Table of contents

15 June 1999, Volume 8 Issue 6 Previous issue    Next issue

GENERAL

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ENTANGLED STATES OF CAVITY FIELDS VIA THE RAMAN INTERACTION Fang Mao-fa (方卯发), Zhou Qing-ping (周清平), Zhou Peng (周鹏) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  401-408.  DOI: 10.1088/1004-423X/8/6/001 Abstract ( 1358 )   PDF (248KB) ( 431 )   A scheme to generate the two-mode field entangled states is proposed, based on the Raman interaction of an effective two-level atom with the pump and Stokes fields. The degree of the entanglement between the two field modes in the entangled states is also studied.

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LARMOR PRECESSION AND THE BARRIER INTERACTION TIME Liang Jiu-qing(梁九卿), Ding Xiu-xiang (丁秀香) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  409-415.  DOI: 10.1088/1004-423X/8/6/002 Abstract ( 1119 )   PDF (199KB) ( 549 )   The Larmor precession of a spinning particle in a magnetic field confined in the region of one dimensional-rectangular barrier is investigated with the spin coherent state of incoming particle, which has advantage to recognize the equation of the spin precession. Our new observation is that the precession time of spin is uniquely determined and is seen to be equal to the dwell time.

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CONTROLLING HOPF BIFURCATIONS: CONTINUOUS-TIME SYSTEMS Chen Guan-rong (陈关荣), Fang Jin-qing (方锦清), Hong Yi-guang (洪奕光), Qin Hua-shu (秦化淑) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  416-422.  DOI: 10.1088/1004-423X/8/6/003 Abstract ( 1206 )   PDF (230KB) ( 496 )   Bifurcation control has attracted increasing attention in recent years. A simple and unified state-feedback method is developed in this paper for Hopf bifurcation control for continuous-time systems. The control task can be eit her shifting an existing Hopf bifurcation or creating a new Hopf bifurcation. Some computer simulations are included to illustrate the method and verify the theoretical results.

ATOMIC AND MOLECULAR PHYSICS

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EXCITATION ENERGIES OF 1s2nd AND 1s2nf STATES FOR THE LITHIUM ISOELECTRONIC SEQUENCE Qu Lian-hua (屈连华), Wang Zhi-wen (王治文), Li Bai-wen (李白文) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  423-429.  DOI: 10.1088/1004-423X/8/6/004 Abstract ( 1325 )   PDF (195KB) ( 439 )   The nonrelativistic energies of the 1s2nd and 1s2nf(n=6, 7, 8 and 9) states for the lithium isoelectronic sequence from Li I to Ne VⅢ are calculated by using a full core plus correlation method with multiconfiguration interaction wave function. Relativistic and mass-polarization effects on the energy are evaluated as the first-order pertur bation theory. In most cases with nuclear charge, Z≤7, the agreement between our predicted excitation energies and the experimental data is less than 1cm-1.

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CALCULATION OF HIGHLY EXCITED VIBRATIONAL ENERGY LEVELS OF CH3CN MOLECULE BY NON-LINEAR QUANTUM THEORY Zhu Jun (朱俊), Gou Qing-quan (芶清泉) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  430-433.  DOI: 10.1088/1004-423X/8/6/005 Abstract ( 1351 )   PDF (166KB) ( 410 )   A three-parameter nonlinear dynamical model, i.e., the quantized discrete self-trapping equation, was used to calculate the highly excited CH stretching vibrational energy levels of liquid phase CH3CN molecule in the electronic ground state up to n=7. The calculated results show that the experimental energy levels can be well described by the model.

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ACCURATE QUANTUM CHEMICAL CALCULATION OF CROSS SECTIONS FOR THE SYSTEM D+H2→DH+H Ren Ting-qi (任廷琦) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  434-436.  DOI: 10.1088/1004-423X/8/6/006 Abstract ( 1433 )   PDF (159KB) ( 376 )   Accurate reactive scattering calculations of reactive probabilities and integral cross sections for the system D+H2→DH+H were carried out by using the quantum mechanical time-dependent wave packet methods. In order to simplify the calculation, we introduced the centrifugal sudden approximation to reduce the effective degrees of freedom, and show results of new calcul ations. In particular, the present calculations were extended to all angular momentum and obtained reaction cross sections for a range of energies. The results were also compared with those of other theoretical calculations and the differences were discussed.

CLASSICAL AREAS OF PHENOMENOLOGY

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INTERFEROMETRIC DETECTION OF OPTICAL PHASE SHIFT USING TWIN BEAMS Zhang Jun-xiang (张俊香), Zhang Tian-cai (张天才), Xie Chang-de (谢常德), Peng Kun-chi (彭堃墀) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  437-442.  DOI: 10.1088/1004-423X/8/6/007 Abstract ( 1223 )   PDF (195KB) ( 352 )   An interferometric detection scheme to measure optical phase shift with sensi tivity beyond the shot noise limit is proposed. The theoretical calculation shows that using the quantum correlated twin beams produced from an optical parametric amplifier as the input fields of a Mach-Zehnder interferometer, the minimum detectable phase shift will exceed the shot noise limit N-1/2 and approach the Heisenberg limit N-1. The parametric dependences of the minimum detectable phase shift on the nonlinear interaction, input photon number, and detection efficiency are shown.

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ELECTROMAGNETICALLY INDUCED TWO-PHOTON TRANSPARENCY IN V MODEL Yang Su-hui (杨苏辉), Wang Dong (王冬), Gao Jin-yue (高锦岳) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  443-448.  DOI: 10.1088/1004-423X/8/6/008 Abstract ( 1174 )   PDF (186KB) ( 488 )   A new scheme of electromagnetically induced two-photon transparency in a four-level V-type Doppler-broadened medium is presented in this paper. Under a proper condition, the two-photon absorption can be greatly reduced by applying a control laser field with relatively lower intensity compared with that needed in other field-induced multi-photon absorption reduction.

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ANALYSES OF OUTPUT CHARACTERISTICS FOR FOUR-LEVEL SYSTEM LASER Huang Li-lei (黄莉蕾), Fang Da-wei (方达伟), Hong Zhi (洪治) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  449-454.  DOI: 10.1088/1004-423X/8/6/009 Abstract ( 1172 )   PDF (210KB) ( 501 )   From transition-rate-equations and transmission-equations the formulas of threshold power and slope efficiency of an end-pumped laser for a four-level system are deduced. Citing the laser of Er:YAG as an example, we have discussed the differences of laser output characteristics between the three-and four-level systems.

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

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STUDIES OF NANOCRYSTALLINE PHASE AND RESIDUAL AMORPHOUS PHASE OF FeCuNbSiB ALLOY Lin De-ming (林德明), Wang Hua-sheng (王华生), Wu Yi-chu (吴奕初), Lin Mu-liang (林木良) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  455-462.  DOI: 10.1088/1004-423X/8/6/010 Abstract ( 1053 )   PDF (235KB) ( 451 )   The $\sigma$-T and d$\sigma$/dT-T curves of the FeCuNbSiB amorphous alloy, which are the relationship between "apparent weight loss" and tempera ture, are investigated by magnetic thermogravimetry analysis (MTGA) technique. It is found that the crystallization process of the samples can be divided into five stages. The studies of samples annealed in the temperature range of 480-610℃ for 1 h show that when the annealing temperature (Ta) is lower than 540℃, the quantity of nanocrystalline $\alpha$-Fe(Si) phase increases evidently with Ta, and the Curie temperature (Tc) of residual amorphous phase also increases linearly with Ta, i.e., Tc=0.52Ta+91.7℃, with correlation coefficient $\gamma$=0.98. The variation of volume fraction of $\alpha$-Fe(Si) nanocrystalline phase or residual amorphous phase with Ta is measured.

RAPID COMMUNICATION

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PERFORMANCE COMPARISON OF THE NEON-LIKE CHROMIUM SOFT X-RAY LASING DRIVEN BY A DOUBLE LASER PULSE WITH DIFFERENT DURATION Li Yu-tong (李玉同), Gu Yu-qiu (谷渝秋), Li Ying-jun (李英骏), Zhang Jie (张杰), Chun-yu Shu-tai (淳于书泰), You Yong-lu (尤永禄), He Shao-tang (何绍堂), Huang Wen-zhong (黄文忠), He Ying-ling (何颍玲), Lu Li-zhu (陆丽珠), Yuan Xiao-dong (袁晓东), Wei Xiao-feng (魏晓峰), Zhang Chuan-fei (张传飞) Acta Physica Sinica (Overseas Edition), 1999, 8 (6):  463-468.  DOI: 10.1088/1004-423X/8/6/011 Abstract ( 1186 )   PDF (215KB) ( 581 )   A comparison has been made of performance of the neon-like chromium soft X-ray lasing at 28.5 nm driven by a double 900 ps pulse at 6 TW/cm2, with that driven by a double 200 ps pulse at similar irradiance. The double 200 ps pulse has been found to be much more efficient to drive X-ray lasing with higher intensity.