Vol. 40, No. 3 (1991)
1991, 40 (3): 329-336. doi: 10.7498/aps.40.329
The q-oscillator is studied in the case of q being roots of unity, and SUq(2) and SUq(1, 1), the algebras realized through the oscillators are indicated. The excitations are found to be non-bosonic and the classical mechanical counterparts are given. Especially when rank k is 4 and 6, the excitations are shown to be fermi and parafermi like respectively. Short comment upon  is given to show that parts of the results therein are trivial.
1991, 40 (3): 337-344. doi: 10.7498/aps.40.337
We point out that the usual quantum enveloping algebra can be realized at classical level in the sense of Poisson bracket. As an example, we give the classical realization of Uq(SU(2)) by a system of classical harmonic oscillators. We show that the q-deformation corresponds to Beltrami deformation of the complex coordinate of phase space, ? quantization of the system of the classical deformed oscillators is also discussed, Uq(SU(2)) algebra in Lie bracket obtained.
The concept of Berry's phase factor in adiabatic process is generalized to degenerate systems, the relation between the quantum Hall effect and Berry's phase factor is studied. It is shown that the quantum Hall conductance σH is really a special Berry's phase factor, and thus has the same geometrical properties.
1991, 40 (3): 353-358. doi: 10.7498/aps.40.353
A global monopole produces a repulsive gravitational field outside the core in addition to a solid angular deficit, rather than an attractive gravitational field suggested in previous literatures. The global monopole-antimonopole annihilation mechanism and the geodesies are also studied.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
This work presents a simple and effective inethod for obtaining the exact soliton solutions of the coupled relativistic scalar field theory. The exact solutions obtained are new and important. The method suggested here can be applied to other coupled nonlinear systems as well.
CLASSICAL AREA OF PHENOMENOLOGY
INFLUENCE OF FEEDBACK STRENGTH ON THE OSCILLA-TION PATTERN IN OPTICAL SYSTEM WITH COMPETING INTERACTIONS
1991, 40 (3): 365-374. doi: 10.7498/aps.40.365
In this paper, we report the influence of feedback strength on the oscillation pattern in optical system with competing interactions. The frequency locking, frequency jump between neighboring modes and the hysteresis phenomenon are observed. Our computation and experimental results verify that the feedback strength is the competing interaction source.
MULTI-PHOTON SPECTRUM OF TRANSMITTED LIGHT FOR THE MIXED ABSORPTIVE-DISPERSIVE DRIVEN OPTICAL SYSTEM IN GOOD CAVITY CASE
1991, 40 (3): 375-385. doi: 10.7498/aps.40.375
In this paper, the multi-photon spectrum of transmitted light for the mixed absorptive-dispersive optical system in good cavity case is discussed. Owing to the influence of detuning θ and △, not all the various peak values of the spectrum appear at the point of ω = ω0, and the coefficient of different peak value is not the same. Therefore, the spectrum of transmitted light will show various characters, such as single peak, multi-peaks or asymmetric ones.
1991, 40 (3): 386-392. doi: 10.7498/aps.40.386
The higher-order squeezing and quasiprobability distribution function of even and odd coherent states are studied in this paper. The results show that the properties of higher-order squeezing of the two states exclude each other, and characteristic functions and Wigner functions are all not gaussian. Particularly, Wigner functions can not be perseved positive define. Quasiprobability density (QPD) of the two states are neither "elliptic" nor "crescent", but are two-petal-like shape, which shows that squeezing type can not be represented by the QPD figure of a state.
1991, 40 (3): 393-398. doi: 10.7498/aps.40.393
The general expression of the statistical distribution function of photons in two-photon Jaynes-Cummings model (JCM) is derived. The expression can be applied to the cases of any initial light field and any initial atomic state. Under exact two-photon resonance, the features of evolution for the statistical distribution of photons in JCM with the initial coherent state field and the initial squeeze state field are studied in detail. These two cases show striking difference.
The thermal conduction theory based on uniform heating in the slab laser has presented before, but the results obtained from this theory disagree considerably from the results of experiment. In this paper, a non-uniform heating model based on the absorption law of medium is proposed. According to this model, the temperature distribution in the slab laser under CW and pulse pumping is solved. Thermal stress and fracture limitation of the slab are given. The new model is in accordance with the experimental results.
1991, 40 (3): 407-413. doi: 10.7498/aps.40.407
In this paper the transformation-circle diagrammatic approach is developed. Using this method, the general solution of the thermal-insensitive resonator is derived, that is, the σ1 circle is tangential to the πf circle. Its main characters arc elucidated clearly. Some inaccurate current points of view on its characters are made clear. Furthermore, the special solution of the optimal thermal-insensitive resonator is obtained, that is, g1*g2*=1/2; L2= 0 or L2=R2.
MULTILEVEL THEORY OF TIME-DELAY FOUR-WAVE MIXING WITH INCOHERENT LIGHT——INHOMO-GENEOUS BROADENING CASE
1991, 40 (3): 414-423. doi: 10.7498/aps.40.414
In this paper, our multi-level theory of time-delay four wave mixing with incoherent light (TDFWM-IL) developed previously for the case of homogeneous broadening system has been extended to a generally inhomogeneous broadening case. From the present theory, a general expression of signal intensity for absorption band with both homogeneous and inhomogeneous broadening is given as a function of mutual time delay τ between two pump beams. Photon echo with incoherent light under the condition of extremely inhomogeneous broadening is discussed, and the difference of results obtained scperately from multi-level and two-level theory is pointed out. It has been demonstrated that the experiment of TDFWM-IL can also be analysed approximately by using an effective two-level model when a weak effect of inhomogeneous broadening of absorption band exists. Finally, our experimental results of TDFWM-IL obtained at zero-phonon line of ruby and absorption edge of cresyl violet film in PMMA are also presented and compared with the theory mentioned above.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1991, 40 (3): 424-432. doi: 10.7498/aps.40.424
In this paper, the scaling laws between the X-ray temperature and the X-ray energy converted by laser have been studied analytically for the laser cylindrical cavity targets according to the information of the experiments and the numerical simulations. For a series of experiments made on the Shenguang facility in 1989, we predict that, as the laser energy of each beam is 300-500J, the pulse width is 0.7-1.0ns, and the wavelength is 1.06 μm, the X-ray conversion efficiency is about 50-55% for the two beam targets, and the corresponding X-ray temperature is about 1.5×106-1.7×106K.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
INVESTIGATION OF THE SEMICONDUCTOR STRAINED SUPERLATTICE STRUCTURE AND INTERFACE BY X-RAY ROCKING-CURVE ANALYSIS
1991, 40 (3): 433-440. doi: 10.7498/aps.40.433
The dynamical theory as developed by Takagi and Taupin for imperfect crystals has been applied to analyse the intensity distribution of the superlattice diffraction peaks, and to compute the rocking curves when the interface grading and the period thickness fluctuation are present. The reason why the interference fringes between the superlattice diffraction peaks disappear and the superlattice diffraction peaks broaden are discussed. It is clear that the intensity distribution of the superlattice diffraction peaks depends on the superlattice period thickness, the composition and strain in it. The interface gradient and the period thickness fluctuation may affect the double-crystal rocking curves. The main reason of the superlattice diffraction peak broadening is the bending of lattice plane.
1991, 40 (3): 441-448. doi: 10.7498/aps.40.441
In this paper, the analysis of GexSi1-x/Si strained layer superlattice grown by MBE is made by means of X-ray double crystal diffraction. The structure parameters of GexSi1-x/Sisuperlattice is obtained from the simulation of rocking curve based on X-ray kinematical and dynamical diffraction theory respectively. The results calculated with these two theories is almost the same, there is a little difference only in the fine structure of rocking curve. For the high quality GexSi1-x/Si superlattice, the rocking cu rve calculated with X-ray dynamical theory is more close to the experimental curve than that with X-ray kinematical theory.
There is a special area in KTP crystal, in which the SHG efficiency is obviously increased. In this paper, the KTP crystal is studied by means of Synchrotron Radiation (SR) White Beam Topography, and a planar defect is found in such an area. The lattice is deformed because of the accumulation of impurity in this area, which results in the increase of SHG efficiency. The maximum strain direction is determined to be R=〈010〉 according to the extinction condition of planar defect.
1991, 40 (3): 454-458. doi: 10.7498/aps.40.454
The band of charge transfer transition was detected in optical absorbtion spectra when molecule adsorbed on the silver surface in silver sol. The process of charge transfer between molecule and surface was mainly studied and some explanations were given.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
EFFECT OF STRAIN ON THE BULK AND THE SURFACE ELECTRONIC STRUCTURES OF (GaP)1/(InP)1(111) SUPERLATTICE
1991, 40 (3): 459-468. doi: 10.7498/aps.40.459
Under the tight-binding formalism, this paper suggests that effect of strain can be considered in terms of Harrison's interatomic matrix elements, taking acount of the homogeneous bond stretching and bond bending in ultrathin layer (GaP)1/(InP)1(lll) systems. Using recursion method, we have calculated the bulk and the surface electronic structures of the stable (GaP)1/(InP)1(lll) superlattice determined by the Keating model. Our result shows that its band gap is 1.88 eV, which is smaller by 0.31 eV than the average of the calculated gaps of bulk GaP(2.91 eV) and lnP(1.48 eV). As compared with the calculated auxiliary systems, we find that the band gaps of the superlattices become larger and the Fermi levels become lower with the increasing of the strain of the bond length. Furthermore, the obtained number of the occupied electrons on different sites clearly shows that InP is more ionic than GaP. Finally, we show the existence of an approxiamte SPz+Px-Py dehybrid on (111) surface of this strained-layer superlattice and point out that the contribution of S or P partial orbital of a (111) surface atom to this dehybrid is different from the case of a (001) surface atom of GaAs/AlAs (001) superlattice.
1991, 40 (3): 469-475. doi: 10.7498/aps.40.469
Using numerical calculation, it is found that there are extended states, intermadiate states and localized states in the Aubry model of one-dimensional incommensurate systems. The transition from extended states to localized states should pass through a regime in which the intermadiate states exist. The regime is situated at aboubt the potential strength V=2t. The new result is different from that of duality theory which predicts that all states are extended for V2t all states are localized, at V = 2t there exists Anderson transition.
1991, 40 (3): 476-482. doi: 10.7498/aps.40.476
The electrical properties and characteristics of photoluminescence (PL) at 11K for InP implanted with Si+ at 200℃ have been studied. It has been found that the sheet electron concentration in Si+ simply implanted sample tends to a saturation level with increasing the Si+ dose, while that in Si++P+ dually implanted sample increases greatly. The 11K PL spectra reveals that there exists Sip-Vp complex in Si+ implanted InP, which can be inhibited by co-implanting P+. The mechanism of improved electrical properties by Si++P+ dual implants is, also discussed.
1991, 40 (3): 483-489. doi: 10.7498/aps.40.483
Models of trapezoidal barrier in two extreme cases are used in this paper to study barrier parameters of A1-A12O3-M tunnel junctions, the top electrodes of which are Au, Ag and Cu, respectively. From the fitting calculation of V-I characteristics of the above junctions at 77 K, we find that both models can explain the experimental results very well, and the barrier parameters correlate with the atom radius of top electrode metal, the work function of top electrode metal material and the electron affinity to isolarer medium A12O3, respectively.
INFLUENCE OF DOPING BY TRACE Cu OR Mn IN SINTERING PROCESS ON STRUCTURAL TRANSFORMATIONS OF ZnS ELECTROLUMINESCENT PHOSPHOR
1991, 40 (3): 490-497. doi: 10.7498/aps.40.490
The structures of a family of pure ZnS and ZnS eloped by activator Cu and Mn with different concentration ranges under sintering temperature ranging from 600℃ to 1200℃ have been investigated by x-ray powder diffraction method. Using the absolute standard method, the weight ratio of a phase to 3 phase of ZnS microcrystal and the constant Kβα of this method have been determined. The results show that the transition temperature of low temperature βphase to high temperature α phase is 1020℃ for pure ZnS, as generally accepted. When the concentration of doped Cu is in excess of 1×10-3, the phase trasition temperature (PTT) moves obviously to high temperature. As the concentration of Cu reaches 2×10-3, the PTT is higher than 1200℃. The results can be explained by postulating when the concentration of Cu is greater than the solubility of Cu in ZnS, a separate phase of copper sulfide serves as a nucleating phase for the growth of cubic ZnS and thus promotes the hexagonal-to-cubic transition. When the concentration of doped Mn is in excess of 1×10-3, the PTT moves obviously to low temperature. As the concentration of Mn reaches 5×13-3, the PTT is lowered to 730℃. In the range from 700℃ to 950℃, the weights of α phase and βphase are close to each other. The PTT of ZnS: Cu 2×10-3. Mn 5×10-3 are also determined approximately as 1100℃.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1991, 40 (3): 498-504. doi: 10.7498/aps.40.498
In A(BB0.51B0.52)O3 perovskite-like ferroelectrics. besides the stable 1/2〈lll〉-typeordered structure, two new kinds oi ordered structures, 1/2〈110〉 and 1/2〈100〉 superlattices, have been observed at room temperature and -150℃ respectively. In this paper, the longrange interactions are introduced into the eight-point cluster variation method to analyse the stabilities of the three kinds of ordered structures. The results are in good agreement with experimental observations.