For the nonlinear wave equation with quartic polynomial potential, bifurcation, bi-instability and solitary waves are investigated. An area principle based on the bifurcation diagram is found for the existence of bright and dark solitary waves and shock waves. The simple forms of solitary wave solutions are given by an approximate analytic method.

We construct a new kind of three-mode charge-related entangled state |q,k;n >_θ in three-mode Fock space, which possess the completeness relation and orthogonal property. It can describe when photons emitted by two energy levels simultaneously are absorbed by the third energy level. The relation between |q,k;n >_θ and the tripartite entangled state |q,k;n >_θ [Chin. Phys. Lett. 18 (2001) 1301] is pointed out.

We propose a theoretical scheme for any-to-any multi-user quantum key distribution on a passive optical network with ordered N Einstein-Podolsky-Rosen pairs. This scheme is safe and more efficient than those with single photons. Its efficiency approaches 100% in the limit that the number of pairs used in eavesdropping check becomes negligible. It also has high capacity and is convenient for users.

We study the Wentzel-Kramers-Brillouin (WKB) approaximation for dynamic systems with kinetic couplings in entangled state
representations. The result shows that the kinetic coupling will affects the position of classical turning points where the condition of using the WKB approximation breaks down. The modified WKB approximation formula is derived in the entangled state representation, for example, the common eigenvector of relative coordinate and total momentum of two particles. The corresponding Bohr-Sommerfeld quantization rule is also derived.

A new kind of crisis, which is marked by a sudden change of a strange repeller, is observed in an electronic relaxation oscillator. Firstly, by its simplified piecewise linear model, we show analytically that a strange repeller appears after a hole-induced crisis, and that the fractal dimension of the strange repeller and the averaged lifetime of the iterations in the region occupied by the original attractor suddenly change at the critical parameter value when the repeller disappears. Our numerical investigation convinces us that the corresponding phenomenon can be found in the original electronic relaxation oscillator.

A new prediction technique is proposed for chaotic time series. The usefulness of the technique is that it removes some false neighbouring points which are not suitable for the local estimation of the dynamics systems. We use a feedforward neural network to approximate the local dominant Lyapunov exponent, and choose the neighbouring points by the exponent. The model is tested for the convection amplitude of the Lorenz model, and the results indicate that this prediction technique can improve the prediction of chaotic time series.

The sine-Gordon equation is solved in a laboratory reference using the method of Darboux transformation. Using the Liouville theorem, explicit expressions of the single soliton solution and the breather solution are derived from the Darboux matrix in the case of null spectral parameter.

We apply non-Abelian transport theory to a low- temperature case, and discuss the colour electric dynamics of cold-dense quark matter at large chemical potential. Finally, at leading logarithmic accuracy, the color conductivity dependence on chemical potential is obtained.

The on-line time differential perturbed angular correlation technique has been developed for the first time. The quadrupole interaction of ¹⁹F in Cd was measured.

We present the experimental isotopic distributions of the ¹⁸N projectile fragmentation products Li, Be, B, and C in coincidence with neutrons, as well as the inclusive ones on ¹⁹⁷Au and ⁹Be targets. In the framework of the abrasion-ablation model, these distributions are calculated for various nucleon density distributions of the projectile. The comparison with the experimental isotopic distributions of the projectile-like fragments in coincidence with neutrons shows that the information on the nucleon density distribution of the ¹⁸N projectile can be extracted.

The quasi-elastic scattering of a secondary ⁶He beam (25 MeV/n) on a ⁹Be target has been measured for the first time by applications of a sophisticated tracking detector system. The angular distribution is reported. A phenomenological optical potential is obtained by fitting the experimental data, which encourages more accurate experiment measurements.

We have studied dilepton production in a chemically equilibrating quark-gluon matter produced at RHIC energies. We find that the dilepton yield is no longer a monotonously decreasing function of the initial quark chemical potential. therefore, the dilepton suppression may not be useful as a signature for quark-gluon matter formation.

The transverse flow of positive charged kaons from heavy-ion collisions at intermediate energy is investigated within the framework of the quantum molecular dynamics model. The calculated results show that the experimental data are only consistent with the ones including the kaon mean-field potential from the chiral Lagrangian. This indicates that the transverse flow pattern of kaons is an useful probe of the kaon potential in a nuclear medium.

We study the decay time constants and light output of an 18 x 18 x 1 mm³ YAP (YAlO₃) crystal doped with cerium. The result shows that the light pulse is composed of fast and a slow components. The fast component has a decay time constant of 24.05±0.15 ns with an intensity of 81.57±0.97% and the slow one has a decay time constant of 87.67±2.49 ns with an intensity of 18.51±1.34%. The measured light output is 3608±80 photoelectrons/MeV without the correction for the quantum efficiency of the photomultiplier tube XP2262B.

The opacity, and its Planck and Rosseland mean values, of the hot and dense Au plasma in local thermodynamics equilibrium are studied by the Monte Carlo method based on unresolved transition array (UTA) approximation. The average ion model and the Saha equation is used to determine the atomic level populations. The result gives a more detailed structure for frequency-dependent opacity than the popularly used super transition array or UTA in the photon energy range of 500 eV to 2000 eV. The Monte Carlo method can give a result better than that of UTA, with almost the same computation effort.

Using relativistic multi-configuration Dirac-Fock theory, we calculate the transition data of 3d_j-nf_j' (n = 5,6,7) for the M-shell from an Ni-like Au ion to an As-like Au ion by the GRASP programme with the core-polarization, quantum electrodynamical effect and Breit correction. Based on the present calculation results and the experiment of Xingguang-II laser facilities, the average distribution of ionic charge and the ionizability have been derived. The average ionization degree of Au plasma Z^* is 49.06±0.5, which is comparable with the result of the Lawrence Livemore National Laboratory.

We propose one-dimensional (1D) and two-dimensional (2D) arrays of magnetic surface microtraps for cold alkali atoms using some arrays of current-carrying wires and calculate the spatial distributions of magnetic fields from the 1D and 2D arrays of current-carrying wires. The field gradients and curvatures from a single magnetic microtrap are analysed, and some interesting and periodic magnetic-well microstructures are found. The result shows that the magnetic-field gradient greater than 2.4 x 10⁵G/cm and the field curvature greater than 4.05 x 10⁸G/cm² can be generated in our array of magnetic microraps, which can be used to realize the 1D and 2D arrays of Bose-Einstein condensations (or 1D and 2D arrays of Bose clusters) by rf-induced evaporative cooling, and then to form 1D and 2D atomic magnetic lattices, even to prepare 1D and 2D photonic crystals.

A new-style discharge tube for a metal vapor laser has been designed and built. SrBr₂ was successfully used to replace metal Strontium as a working medium, and multi-line laser oscillations from resonance to metastable transition of strontium atoms (6.45μm), ions (1.03μm/1.09μm) and from strontium ion recombination (416.2 nm/430.5 nm) have been obtained through longitudinal pulsed discharge. The problem of an incompatibility reaction between metallic strontium and the discharge tube in the strontium vapor laser was solved. Some proposals are presented for further developments of strontium halide lasers.

We report on an efficient blue light generation in a periodically poled LiTaO₃ by the frequency tripling of a quasi-continuous 1342 nm Nd:YVO₄ laser. The period of the sample was 14.778μm. Blue light with an average power of 138 mW was generated from a 18 mm long crystal in a single-pass process under an averaged fundamental power of 713 mW. The internal conversion efficiency was 19.3%.

The principle of charge transfer agents was investigated experimentally. There is a compensation effect between triethanolamine (TEA) and diphenyliodonium hexafluorophosphate (DPI) in the polymerization process of photopolymer. The experimental results illustrated that TEA has a stronger effect in the initial stage of exposure, and DPI has a stronger effect during the propagation stage of the polymerization process. We explain the main contributions of DPI in the superadditive photopolymer kinetics that results in an obvious increase of sensitivity.

The gradient elastic constitutive equation incorporating the second gradient of the strains is used to determine the monochromatic elastic plane wave propagation in a gradient infinite medium and thin rod. The equation of motion, together with the internal material length, has been derived. Various dispersion relations have been determined. We present explicit expressions for relationship among various wave speeds, wavenumber and internal material length.

A statistical method is introduced to deal with the two-electron energies of a configuration in the detailed term accounting (DTA) approximation for the spectral line absorption in the radiative opacity of laser-produced plasmas in local thermodynamics equilibrium. The relativistic Hartree-Fock-Slater self-consistent field average atom model is used to select the reference ion with most-probability and providing basically atomic data. In this way, fully frequency-dependent and spectral resolved opacity for heavy element can be obtained readily for the primary design of radiation transfer in the inertial confinement fusion simulation. Opacities of Au plasmas are given.

We experimentally investigate the generation of hot electrons from the interaction of a moderate-intensity (10¹⁶W/cm²) pre-pulsed-free femtosecond laser (6 mJ, 120 fs, at 744 nm) with a solid target. The temperature of the hot electrons is inferred from the hard x-ray ( > 30 keV) continuum. The measured hard x-ray continuum is fitted by the Maxwellian distribution with two hot-electron temperatures of 45 and 85 keV. Electrons with the lower temperature were accelerated by “vacuum heating”. However it is necessary to carry out an accurate numerical simulation to explain the generation of hot electrons at higher temperature.

The quasi-static magnetic fields created in the interaction of the relativistic laser pulses with under-dense plasmas have been investigated by three-dimensional particlein-cell (PIC) simulation. The relativistic ponderomotive force can drive an intense electron current in the laser propagation direction, which is responsible for the generation of a helical magnetic field. The axial magnetic field results from a difference beat of wave-wave, which drives a solenoidal current. In particular, the physical significance of the kinetic model for the generation of the axial magnetic field is discussed.

We have discussed the quantum mechanical effects for the energetic charged particles produced in D - He³ fusion reactions. Our results show that it is better to use the proper coulomb logarithm at the high-energy end in describing the thermalization process, because the quantum mechanical effects on the coulomb logarithm are not negligible, based on an assumption of binary collision.

As part of the programme to develop a free-standing thin-film filter for soft x-ray optics applications, stress anisotropy in molybdenum films deposited by dc circular planar magnetron sputtering has been studied by off-normal x-ray diffraction as a function of sputtering argon gas pressure over a range of 0.8-1.5 Pa. The stresses are found to be more compressive in the center area than in the edge area, and more compressive in the tangential direction than in the radial direction. The highest stress anisotropy exists in the film deposited at 1.5 Pa gas pressure. Annealing the films in vacuum is effective in reducing both the tensile stress and stress anisotropy in the tensile stressed films.

ZnS quantum dots (QDs) synthesized in water and ethanol solutions were coated with polystyrene (PS) and SiO₂ shells, respectively. The band edge emission was enhanced by nearly five times after PS coating and about 13 times after SiO₂ coating, because the surface trap states were removed. From the photoluminescence properties of ZnS QDs coated with PS and SiO₂ shells we have detected the improvement of thermal stability. This is due to the fact that the surface passivation can prevent the further growth of the ZnS QDs and the diffusion of oxygen on the surface of ZnS QDs during thermal oxidation.

We develop a numerical model to investigate the localization of surface-exciton polaritons in the presence of random roughness and spatial dispersion. It is found that the localization occurs in a limited frequency range near the maximum frequency of surface-exciton polaritons. The decaying length in the extended region is much larger than that in the localized region. The localization of surface-exciton polaritons is due to the destructive interference between waves scattered from the rough surface.

We study the energy levels of an electron (or hole) polaron in a parabolic quantum well structure, including the spatial dependence of the effective mass. We also consider the two-mode behaviour of longitudinal optical phonon modes of the ternary mixed crystals in the structure, in the calculation of the effect of the electron-phonon interaction. We calculate the ground state, the first excited state and the transition energy of an electron (or hole) in the GaAs/Al_xGa_1-xAs parabolic quantum well structure. The numerical results show that the electron-phonon interaction obviously affects the energy levels of the electron (hole), which are in agreement with experimental results.

Low-lying states of a vertically coupled three-layer quantum-dot system are studied. Each layer contains one electron, and the tunnelling of electrons between layers is neglected. Effects of the interlayer separation d and the external magnetic field B are evaluated by numerical calculations. In the strong coupling case (i.e., d is small), as in a single dot, transitions of the angular momentum L of the true ground states occur when B increases, whereas in the weak coupling case the transition does not occur and the L remains zero. Furthermore, it is found that the variation of d may also induce the L-transition. As a result, a phase diagram of L of the true ground state is given in the d - B plane.

We investigate the dynamics of two interaction electrons confined to one-dimensional quantum dot array in an ac electric field. We find that initially localized electrons will maintain localized in the absence of Coulomb interaction if the ratio of the ac field magnitude to the frequency is a root of the ordinary zero-order Bessel function. In contrast to the case without Coulomb interaction, no matter what the value is, the electrons are delocalized and the delocalization effect depends on the ratio U/ω and eaE/ω, where U is the strength of Coulomb interaction, a is the lattice constant, and E and ω are the ac field amplitude and frequency, respectively.

The zero-point energy of mesoscopic nonlinear inductance-capacitance (L-C) circuit is obtained by making use of the variation method. This is somewhat less than that of simple harmonic oscillator.

We investigate the period halving of persistent currents (PCs) of non-interacting electrons in isolated mesoscopic Möbius ladders without disorder, pierced by Aharonov-Bohm flux. The mechanisms of the period halving effect depend on the parity of the number of electrons as well as on the interchain hopping. Although the data of PCs in mesoscopic systems are sample-specific, some simple rules are found in the canonical ensemble average, for example, all the odd harmonics of the PCs disappear and the signals of even harmonics are non-negative.

In a self-consistent mean-field treatment of the two-dimensional t-t'-J model, we theoretically examine the coupling of in-plane quasi-particles to the antiferromagnetic spin fluctuations in high-T_c superconductors, which renormalizes the fermionic self-energy. We reproduce the characteristic peak-dip-hump structure observed not only in angle-resolved photoemission spectroscopy, but also in supperconductor-insulator-normal metal junction and scan tunneling microscopy experiments. We consider the evolution of this structure with doping. It is shown that this kind of coupling can account for many anomalous properties of high-T_c superconductor in superconducting states.

The magnetic properties and magnetoresistance effect of
YMn₆Sn_6-xCr_x (x = 0-0.8) compounds have been experimentally studied by magnetic properties and resistivity measurements in the applied field range 0-5 T. The compound (x = 0.8) displays the ferromagnetic behaviour, while the compounds (x = 0-0.4) display the antiferromagnetic behaviour in the whole ordering temperature range. The compounds (x = 0.5, 0.6) experienced a transition from an antiferromagnetic state to ferromagnetic one with increasing temperature. The compound with x = 0.8 is rapidly saturated in the lower magnetic field with saturation magnetization of 35.92 emu/g. The compounds (x = 0-0.6) display a field induced metamagnetic transition, and the threshold fields decrease with increasing Cr content. The cell-volume V of compounds (x = 0-0.8) increases, and the ordering temperature decreases with the increasing Cr content. A large magnetoresistance effect was observed for the compounds (x = 0.4, 0.5), and the maximum absolute value at 5 K are 32% and 24% under 5 T for x = 0.4 and x = 0.5, respectively.

The stress-impedance (SI) effect has been observed in as-cast and high-current-density electropulsing annealed Fe_73.5Cu₁Nb₃Si_13.5B₉ ribbons. Large SI ratios of -35% and 25% have been obtained in high-current-density electropulsing annealed samples but not in as-cast samples. The SI effect changes drastically with the density of annealing current and the longitudinally applied stress during the annealing process. The effective permeability has been shown to be responsible for the SI effect.

We have studied the two-state random decoherence model of the ₁₅ system (Phys. Rev. Lett. 84 (2000)3458) with the ‘partial tracing of the environment’method. The linearity relation between the averaged decoherence time and the random dipolar interaction amplitude is verified. The distribution function of decoherence time spreads more widely as the amplitude of the random field is decreased, hence it is difficult to define a decoherence time for the system.

Nanogranular Fe_0.35/(In₂O₃)_0.65 film with complex magnetic structure were prepared by the rf sputtering method. An extra-large magnetoresistance up to 506% was obtained at 2.2 K, which is two orders of magnitude larger than that obtained at room temperature. This is related to the interaction with the impurities influencing the local magnetization, which is quite different from spin-dependent tunneling effect at room temperature. The interspacing Fe atoms dispersed in the In₂O₃ matrix play an important role in the transportation properties of carriers at low temperature.

Numerical modeling of velocity and temperature fiels in high-temperature KNbO₃ melt of a loop-shaped Pt wire heater is carried out by using the commercial computational code ANSYS for the mathematical solution of the governing equations. Based on the experimental boundary conditions and the Boussinesq approximation, the numerical modeling of a steady and two-dimensional model is applied to study the process under consideration of the buoyancy-driven convection condition. The result is compared with the previous experimental and theoretical data obtained in our laboratory, and the former is in agreement with the latter. Thus a theoretical guide for reasonable growth conditions is provided by studying in depth the real fluid flow effects in the crystal growth from the melt.

Contactless electroreflectance has been employed at room temperature to study the Fermi level pinning at undoped-n⁺ GaAs surface covered by 1.6 and 1.8 monolayer (ML) InAs quantum dots (QDs). It is shown that the 1.8 ML InAs QDs moves the Fermi level at GaAs surface to the valence band maximum by about 70 meV compared to bare GaAs, whereas 1.6 ML InAs on GaAs does not modify the Fermi level. It is confirmed that the modification of the 1.8 ML InAs deposition on the Fermi level at GaAs surface is due to the QDs, which are surrounded by some oxidized InAs facets, rather than the wetting layer.

By using n-butylamine as a carbon resource, carbon film is deposited on the p-n porous silicon (PS) surface with a radio-frequency glow discharge plasma system. Raman spectra and infrared reflection (IR) spectra of the carbon films indicate that there are amine-group and hydrogen atoms therein. The IR spectra of the passivated PS samples exhibit that the PS surfaces are mainly covered with Si-C,Si-N and Si-O bonds. Electroluminescece (EL) spectra show that EL intensity of the passivated PS diodes increases greatly and the blueshift of EL peak occurs compared with the diodes without treatment and both of them are stable while the passivated diodes are exposed to the air indoor. The I-V characteristics reveal that the passivated diodes have a smaller series resistance and a lower onset voltage. The influence of the carbon film passivation on EL properties of porous silicon has also been discussed. The results have proved that the carbon film passivation is a good way to enhance the PS luminescent intensity and stability.

Arrays of single crystalline gold nanowires were synthesized
electrochemically in porous polycarbonate membranes. The polycarbonate membrane was then removed to obtain freestanding nanowires for field emission measurements. The turn-on electric field strength for field emission is found to be lower than 2V/μm. The actual electric field that extracted electrons out of the gold nanowires is estimated to be about 10³ times higher than the field directly expected in the model of a parallel plate condenser. The availability of the field emission is therefore attributed to the strong electric field at the tips resulting from small curvature radius of the gold nanowires.

We simulate the {100}-oriented diamond film growth of chemical vapor deposition (CVD) under different models in C-H and C-H-Cl systems in an atomic scale by using the revised kinetic Monte Carlo method. The simulation results show that: (1) the CVD diamond film growth in the C-H system is suitable for high substrate temperature, and the film surface roughness is very coarse; (2) the CVD diamond film can grow in the C-H-Cl system either at high temperature or at low temperature, and the film quality is outstanding; (3) atomic Cl takes an active role for the growth of diamond film, especially at low temperatures. The concentration of atomic Cl should be controlled in a proper range.

A new configuration of carbon nanotubes (CNTs) has been discovered in our laboratory and their surfaces are fully covered with nano-sized node-like structures. The node structures have almost the same size of 40-50 nm. We refer to this material as the nodular carbon nanotubes (NCNTs). Field emission scanning electron microscopy shows that after a hydrogen plasma process in our homemade plasma equipment, the common carbon nanotubes were changed into NCNTs. The experimental result demontrates that this material has good field emission characteristics, low threshold field, stable and suitable emitting current, especially for the emission site density up to the order of 10⁶cm^-2.

We study the rotation of the polarization plane for a ray of
electromagnetic radiation propagating in the gravitoelectromagnetic field caused by a rotating massive object with the quadrupole moment. The effect of the quadrupole moment on the gravitational Faraday rotation is investigated. It is found that the gravitational Faraday effect of the quadrupole moment is negligible for Kerr black holes, but this effect is important for rapidly rotating neutron stars.

The abundance enhancements of heavy ions Ne, Mg, Si and Fe in impulsive solar energetic particle (SEP) events are explained by a plasma acceleration mechanism. In consideration of the fact that the coronal plasma is mainly composed of hydrogen and helium ion, we think that the ion-ion hybrid wave and quasi-perpendicular wave can be excited by the energetic electron beam in impulsive solar flares. These waves may resonantly be absorbed by heavy ions when the frequencies of these waves are close to the second harmonic gyrofrequencies of these heavy ions. This requires the coronal plasma temperature to be located in the range of T ～ (5 - 9) x 10⁶ K in impulsive solar flares and makes the average ionic charge state of these heavy ions in impulsive SEP events be higher than the average ionic charge state of these heavy ions in gradual SEP events. These preheated and enhanced heavy ions can successively and stochastically be accelerated by Alfvén turbulence and then form a power-law distribution in impulsive SEP events.