictions are in good agreement with the correspondent empirical values used widely in literature, and many other theoretical calculations. The quark propagator and self-energy functions are also obtained from the numerical solutions of Dyson Schwinger equations. This work is centrally important for studying non-perturbative QCD, and has many important applications both in particle and nuclear physics.     

不同波长的散射介质后向散射光偏振度特性

基于Stockes矢量,通过测量以线偏振光和圆偏振光入射时脂肪乳剂后向散射光的偏振度,研究了532nm、650nm和780nm三个波长的光与散射粒子粒径为325nm的脂肪乳剂溶液作用后,其后向散射光的偏振度特性.研究结果表明,对于入射线偏振光,780nm波长后向散射光中的线偏振光成分多于圆偏振光成分,而532nm波长则相反;对于入射圆偏振光,三个波长后向散射光中的圆偏振光成分均多于线偏振光成分;532nm波长的总偏振度高于650nm和780nm两个波长各自的总偏振度;线偏振光的保偏性优于圆偏振光的保偏性,但偏振光在散射介质中的穿透深度较小.因此,后向散射成像技术适用于物体表层成像,而且选择波长略大于粒径的线偏振光可以提高成像质量.     

不同波长的散射介质后向散射光偏振度特性

基于Stockes矢量,通过测量以线偏振光和圆偏振光入射时脂肪乳剂后向散射光的偏振度,研究了532 nm、650 nm和780 nm三个波长的光与散射粒子粒径为325 nm的脂肪乳剂溶液作用后,其后向散射光的偏振度特性.研究结果表明,对于入射线偏振光,780 nm波长后向散射光中的线偏振光成分多于圆偏振光成分,而532 nm波长则相反;对于入射圆偏振光,三个波长后向散射光中的圆偏振光成分均多于线偏振光成分;532 nm波长的总偏振度高于650 nm和780 nm两个波长各自的总偏振度;线偏振光的保偏性优于圆偏振光的保偏性,但偏振光在散射介质中的穿透深度较小.因此,后向散射成像技术适用于物体表层成像,而且选择波长略大于粒径的线偏振光可以提高成像质量.     

基于洛匈棱镜的偏振度测量与空间退偏度分析方法研究

空间平均型退偏要求退偏后的光束不仅具有低偏振度,还要求避免偏振态的空间带状连续分布.为了实现光束偏振度的测量和空间退偏度的观察,提出基于洛匈棱镜的偏振度测量方法,理论推导了偏振度和各个光功率测量值之间的关系,设计了实验装置,并与全偏振度测量方法进行对比.结果显示:两种测量方法得到的偏振度相对偏差为0.192%,但洛匈棱镜能将o光和e光在空间分离,能对光束偏振态的空间分布进行观测.基于洛匈棱镜的偏振度观测方法结构简单,操作方便,在偏振度和偏振态的空间分布的同时观测中有重要应用.     

被驱动的V型三能级原子在压缩真空中的稳态行为

研究了相干驱动的Ｖ型三能级在原子在压缩真空入射的劣质腔中的稳态行为,分析了原子的稳态粒子布居数与库场平均光予数、压缩关联强度和相位及相干激光场的强度的关系。对相干捕获现象的发生作了讨论。     

沙尘气溶胶粒子群的散射和偏振特性

根据Mie散射理论,以对数正态分布函数描述沙尘气溶胶粒子群的粒径尺度分布,计算了沙尘气溶胶粒子群在0.2～40μm波段间对太阳短波辐射和地球大气长波辐射的单次散射反照率、散射相矩阵函数,揭示了不同相对湿度时,沙尘粒子群对入射辐射的散射和偏振的特征。结果表明,沙尘粒子群的单次散射反照率随着入射波长的增加有较大起伏,不同相对湿度条件下,变化趋势基本一致;在可见光、近红外波段单次散射反照率随湿度增加而变大,湿度95%时非常接近于1;大于10μm的热红外波段单次散射反照率随相对湿度增加而减小,具有较强的吸收辐射能力。散射辐射强度受湿度影响较小,随散射角的增加呈现先减小后增大的趋势,且增大的趋势随着波长的增加而减弱;不同波段上,线偏振和圆偏振随散射角和相对湿度变化存在差异;在前向和后向仅对入射辐射为圆偏振辐射产生圆偏振散射;散射光的偏振特性及其湿度差异主要表现在后向散射区,多以拱形形式体现。拱顶峰值散射角位置存在差异,且峰值散射角随相对湿度的降低向后向漂移。     

Calculation of Curvature Vacuum Correlations in R-Gravity

Under the flat Minkowski space-time background, using the perturbative expansion of the metric density, we calculate the expressions of the leading terms of several two-point curvature vacuum correlation functions in N-dimensional R-gravity, resulting in that the contributions of the leading terms of the curvature vacuum correlation functions are all vanishing.     

基于偏振度的偏振模色散补偿中检测信号对不同归零码型的响应研究

从理论上数值分析和比较了一阶和二阶偏振模色散对各种光调制码型（RZ、CSRZ、RZ-DPSK、CSRZ-DPSK）的偏振模色散的影响,结果表明:不同码型的偏振度大不相同,RZ码受偏振度影响最大,CSRZ-DPSK码受二阶偏振模色散的影响最小,在补偿系统中更适合缓解偏振模色散.