Table of contents

20 June 1998, Volume 7 Issue 6 Previous issue    Next issue

GENERAL

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EFFECTIVE POTENTIAL OF $\lambda$$\phi$41+3 AT ZERO AND FINITE TEMPERATURES NI GUANG-JIONG (倪光炯), CHEN SU-QING (陈苏卿) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  401-413.  DOI: 10.1088/1004-423X/7/6/001 Abstract ( 970 )   PDF (333KB) ( 381 )   The effective potential of $\lambda$$\phi$41+3 model with both signs of parameter m2 is evaluated at T=0 by means of a simple but effective method for regularization and renormalization. Then at T≠0, the effective potential is evaluated in imaginary time Green function approach, using the Plana formula. A critical temperature for restoration of symmetry breaking in the standard model of particle physics is estimated to be Tc ≌ 510 GeV.

ATOMIC AND MOLECULAR PHYSICS

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LASER COOLING IN PHASE FLUCTUATING LASER FIELD LI YI-MIN (李义民), YANG DONG-HAI (杨东海), WANG YI-QIU (王义遒) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  414-421.  DOI: 10.1088/1004-423X/7/6/002 Abstract ( 1091 )   PDF (231KB) ( 343 )   The influence of laser linewidth $\varGamma$1 on laser cooling of atoms was investigated theoretically by using a diffusing phase model. The final tempe rature which can be achieved by Doppler cooling or sub Doppler cooling in phase fluctuating laser field is presented. It was found that the natural linewidth $\varGamma$n of the transition used for cooling the atoms is an important quan tity in evaluating the influence of $\varGamma$1 under Doppler cooling mechanism, and the laser linewidth has little effect on the final temperature under sub-Doppler cooling mechanism because the laser detuning is very large in this case.

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COHERENT POPULATION TRAPPING IN MULTILEVEL LASER-INDUCED CONTINUUM STRUCTURE SYSTEM INCLUDING CASCADE TWO-PHOTON PROCESSES LI GAO-XIANG (李高翔), HUANG GUANG-MING (黄光明), PENG JIN-SHENG (彭金生) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  422-431.  DOI: 10.1088/1004-423X/7/6/003 Abstract ( 1150 )   PDF (308KB) ( 328 )   We have investigated the atomic coherent population trapping in a multilevel laser-induced continuum structure system including cascade two-photon processes, in which two sets of quasicontinua of excited levels to be modeled as the Bixon-Jortner quasicontinuum are laser-embedded into a previously structureless atomic continuum.The condition leading to the atomic coherent population trapping and the coherent population trapping state are given explicitly. And the effects of the Fano factors, the laser intensities and the detunings on the amount of population trapped in the atomic bound states and the populations distributed in the two sets of quasicontinua are also examined.

CLASSICAL AREAS OF PHENOMENOLOGY

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TOTAL REFLECTION CHARACTERISTICS OF PLANE WAVES AT THE INTERFACE INCLUDING A CHIRAL MEDIUM LI ZHAN-JIE (李占杰), XIONG YUAN-SHENG (熊元生), LIU ZU-LI (刘祖黎), YAO KAI-LUN (姚凯伦) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  432-436.  DOI: 10.1088/1004-423X/7/6/004 Abstract ( 1053 )   PDF (135KB) ( 379 )   The total reflection characteristics of plane waves from the interfac e including a chiral medium have been studied with complex chiral material param eters. The possible values of chirality admittance $\zeta$c are determined for left-circularly polarized (LCP) and right-circularly polarized (RCP) total reflections at fixed incident angles from an interface between free space and a chiral medium. It is found that there exists a region of parameter $\zeta$c , in which neither LCP nor RCP modes can be totally reflected for any incident angle $\theta$. It is demonstrated that for $\zeta$1 = Re ($\zeta$c)＞0, total reflection is preferred for LCP mode whereas RCP total reflection is favored for $\zeta$1＜0.

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QUANTUM CONNECTION BETWEEN THE IONS IN DIFFERENT TRAPS JIN ZHEN (金振), GUO GUANG-CAN (郭光灿) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  437-442.  DOI: 10.1088/1004-423X/7/6/005 Abstract ( 1069 )   PDF (206KB) ( 381 )   In this paper, we suggest a way to perform coherent quantum arithmetic operation on the ions in different traps by interaction-free measurement. The physical processes and implementation steps of the controlled-NOT operation are carefully investigated. This method is, in effect, to connect different ion tr a ps into one larger integral quantum register. Thus the more complex logic operat ions, as well as the quantum algorithm such as the Shor algorithm whose realizat ion needs thousands of pubits, perhaps will be implemented through this way. It is also pointed out that this method is potentially useful in quantum cryptograp hy and quantum communication.

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TEMPORAL BEHAVIOR OF PHASE-CONJUGATE OUTPUTS IN A COHERENTLY INDUCED PHASE CONJUGATOR SUN XIU-DONG (孙秀冬), FENG YU-WEN (冯玉文), JIANG YONG-YUAN (姜永远), LI YAN (李焱), ZHOU ZHONG-XIANG (周忠祥) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  443-450.  DOI: 10.1088/1004-423X/7/6/006 Abstract ( 937 )   PDF (255KB) ( 296 )   The temporal behavior of the bidirectional phase-conjugate outputs from a coherently induced phase conjugator has been observed on a Cu-doped barium strontium potassium sodium niobate crystal. In our experiment, the phase-conjugate outputs of two incident beams vary smoothly with time if the beam ratio is large. When the beam ratio is reduced, however, each phase conjugate output will experience a temporal fluctuation. The phase-conjugate output characteristic is found to be dependent on the beam ratio of the two input beams, their positions, their beam-path-length difference and sometimes the input order of the two beams. We present a model of multi-region-interaction to explain the operation of the device and the experimental results in this paper.

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THE THERMAL DIFFUSIVITIES OF NANOSTRUCTURED NiAl ALLOYS MEASURED BY USING PHOTOACOUSTIC TECHNIQUE DU YING-LEI (杜英磊), WU BAI-MEI (吴柏枚), QIN XIAO-YING (秦晓英), ZHANG LI-DE (张立德) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  451-457.  DOI: 10.1088/1004-423X/7/6/007 Abstract ( 1137 )   PDF (250KB) ( 402 )   The thermal diffusivities of nanostructured NiAl (n-NiAl) alloys wit h different relative densities and the polycrystalline NiAl alloy are measured by using photoacoustic technique in which the signal is detected at the front surface while the rear-surface is excited. It is shown that the values of thermal diffusivity of the nanostructured NiAl alloy are lower than that of the polycry stalline NiAl alloy. The thermal diffusivities of n-NiAl alloys decrease with t he decrease of their relative densities when they are over 70%. When the relativ e density of n-NiAl alloys is lower than 70%, an anomalous increase of thermal diffusivity is observed, which indicates there exists a critical excess volume ΔVc (or critical relative density) in n-NiAl alloys near 70%. Th e results are discussed.

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

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MAGNETIC AND ELECTRICAL PROPERTIES OF TWO POLYANILINE FAMILIES:PANI-H3PO4 and PANI-C4H6O6 ABDULKADER M.ELAMIN, LIU ZU-LI (刘祖黎), YAO KAI-LUN (姚凯伦) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  458-463.  DOI: 10.1088/1004-423X/7/6/008 Abstract ( 1301 )   PDF (152KB) ( 355 )   We report a comparative study between two kinds of polyaniline, PANI-H3PO4 and PANI-C4H6O6. We have measured the temperature dependence of the dc-conductivity $\sigma$dc(T) and magnetic susceptibility $\chi$T(T). The structure of polyaniline was characterized by F ourier transform infrared technique, electron-spin-resonance and X-ray diffraction. Polyanil ine synthesized with phosphoric and tartaric acids leads to high magnetic suscep tibility $\chi$T (at T=295 K)≈10-4 emu/mol.2rings. The dc-conductivity of both kinds of PANI shows a semiconductor behavior and follows the quasi one-dimensional variable-range-hopping model. A compa rison of the magnetic susceptibility shows greater electron localization in PANI-C4H6O6, which is in agreement with the lower conductivity at room temper ature for PANI-C4H6O6.

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THREE-ELECTRON SYSTEMS IN SPHERICAL PARABOLIC GaAs QUANTUM DOTS XIE WEN-FANG (解文方), CHEN CHUAN-YU (陈传誉) Acta Physica Sinica (Overseas Edition), 1998, 7 (6):  464-468.  DOI: 10.1088/1004-423X/7/6/009 Abstract ( 1040 )   PDF (144KB) ( 344 )   By making use of the method of few-body physics,the energy spectra of low-lying states of a three-electron spherical dot have been calculated. The quantum-size effects on the energy spectra of three electrons are shown.The res ults show that the orders of energy levels do not change when quantum dot diamet ers change. As a result, the energies of the states of L=3k (k=1,2,…) fulfilling $\pi$ (-1)L=1 are lower than those of their adjacent states.