STUDY OF HIGH-LYING EXCITED STATES OF RARE-EARTH ELEMENT Dy BY LASER RESONANCE IONIZATION SPECTROSCOPY

This paper describes the investigation of high-excited states of Dy. which includes the measurement of high Rydberg states and autoionizing states, by means of laser resonance ionization spectroscopy (LRIS). Two high Rydberg series (n>40), 4f¹⁰(⁵I₈) 6sns and 4f¹⁰(⁵I₈) 6snd, have been obtained by exciting the state of 4f¹⁰(⁵I₈) 6s6p (³P⁰₂) ⁵I⁰₈ using two-step laser excitation-electric field ionization method. With the data obtained, we determined the first ionization potential of Dy. It is 47901.7±0.6 cm^-1, that is. about one order more accurate than the results given in the literature. Using the same technique, we found 97 autoionizing states by exciting the state of 4f⁹5d6s(⁷H⁰₇).     

银纳米粒子/碳纳米管阵列SERS基底增强因子分析和实验

为了直观、准确地定量分析表面拉曼增强散射基底结构的拉曼增强,利用磁控溅射和高温退火的方法制备了银纳米粒子修饰垂直排列的碳纳米管阵列三维复合结构样品;实验采用罗丹明6G(R6G)溶剂作为探针分子,结合共聚焦显微拉曼系统,开展了表面增强拉曼增强因子(EF)分析计算的相关实验。SEM结果表明：在有序碳纳米管阵列的表面和外壁均匀地负载了大量银纳米粒子。对退火温度为450 ℃,退火时间为30 min的样品进行了EF计算,得到其增强因子约为2.2×103,并分析了EF值低的原因主要是：在碳纳米管上溅射的银膜膜厚不均匀,导致退火后银颗粒分布不均,使得样品粗糙度值偏大,EF值较低;实验中所用的激励光源并非银纳米颗粒的优化光源。     

Generation of a continuous-wave squeezed vacuum state at 1.3 μm by employing a home-made all-solid-state laser as pump source

We present a continuous-wave squeezed vacuum generation system at a telecommunication wavelength of 1.3 μm. By employing a home-made single-frequency Nd:YVO4 laser with dual wavelength outputs as the pump source, via an optical parameter oscillator based on periodically poled KTP, a squeezed vacuum of 6.1 dB±0.1 dB below the shot noise limit at 1342 nm is experimentally measured. This system could be utilized for demonstrating practical quantum information networks.     

Active Online Learning in the Binary Perceptron Problem

The binary perceptron is the simplest artificial neural network formed by N input units and one output unit, with the neural states and the synaptic weights all restricted to ±1 values. The task in the teacher-student scenario is to infer the hidden weight vector by training on a set of labeled patterns. Previous efforts on the passive learning mode have shown that learning from independent random patterns is quite inefficient. Here we consider the active online learning mode in which the student designs every new Ising training pattern. We demonstrate that it is mathematically possible to achieve perfect(error-free) inference using only N designed training patterns, but this is computationally unfeasible for large systems. We then investigate two Bayesian statistical designing protocols, which require 2.3N and 1.9N training patterns, respectively, to achieve error-free inference. If the training patterns are instead designed through deductive reasoning, perfect inference is achieved using N + log_2N samples. The performance gap between Bayesian and deductive designing strategies may be shortened in future work by taking into account the possibility of ergodicity breaking in the version space of the binary perceptron.     

长程阻错的统计物理理论

一个无序自旋玻璃系统可能有许许多多能量最小态或基态构型．有些格点的自旋可能在所有这些基态中都只取同一个值（这种情况称为自旋凝固）．也有另外一种情况出现，即某些格点在一部分基态中自旋取向上而在其余的基态中自旋向下；这样的格点称为未凝固的格点．本文的工作表明，2个或多个未凝固的格点，虽然每个格点的自旋都随着基态的不同而改变，但是有可能某一些特定的自旋取向组合不会出现于任何一基态构型中．这种现象称为长程阻错．本文提出一个新的长程阻错序参量R来定量刻划这种现象，并将这一统计物理理论用于图的最小覆盖和K—SAT等组合优化问题．     

Solution Space Coupling in the Random K-Satisfiability Problem

The random K-satisfiability(K-SAT)problem is very difcult when the clause density is close to the satisfiability threshold.In this paper we study this problem from the perspective of solution space coupling.We divide a given difcult random K-SAT formula into two easy sub-formulas and let the two corresponding solution spaces to interact with each other through a coupling field x.We investigate the statistical mechanical property of this coupled system by mean field theory and computer simulations.The coupled system has an ergodicity-breaking(clustering)transition at certain critical value x d of the coupling field.At this transition point,the mean overlap value between the solutions of the two solution spaces is very close to 1.The mean energy density of the coupled system at its clustering transition point is less than the mean energy density of the original K-SAT problem at the temperature-induced clustering transition point.The implications of this work for designing new heuristic K-SAT solvers are discussed.     

第24届国际统计物理大会记事

1 Cairns印象 2010年7月17日搭乘香港往Cairns的国泰午夜航班,安顿下来后,眯上眼睛刚进入梦乡,飞机已开始降落.第一次踏上南半球的土地,学生时代的好奇和兴奋未减,跟前的景色却又一次无情地证明了地球村的有限.Cairns是澳大利亚东北部的一座海滨小镇,清新、安逸、平和、山水相依,天空优雅飞翔的海鸟和海滩上健身慢跑的人影,让人想起加州、地中海或我们山东半岛的一座座海滨城镇.如果不是太阳从东往北逆时针移动,还真不觉得已来到了袋鼠的故乡.     

彭桓武先生与青年研究生

在考入中国科学院理论物理研究所做研究生之前,我们就从各种渠道得知,彭桓武先生早年是清华大学物理系的“四杰”之一,研究生毕业不久,即远涉重洋赴英国爱丁堡拜师马克斯·玻恩从事固体物理研究,之后受薛定谔之聘两次前往都柏林高等研究院,与海特勒合作从事介子物理研究,还与玻恩合作研究量子场论,取得当时国际知名的研究成果.1947年回国后,转向核物理和核工程,带出一批又红又专的研究生,并带领他们开展我国反应堆和核武器理论设计工作,为我国“两弹一星”研制做出巨大的历史性贡献,是我们心目中功劳大、学问大的大师.彭先生为了祖国的核事…     

锰(Ⅱ)-胡椒碱-溴化十六烷基三甲基胺三元体系的荧光特性及应用

The fluorescence characteristics of the complex of piperine with cation in micellar system were studied. At the same time, the influence of experimental condition on the fluorescence intensity was also studied. The experiments indicated that piperine had very low fluorescence signal itself. But in pH 8.77 Na₂HPO₄-NaH₂PO₄ buffer solution, both Mn(Ⅱ) and cationic surfactant cetyltrimethylammonium bromide can enhance the fluorescence intensity and stability of piperine. Based on this, a sensitive method has been developed for the quantitative determination of piperine in Mn(Ⅱ)-piperine-cetyltrimethylammonium bromide ternary system. Under the optimum conditions, there is a linear relationship between the enhancement of fluorescence intensity and the concentration of Mn(Ⅱ). The optimal conditions are as follows: the concentration of Mn(Ⅱ) is 2.5×10-4 mol·L-1 and the concentration of cetyltrimethylammonium bromide is 5×10-4 mol·L-1. The fluorescence intensity was determined by a 1 cm quartz cell with the excitation wavelength of 352 nm and the emission wavelength of 452 nm. The linear range of concentration of piperine was 2.02-10.1 μg·mL-1 with the relative coefficient of 0.998 5 and the detection limit of 0.060 2 μg·mL-1. The relative standard deviation (RSD) was 1.10%. The proposed method has been successfully applied to the quantitative determination of piperine in the Mongolian medicine Piper longum L, and the recovery was within the range of 97.6%-102.0%. The results were very satisfactory.     

NEW AUTOIONIZING STATES NEAR THE FIRST IONIZATION LIMIT OF RARE EARTH ELEMENT Dy

This paper describes the investigation of autoionizing states near the first ionization limit of rare-earth element Dy. The 62, 51, 97 and 25 new autoionizing states resulting from the states of 4f¹⁰(⁵I₈)6s6p(³P⁰₂)³I⁰₇, 4f⁹ (⁶H⁰)5d²(³F)(⁸G⁰)6s⁹G⁰₇, 4f⁹(⁶F⁰)5d6s^{2 7}H⁰₇ and 4f⁹5d6s^{2 7}K⁰₇, respectively, were found by using a laser resonance ionization time-of-flight mass spectrometer (LRI-TOFMS), The photoionization efficiencies for different channels were compared with each other. In addition, the Shore-Fano parameters of autoionizing states were determined by a nonlinear fitting program.