当期目录

1998年, 第7卷, 第6期　刊出日期：1998-06-20 上一期    下一期

Select

EFFECTIVE POTENTIAL OF λφ41+3 AT ZERO AND FINITE TEMPERATURES 倪光炯, 陈苏卿 1998 (6):  401-413.  doi: 10.1088/1004-423X/7/6/001 摘要 ( 1064 )   PDF(333KB) ( 397 )   The effective potential of $\lambda$$\varphi$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. 相关文章 | 计量指标

Select

LASER COOLING IN PHASE FLUCTUATING LASER FIELD 李义民, 杨东海, 王义遒 1998 (6):  414-421.  doi: 10.1088/1004-423X/7/6/002 摘要 ( 1197 )   PDF(231KB) ( 367 )   The influence of laser linewidth Γ1 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 Γn of the transition used for cooling the atoms is an important quan tity in evaluating the influence of Γ1 under Doppler cooling mechanis m, 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. 相关文章 | 计量指标

Select

COHERENT POPULATION TRAPPING IN MULTILEVEL LASER-INDUCED CONTINUUM STRUCTURE SYSTEM INCLUDING CASCADE TWO-PHOTON PROCESSES 李高翔, 黄光明, 彭金生 1998 (6):  422-431.  doi: 10.1088/1004-423X/7/6/003 摘要 ( 1249 )   PDF(308KB) ( 345 )   We have investigated the atomic coherent population trapping in a mul tilevel 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 structu reless atomic continuum.The condition leading to the atomic coherent population trapping and the coherent population trapping state are given explicitly. And th e effects of the Fano factors, the laser intensities and the detunings on the am ount of population trapped in the atomic bound states and the populations distri buted in the two sets of quasicontinua are also examined. 相关文章 | 计量指标

Select

TOTAL REFLECTION CHARACTERISTICS OF PLANE WAVES AT THE INTERFACE INCLUDING A CHIRAL MEDIUM 李占杰, 熊元生, 刘祖黎, 姚凯伦 1998 (6):  432-436.  doi: 10.1088/1004-423X/7/6/004 摘要 ( 1192 )   PDF(135KB) ( 414 )   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 ζc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 ζc , in which neither LCP nor RCP modes can be totally reflected for any incident angleθ. It is demonstrated that for ζ1=Re(ζc)＞0,total reflection is preferred for LCP mode whereas RCP total reflection is favored for ζ1＜0. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

Select

QUANTUM CONNECTION BETWEEN THE IONS IN DIFFERENT TRAPS 金振, 郭光灿 1998 (6):  437-442.  doi: 10.1088/1004-423X/7/6/005 摘要 ( 1190 )   PDF(206KB) ( 398 )   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. 相关文章 | 计量指标

Select

TEMPORAL BEHAVIOR OF PHASE-CONJUGATE OUTPUTS IN A COHERENTLY INDUCED PHASE CONJUGATOR 孙秀冬, 冯玉文, 姜永远, 李焱, 周忠祥 1998 (6):  443-450.  doi: 10.1088/1004-423X/7/6/006 摘要 ( 1043 )   PDF(255KB) ( 312 )   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. 相关文章 | 计量指标

Select

THE THERMAL DIFFUSIVITIES OF NANOSTRUCTURED NiAl ALLOYS MEASURED BY USING PHOTOACOUSTIC TECHNIQUE 杜英磊, 吴柏枚, 秦晓英, 张立德 1998 (6):  451-457.  doi: 10.1088/1004-423X/7/6/007 摘要 ( 1275 )   PDF(250KB) ( 433 )   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. 相关文章 | 计量指标

Select

MAGNETIC AND ELECTRICAL PROPERTIES OF TWO POLYANILINE FAMILIES:PANI-H3PO4 and PANI-C4H6O6 ABDULKADER M.ELAMIN, 刘祖黎, 姚凯伦 1998 (6):  458-463.  doi: 10.1088/1004-423X/7/6/008 摘要 ( 1420 )   PDF(152KB) ( 375 )   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 σdc(T) and magnetic susceptibility χT(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 χT(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. 相关文章 | 计量指标

Select

THREE-ELECTRON SYSTEMS IN SPHERICAL PARABOLIC GaAs QUANTUM DOTS 解文方, 陈传誉 1998 (6):  464-468.  doi: 10.1088/1004-423X/7/6/009 摘要 ( 1135 )   PDF(144KB) ( 366 )   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,…)ful filling π (-1)L=1 are lower than those of their adjacent states. 相关文章 | 计量指标