Table of contents

15 September 1999, Volume 8 Issue 9 Previous issue    Next issue

GENERAL

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ANALYTIC SOLUTION FOR ONE-DIMENSIONAL QUANTUM OSCILLATOR WITH A VARIABLE FREQUENCY Xu Xiu-wei (徐秀玮), Ren Ting-qi (任廷琦), Liu Sheng-dian (柳盛典) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  641-645.  DOI: 10.1088/1004-423X/8/9/001 Abstract ( 1213 )   PDF (194KB) ( 370 )   According to generalized linear quantum transformation theory, we give the exact expression of the evolution operator, wave function and expectation value of observable quantity for one-dimensional quantum oscillator with a variable frequency: $\omega(t)=\frac{\omega_0}{1+\beta t}(\omega_0, \beta>0)$.

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RELATIVISTIC SPHERES Liu Si-ming (刘四明), Wei Ji-kun (魏霁昆), Hao Li-kun (郝立昆) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  646-650.  DOI: 10.1088/1004-423X/8/9/002 Abstract ( 1012 )   PDF (177KB) ( 316 )   By analyzing the Einstein's equations for the static sphere, we find that there exists a non-singular static configuration whose radius can approach its corresponding horizon size arbitrarily.

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THE CONTROL ACTION OF THE PERIODIC PERTURBATION ON A HYPERCHAOTIC SYSTEM Zhang Xiao-hui (张晓辉), Shen Ke (沈柯) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  651-656.  DOI: 10.1088/1004-423X/8/9/003 Abstract ( 1228 )   PDF (235KB) ( 493 )   This paper presents a four-dimensional nonlinear dynamical system. By the numerical simulation the hyperchaotic attractor, Lyapunov exponents and Lyapunov dimension are obtained, also it is confirmed that hyperchaos can be driven in the system described by the equation. The control action of the periodic perturbation on the autonomous hyperchaotic system is studied, and a control rule is obtained which indicates the relationship of the control action and the frequency characteristics after degeneration of the system. Finaly the circuit implementation of the dynamical system is given.

CLASSICAL AREAS OF PHENOMENOLOGY

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DISTANCE BETWEEN DENSITY OPERATORS IN MULTIPHOTON PROCESSES Zhang Jing-tao (张敬涛), Chen Zhao-yang (陈朝阳), Xu Zhi-zhan (徐至展) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  657-663.  DOI: 10.1088/1004-423X/8/9/004 Abstract ( 1302 )   PDF (223KB) ( 342 )   In this paper we investigate the distance between density operators in multiphoton processes. We study the distances between the time-evolved states of the atom, of the field, and of the total system and their respective reference states, compare them with the atomic inversion as well as the purity of the field, disclose their corresponding relations in various multiphoton processes. The physical interpretations are given by using a fully quantized Bloch equation in the two-photon process.

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THEORETICAL STUDY OF THE INTENSITY DEPENDENCE OF TOTAL EFFECTIVE TRAP DENSITY IN PHOTOREFRACTIVE CRYSTALS Chi Ming-jun (迟明军), Dou Shuo-xing (窦硕星), Ye Pei-xian (叶佩弦) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  664-669.  DOI: 10.1088/1004-423X/8/9/005 Abstract ( 1209 )   PDF (194KB) ( 395 )   Intensity dependence of the total effective trap density Neff is studied theoretically for the two-centre and the three-charge-state photorefractive crystals. The results show that Neff always increases with increasing intensity in three-charge-state crystals, whereas it has more complicated behaviors in two-centre crystals. When SD$\gamma$T/ST$\gamma$D is small, Neff increases and tends to saturate with increasing intensity for both type-A and type-B two-centre crystals. When SD$\gamma$T/ST$\gamma$D is large, Neff increases to a maximum and then decreases a little for type-A crystals and decreases greatly for type-B crystals. The different intensity dependences of Neff in the two types of crystals come from their different level structures.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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PREPARATION OF STRIPE-SHAPED DOMAIN STRUCTURE IN FERROELECTRIC LIQUID CRYSTAL AND THE FABRICATION OF SPATIAL LIGHT MODULATOR Lǜ Rui-bo (吕瑞波), Xu Ke-shu (徐克璹), Zhang Shu-yan (张舒雁), Gu Xiang (顾翔), Xing Zhong-jing (邢中菁), Deng Hui-hua (邓慧华), Gu Jian-hua (顾建华), Xiao Zhong-dang (肖中党), Lu Zu-hong (陆祖宏) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  670-681.  DOI: 10.1088/1004-423X/8/9/006 Abstract ( 1204 )   PDF (324KB) ( 519 )   The stripe-shaped domain (SSD) structure was prepared in the initial ferroelectric liquid crystal (FLC) alignment without the application of an external electric field, which was realized by the aligning layer modification through the doping of tin tetra-2, 4-dimethyl phenoxy phthalocyanine (SnPc) into the rubbed polyimide films. Atomic force microscopy was used to investigate the alignment films and the corresponding aligning ability was evaluated through the pre-tilt angle measurement. The memory capability and the contrast ratio of thus aligned SSFLC cells have been enhanced and improved with the appearance of the SSD structure. The electrically controlled 64×64 FLC spatial light modulator was fabricated using the improved ligning method, which proves valuable for the practical device fabrication.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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TWO-DIMENSIONAL HOT-ELECTRON TRANSPORT IN GaAs-AlGaAs HETEROJUNCTIONS Weng Ming-qi (翁明琪), Wu Hang-sheng (吴杭生) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  682-689.  DOI: 10.1088/1004-423X/8/9/007 Abstract ( 1063 )   PDF (231KB) ( 389 )   The mobility of a two-dimensional electron gas in GaAs-AlGaAs heterojunction is re-computed through solving numerically the balance equation. The peculiarity of the present study lies in that a new expression for the distribution function and the renormalized phonon frequency are used in the computation. Compared with those reported by previous authors, our result shows better agreement with the experimental data.

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A STUDY ON SYNTHESIS OF La1-x SrxCrO3 BY SOL-GEL AND THEIR ELECTRICAL PROPERTIES Liu Xiao-mei (刘晓梅), Yang Min (杨敏), Lǜ Zhe (吕喆), Pei Li (裴力), Liu Jiang (刘江), Su Wen-hui (苏文辉) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  690-693.  DOI: 10.1088/1004-423X/8/9/008 Abstract ( 1266 )   PDF (183KB) ( 441 )   La1-x SrxCrO3 nanoparticles were prepared by the sol-gel method. The sintering temperature of the samples could be decreased to about 400 K. The crystal structures of La1-x SrxCrO3 at room temperature are all of the othorhombic perovskite GdFeO3-type (x≤0.4). And the electrical conductivity increases with x, but when x>0.3 it decreases. The higher the sintering temperature, the better the electrical conductivity, because the grain size of the examples increases with increasing sintering temperature.

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ELECTRONIC STRUCTURE OF THE ZnTe/CdSe(100) INTERFACES WITH ATOM INTERCHANGE Yang Shi-e (杨仕娥), Jia Yu (贾瑜), Ma Bing-xian (马丙现), Shen San-guo (申三国), Fan Xi-qing (范希庆) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  694-701.  DOI: 10.1088/1004-423X/8/9/009 Abstract ( 1287 )   PDF (318KB) ( 465 )   By using the combination of the first-nearest neighbor tight-binding model sp3s* and Green function method in the frame of the scattering theory, we studied the electronic structure of ZnTe/CdSe(100) heterojunction with cation layers interchange across ZnSe-like or CdTe-like interface, and presented the interface band structures and wavevector-resolved interface layer densities of states. By comparing with the electronic states of ideal interfaces, we analyzed the nature and origins of all interface states, and discussed the influence of atom layers interchange on interface electronic structure.

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PHASE SEPARATION AND JOSEPHSON-COUPLING ORIGIN FOR THE ANOMALOUS Hc2 BEHAVIOR IN OVERDOPED Bi2Sr2-xLaxCuO6+$\delta$ CRYSTALS Yang Wan-li (杨万里), Wen Hai-hu (闻海虎), Ni Yong-ming (倪泳明), Zhao Zhong-xian (赵忠贤) Acta Physica Sinica (Overseas Edition), 1999, 8 (9):  702-710.  DOI: 10.1088/1004-423X/8/9/010 Abstract ( 1531 )   PDF (253KB) ( 366 )   Hole-overdoped Bi2Sr2-xLaxCuO6+$\delta$ single crystals with two coexistent superconducting transitions have been intensively studied by measuring the dc magnetic susceptibility. It is found that the coexistence of these two phases cannot be attributed to any chemical or vortex dynamical effect but to some intrinsic driving force, such as the electronic-driven phase separation. Furthermore, the upper critical fields of the two phases behave in a rather different way; that is, one of them shows a "normal Hc2 behavior" which can be described by the critical fluctuation theory, while the other exhibits an "anomalous Hc2 behavior" and can be well explained by a recent theory based on an assumption of a Josephson-coupling origin, indicating a strong evidence of Josephson-coupling origin for the upward curvature of the so-called Hc2 in high Tc superconductors.