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Volume 17 Issue 3
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Original Articles
Perturbative Influence on the Shockwave of Burgers Equation
TANG Yi, YAN Jia-Ren, ZHANG Kai-Wang
Chin. Phys. Lett. 2000, 17 (3): 157-158 .  
Abstract   PDF(pc) (111KB) ( 397 )
From the point of view of evolution equations with soliton solutions, we present a general way for the study of the shockwave of one-dimensional Burgers equation under the action of perturbations. Apart from the damping case which needs a somewhat special treatment, we formulate the effects induced by other general perturbations unifyingly.
On the Spectral Problems for the Discrete Boltzmann Models
Aq Kwang-Hua Chu, J. FANG Jing
Chin. Phys. Lett. 2000, 17 (3): 159-161 .  
Abstract   PDF(pc) (232KB) ( 368 )
The discrete Boltzmann models are used to study the spectral problems related to the one-dimensional plane wave propagation in monatomic gases which are fundamental in the nonequilibrium statistical thermodynamics. The results show that the 8-velocity model can only describe the propagation of the diffusion mode (entropy wave) in the intermediate Knudsen number regime. The 4- and 6-velocity models, instead, can describe the propagation of sound modes quite well, after comparison with the continuum-mechanical results.

Multiparticle Generalization of Teleportation
YANG Chui-Ping, GUO Guang-Can
Chin. Phys. Lett. 2000, 17 (3): 162-164 .  
Abstract   PDF(pc) (276KB) ( 531 )
A scheme for teleporting an unknown quantum state of many particles is proposed. The scheme operates essentially by prearranging the sharing of an Einstein-Podolsky-Rosen-correlated pair of particles every time. We show that after performing a series of Bell-state measurements and single-particle unitary transformations, the unknown state of many particles, which was destroyed at one place, can be reconstructed at another place. Our scheme is actually obtained by generalizing an earlier scheme of Bennett et al. [Phys. Rev. Lett. 70 (1993) 1895;76 (1996) 722] known as quantum teleportation to the multiparticle case.

A Scheme of Interferometric Measurement of an Atomic Wave Function
LIU Zheng-Dong, ZHU Shi-Yao, LIN Yu, ZENG Liang, PAN Qin-Min
Chin. Phys. Lett. 2000, 17 (3): 165-167 .  
Abstract   PDF(pc) (318KB) ( 347 )
A new method to measure an atomic wave function is discussed. It effectively solves the problem of an initially random phase of a travelling-wave laser beam. The relationship between the measured data and the atomic wave function is presented, and the wave function's reconstruction procedure is also analyzed.

Teleportation of Two Quantum States via the Quantum Computation
FENG Mang, ZHU Xi-Wen, FANG Xi-Ming, YAN Min, SHI Lei
Chin. Phys. Lett. 2000, 17 (3): 168-170 .  
Abstract   PDF(pc) (228KB) ( 442 )
A scheme of teleportation of two unknown quantum states via quantum computation is proposed. The comparison with the former proposals shows that our scheme is more in tune with the original teleportation proposal and the efficiency is higher. The teleportation of an unknown entangled state is also discussed.
Quantum Fluctuations of a Mesoscopic RLC Circuit in a Displaced Squeezed Fock State
WANG Xiao-Guang, PAN Shao-Hua,
Chin. Phys. Lett. 2000, 17 (3): 171-173 .  
Abstract   PDF(pc) (177KB) ( 467 )
Starting from the equation of motion for a circuit including resistor, inductor and capacitor (RLC), we study the quantum fluctuations of charge and magnetic flux of a mesoscopic RLC circuit in a displaced squeezed Fock state. It is found that the fluctuations of charge and magnetic flux do not depend on the displacement parameter and there exist squeezing effects between them. We also show how to generate the displaced squeezed Fock state in the RLC circuit.
Quantum Fluctuation in Thermal Vacuum State for Mesoscopic LC Electric Circuit
FAN Hong-Yi, LIANG Xian-Ting
Chin. Phys. Lett. 2000, 17 (3): 174-176 .  
Abstract   PDF(pc) (177KB) ( 565 )
We consider the quantization of LC (inductance-capacitance) circuit at a finite temperature T as any practical circuits always produce Joule heat except for superconductivity. It is shown that the quantum mechanical zeropoint fluctuations of both charge and current increase with upgoing T. Thermal field dynamics is used in our discussion.
Statistical Entropy of Three-Dimensional Spherical Spacetime
WANG Bin, SU Ru-Keng, FENG Shi-Xiang
Chin. Phys. Lett. 2000, 17 (3): 177-179 .  
Abstract   PDF(pc) (209KB) ( 441 )
By means of conformal field theory, we have related the degrees of freedom of microstates to the entropy of three dimensional charged black hole as well as the entanglement entropy of three-dimensional De Sitter spacetime. We have shown that the degrees of freedom of the conformal theory responsible for the entropy represent states on the horizon and localized in physical spacetime.
Symmetry Breaking in Finite Volume
LIU Chuan
Chin. Phys. Lett. 2000, 17 (3): 180-181 .  
Abstract   PDF(pc) (212KB) ( 397 )
Spontaneous symmetry breaking is a cooperative phenomenon for systems with infinitely many degrees of freedom and it plays an essential role in quantum field theories. Lattice O(N) model is studied within the Hamiltonian approach using an adiabatic approximation. It is shown that the low-lying spectrum of the system in the broken phase can be understood by using the adiabatic, or Born-Oppenheimer approximation, which turns out to become an expansion in the inverse power of volume. In the infinite volume limit, the symmetry is broken while in the finite volume the slow rotation of the zero-momentum mode restores the symmetry and gives rise to the rotator spectrum, which has been observed in realistic Monte Carlo simulations.

ΞΩ and Ξ*Ω Dibaryons in SU(3) Chiral Quark Model
LI Qiang-Bing, SHEN Peng-Nian, ,
Chin. Phys. Lett. 2000, 17 (3): 182-184 .  
Abstract   PDF(pc) (224KB) ( 373 )
The binding energy of the six quark system with strangeness s =-5 is investigated by the SU(3) chiral constituent quark model. The single Ξ*Ω channel calculation with spin S = 0 and the coupled ΞΩ - Ξ*Ω channel calculation with spin S = 1 are considered. It is shown that in the spin S = 0 case, the binding energy of Ξ*Ω is ranged from 80.0 to 92.4 MeV, while in the S = 1 case, the additional Ξ*Ω channel increases the binding energy of ΞΩ to a range of 26.2 - 32.9MeV.

Ground-State Properties of Z = 59 Nuclei in the Relativistic Mean-Field Theory
ZHOU Yong, MA Zhong-Yu, CHEN Bao-Qiu, LI Jun-Qing,
Chin. Phys. Lett. 2000, 17 (3): 185-187 .  
Abstract   PDF(pc) (277KB) ( 785 )
Ground-state properties of Pr isotopes are studied in a framework of the relativistic mean-field (RMF) theory using the recently proposed parameter set TM1. Bardeen-Cooper-Schrieffer (BCS) approximation and blocking method is adopted to deal with pairing interaction and the odd nucleon, respectively. The pairing forces are taken to be isospin dependent. The domain of the validity of the BCS theory and the positions of neutron and proton drip lines are studied. It is shown that RMF theory has provided a good description of the binding energy, isotope shifts and deformation of nuclei over a large range of Pr isotopes, which are in good agreement with those obtained in the finite-range droplet model.

Breakup of 33.4MeV/u 17N on a 9Be Target
HUA Hui, JIANG Dong-Xing, LI Xiang-Qing, QIAN Tao, WU He-Yu, JIN Gen-Ming, ZHAN Wen-Long, DUAN Li-Min, XIAO Zhi-Guang, GUO Zhong-Yan, LI Zu-Yu, WANG Hong-Wei, WANG Su-Fang
Chin. Phys. Lett. 2000, 17 (3): 188-190 .  
Abstract   PDF(pc) (248KB) ( 589 )
Correlation measurements of neutrons and fragments have been performed in a reaction of 33.4MeV/u 17N on a 9Be target. Energy spectra of n and nitrogen fragments were obtained at different angles. Based on the nuclear diffraction dissociation model, the measured energy spectra and the neutron angular distributions were reproduced quite well assuming that 17N was composed of 16N and n or 15N and 2n interacting with the nonlocal separable potential. The satisfactory agreement between the theoretical calculations and the experimental data shows that the contribution of Coulomb dissociation is negligible in the reaction concerned.
Spin-Exchange Collisions of the Ground State of Cs Atoms in a High Magnetic Field
FU Li-Ping, LUO Jun, ZENG Xi-Zhi
Chin. Phys. Lett. 2000, 17 (3): 191-193 .  
Abstract   PDF(pc) (228KB) ( 537 )
Cs atoms were optically pumped with a Ti:sapphire laser in a magnetic field of 1.516T. Steady absorption spectra and populations of Zeeman sublevels of the ground state of Cs in N2 gas at various pressures (5, 40, and 80 Torr) were obtained. The results show that in a high magnetic field, the combined electron-nuclear spin transition (flip-flop transition), which is mainly induced by the collision modification δa( J . I ) of hyperfine interaction, is an important relaxation mechanism at high buffer-gas pressures.
Theoretical Simulation of the Transmission Spectra of Fe and Ge Plasmas
YAN Jun, LI Jia-Ming,
Chin. Phys. Lett. 2000, 17 (3): 194-196 .  
Abstract   PDF(pc) (249KB) ( 459 )
Using the detailed configuration accounting with the term structures treated by the unresolved transition array model, we present a method to calculate the transmission spectra of hot dense plasmas. Due to the fully relativistic treatment, incorporated with the quantum defect theory to calculate the atomic parameters of the huge number of configurations with high principal quantum number, we can study the opacities for any middle- and high-Z plasmas with much less computational efforts. We can also conveniently identify the dominant configurations and the detailed features of transition arrays, which are very helpful for the diagnostic of the plasma conditions. The accuracy of our theoretical model is tested by comparing the calculated transmission spectra of Fe and Ge plasmas with the bench mark experimental data.

Two Types of Mass Abundance Distributions for Anionic Carbon Clusters Investigated by Laser Vaporization and Pulsed Molecular Beam Techniques
ZHAI Hua- Jin, LIU Bing-Chen, ZHOU Ru-Fang, NI Guo-Quan, XU Zhi-Zhan
Chin. Phys. Lett. 2000, 17 (3): 197-199 .  
Abstract   PDF(pc) (273KB) ( 411 )
Two types of mass spectra for anionic carbon clusters C-n have been revealed using laser vaporization and pulsed molecular beam techniques. The less structured mass spectrum characteristic of the magic-numbers at n = 5, 8, 11, 15, and 17 is established at the early stage of the cluster formation process, namely, in the laser vaporization process. The more structured one is featured for a regular odd-even alternation and the magic numbers at n =10, 12, 16, 18, 22, and 28, and has been developed only after extensive clustering and qnenching processes, where low-energy electron attachment plays a vital role. Transition between these two types of mass spectra can be realized by controlling either the strength of the pulsed gas flow or the synchronism between the gas flow and the laser vaporization.

Effects of Detunings on Dynamically Induced Irreversibility in Coherently Driven Systems
HU Xiang-Ming, PENG Jin-Sheng
Chin. Phys. Lett. 2000, 17 (3): 200-202 .  
Abstract   PDF(pc) (255KB) ( 533 )
Effects of detunings on dynamically induced irreversibility is studied for coherently driven V systems in which there is no conventional source of irreversible population pumping. For atomic barium (γ12= 400 >> 1, where γ1 and γ2 are the rates of the spontaneous decay from the excited states 6s6p1P1 and 6s6p3P1 to the ground state 6s2 1S0, respectively), the strong irreversibility is found to lead to a maximum inversion of 0.77 [only 0.1 in Phys. Rev. Lett. 71 (1993) 4311]. The maximum population inversion requires relatively strong fields coupled respectively to two transitions, a disparity in two atomic decay rates, and the atom-field detunings of opposite signs. However, it is also shown that even in the cases where two detunings have the same sign, or where two decay rates are equal, population inversion takes place.

Analysis of Laser Diode Pumped Solid-state Laser Resonator by the Transform Circle Approach
SONG Feng, ZHANG Guang-Yin, XU Jing-Jun, ZHANG Chao-Bo
Chin. Phys. Lett. 2000, 17 (3): 203-205 .  
Abstract   PDF(pc) (199KB) ( 387 )
The typical laser characteristics of a laser diode pumped solid-state laser with a Z-type resonator structure are analyzed by the transform circle approach. Laser waists change with the thermal focus length of the lasing medium so that the output power becomes unstable. In particular, there is a very unstable operation region when the pump power is of medium magnitude. A method is put forward to avoid this situation.
Fourth-Order Interference on Polarization Beats with Phase-Conjugation Geometry
ZHANG Yan-Peng, SUN Li-Qun, TANG Tian-Tong, ZHANG Lu, FU Pan-Ming
Chin. Phys. Lett. 2000, 17 (3): 206-208 .  
Abstract   PDF(pc) (277KB) ( 492 )
The effect of fourth-order coherence on ultrafast modulation spectroscopy (UMS) with phase-conjugation geometry (PCUMS) in a cascade three-level system is investigated using chaotic and phase-diffusion models. It has been found that the modulation terms of the beat signal depend on the second-order coherence function, and different stochastic models of the laser field affect only the fourth-order coherence function. The difference between the PCUMS and UMS is discussed from a physical viewpoint.

Thermal Lattice Boltzmann Model for Compressible Fluid
SUN Cheng-Hai
Chin. Phys. Lett. 2000, 17 (3): 209-211 .  
Abstract   PDF(pc) (198KB) ( 516 )
We formulate a new thermal lattice Boltzmann model to simulate compressible flows with a high Mach number. The main difference from the standard lattice Boltzmann models is that the particle velocities are no longer a constant, varying with the mean velocity and internal energy. The proper heat conduction term in the energy equation is recovered by modification of the fluctuating kinetic energy transported by particles. The simulation of Couette flow is in good agreement with the analytical solutions.
Space-Charge-Limiting Current of a Relativistic Electron Beam Propagating in a Rippled- Wall Waveguide
QIAN Bao-Liang, LEI Yin-Zhao, LIU Yong-Gui, LI Chuan-Lu
Chin. Phys. Lett. 2000, 17 (3): 212-214 .  
Abstract   PDF(pc) (219KB) ( 618 )
A fluid model is used to derive the space-charge-limiting current of a relativistic electron beam drifting in a rippled-wall cylindrical waveguide. It is found that an enhancement of the space-charge-limiting current is found as long as optimum values of the ripple wavelength and amplitude are chosen. However, a very small ripple wavelength of the waveguide may reduce the space-charge-limiting current rapidly. The result should be of interest to the operation of backward-wave oscillators.

Calculation of Defects in Silicon by a New Tight-Binding Model
PEI Min, WANG Wei, PAN Bi-Cai, , LI Yong-Ping,
Chin. Phys. Lett. 2000, 17 (3): 215-217 .  
Abstract   PDF(pc) (255KB) ( 400 )
The structural and electronic properties of monovacancy, divacancy defects within crystalline silicon have been investigated systematically using a new tight-binding model with a 216-atom supercell. The formation energies and energy levels of all the defect configurations are carefully calculated. The results show that atoms nearer to the defects naturally contribute to gap states more, and are comparable with the experimental values.
Temperature Coefficient of Sound Velocity of Perovskite-Enstatite and Lateral Thermal Heterogeneity in Earth’s Lower Mantle
GONG Zi-Zheng, XIE Hong-Sen, JING Fu-Qian, LIU Yong-Gang, GUO Jie, XU Jian,
Chin. Phys. Lett. 2000, 17 (3): 218-220 .  
Abstract   PDF(pc) (263KB) ( 362 )
Using the differences of sound velocity and temperature on the Hugoniot and isoentropic state, the temperature coefficients of sound velocity of perovskite-enstatite under high pressure were obtained. For compressional, shear and bulk wave velocities, their temperature coefficients decrease from 0.386, 0.251, 0.255m/(s.K) at 40 GPa to 0.197, 0.131, 0.162m/(s.K) at 140 GPa, respectively. Extrapolating these to zero pressure results in (∂K/∂T)0 = -0.0279 GPa.K-1, which is consistent very well with the value got by hydrostatic pressure experiment. On the basis of our data, we conclude that the compressional wave velocity anomaly of 0.1-0.2% in the deep lower mantle and 2% in the D" region would imply lateral thermal heterogeneity with amplitude of 53-106K and 1066K in these regions, respectively.
Growth of Biaxially Textured Yttria-Stabilized Zirconia Thin Films on Si(111) Substrate by Ion Beam Assisted Deposition
MU Hai-Chuan, REN Cong-Xin, JIANG Bing-Yao, DING Xing-Zhao, YU Yue-Hui, WANG Xi, LIU Xiang-Huai, ZHOU Gui-En, JIA Yun-Bo
Chin. Phys. Lett. 2000, 17 (3): 221-223 .  
Abstract   PDF(pc) (289KB) ( 633 )
The (001) oriented yttria-stabilized zirconia (YSZ) films with in-plane biaxial texture have been deposited on Si(111) substrates by ion beam assisted deposition at ambient temperature. The effects of ion/atom arrival rate ratio (R=(Ar+O+2)/ZrO2) and incident angle of bombarding ion beam on the film texture development were investigated. It was found that the in-plane biaxial texture of the films was improved gradually with increasing ion/atom arrival rate ratio R up to a critical value 1.9, but it was degraded with the further increase of R. The optimal in-plane biaxial texture, whose full width at half maximum of the (111) ø-scan spectrum is 14°, can be obtained at R=1.9 and incident angle of 55°. For a fixed R, the optimal crystallinity and in-plane biaxial alignment of the YSZ films did not appear at the s,ame incident angle and showed an opposite variation with the change of the incident angle from 51°to 55°C-axis alignment (perpendicular to substrate surface) does not show any substantial variation with the change of incident angle within the range of 47°– 56°.

Microstructures of GaN Buffer Layers Grown on Si(111) Using Rapic Thermal Process Low-Pressure Metalorganic Chemical Vapor Deposition
CHEN Peng, SHEN Bo, ZHU Jian-Min, CHEN Zhi-Zhong, ZHOU Yu-Gang, XIE Shi-Yong, ZHANG Rong, HAN Ping, GU Shu-Lin, ZHENG You-Dou, JIANG Shu-Sheng, FENG Duan Z. C. Huang*
Chin. Phys. Lett. 2000, 17 (3): 224-226 .  
Abstract   PDF(pc) (454KB) ( 569 )
Microstructures of GaN buffer layers grown on Si (111) substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope (AFM) and a high-resolution transmission electron microscope (HRTEM). AFM images show that the islands appear in the GaN buffer layer after annealing at high temperature. Cross-sectional HRTEM micrographs of the buffer region of these samples indicate that there are bunched steps on the surface of the Si substrate and a lot of domains in GaN misorienting each other with small angles. The boundaries of those domains locate near the bunched steps, and the regions of the film on a terrace between steps have the same crystal orientation. An amorphous-like layer, about 3nm thick, can also be observed between the GaN buffer layer and the Si substrate.

Giant Hall Effect of Fe45.51(Al2O3 )54.49 Nano-granular Film
XU Qing-Yu, NI Gang, SANG Hai, DU You-Wei
Chin. Phys. Lett. 2000, 17 (3): 227-229 .  
Abstract   PDF(pc) (268KB) ( 542 )
A series of Fe45.51(Al2O3 )54.49 nano-granular films were prepared using ion-beam sputtering technique. A saturated hall resistivity of about 12.5μΩ.cm at room temperature was observed. The transmission electron microscopy image showed that very small Fe particles of smaller than 1 nm are embedded in Al2O3 matrix, and connected into network. The measured ρ - T curve indicated that this giant Hall effect may originate from the percolation phenomenon. With different annealing temperature (TA) up to 300oC, the saturated Hall resistivity decreased only a little. The good thermal stability of Fe45.51(Al2O3 )54.49nano-granular Films showed potential application for magnetic sensor.

Constraint for the Existence of Ellipsoidal Vesicles
XIE Yu-Zhang
Chin. Phys. Lett. 2000, 17 (3): 230-232 .  
Abstract   PDF(pc) (180KB) ( 336 )
Under the spontaneous curvature model of lipid bilayers, the constraints for the existence of equilibrium axisym-metric oblate and prolate ellipsoidal vesicles are obtained from the general shape equation. They degenerate either to the constraint for the existence of a spherical vesicle or to that of a circular cylindrical vesicle given by Ou-Yang and Helfiich [Phys. Rev. Lett. 59 (1987) 2486; 60(1988)120; Phys. Rev. A 39 (1989) 5280].
Nonlinear Density Enhancement of 3He in the Sun’s Central Core
DU Jiu-Lin
Chin. Phys. Lett. 2000, 17 (3): 233-234 .  
Abstract   PDF(pc) (153KB) ( 394 )
A flow velocity field that has a “sink” drives the core 3He nuclear reaction diffusion system to instability to jump from the original state to the new one, in which the total amout of 3He is enhanced. This alters the original competition between pp I and pp II +pp III chains, and thus potentially suppresses the production of both the 7Be and 8B neutrino fluxes.
27 articles