An approximate instantaneous eigenstate is presented for the many-spin system possessing the anisotropy exchange interaction in a strong magnetic field by the perturbation method. Based on the instantaneous eigenstate, the Berry phase of this state is worked out. Furthermore, the effect of the anisotropy exchange interaction on the Berry phase of the state for the many-spin system is studied.

The squeezing operator S⁽ⁿ⁾ and the corresponding squeezed state |0>_s for n-mode quadrature operators are founded. The normally ordered form of S⁽ⁿ⁾ is derived by means of the technique of integration within an ordered product of operators. Moreover, the existence of higher-order squeezing for n-mode quadratures in the State |0>_s is demonstrated.

A flashing correlation ratchet model is proposed, in which the transport of Brownian particles driven by additive colored noise of Ornstein-Uhlenbeck type in a flashing ratchet is studied by Monte Carlo simulation. The stationary current vs the noise strength and the correlation time is obtained and analyzed. For a fixed rate of potential flashing, the novel phenomena of current reversal and reentry occur. The conditions for the occurrence of these phenomena are found. The influence of the flipping rate is also discussed. This finding might be relevant to the fact that the protein motors with similar structure can move in opposite directions on the same kind of microtubule.

A new prototype atomic fountain clock working in the micro-gravity environment is proposed. The successive Ramsey interactions of cold atoms and oscillatory field are realized by means of computer-controlled periodic motion of oscillatory field while the cold atoms stay still relatively in the prototype. Preliminary analyses in comparison with the atomic fountain clock working on the ground show that higher stability is obtainable in the prototype.

Standard evolution equation including virtual graphs is derived in time ordered perturbative theory. We propose a new cutting rule in deep inelastic scattering processes, which provides a useful tool for discussing the connections among the real and virtual cut diagrams and better understanding of evolution equation.

Does an exotic 1^-+ hybrid candidate ρ (1405) in the vicinity of a₂ (1320) exist? It is worth to confirm this state in the process J/ψ → ρηπ at the BEPC (Beijing Electron-Positron Collider)/BES (Beijing Spectrameter). Considering ρ (1405), a₂ (1320) and a₀ (1450) overlap in this mass region, the three-state coupling structure mode is discussed by using the generalized moment analysis method. A series of moments for the mode and a criterion are given for confirming the exotic 1^-+ hybrid.

High-spin states in ⁸⁴Rb have been studied by using the ⁷⁰Zn (¹⁸O, p3n) ⁸⁴Rb reaction at a beam energy of 75MeV. The γ- γ coincidence, excitation function and ratios for directional correlation of oriented states were performed. A new level scheme was established in which the positive and negative parity bands have been extended up to 17⁺ and 17^- with excitation energy about 7MeV. The signature splitting and signature inversion of the positive parity yrast bands were observed and are discussed.

A general cascade package is used to handle the J/ψ and ψ production and absorption for different E_T bins in S-U and Pb-Pb collisions. We study the combined effect of nuclear absorption and final state interaction with co-movers on the J/ψ and ψ suppression. The experimental data of J/ψ production can be fitted for different E_T-bins in S-U collisions and for lower E_T-bins in Pb-Pb collisions. However, ψ data for high E_T-bins in both S-U and Pb-Pb collisions can not be explained.

Elastic recoil detection analysis technique with ΔE - E particle identification and Q3D momentum analysis has been developed to determine high resolution depth profiles in thin foils and multilayer systems. A depth resolution of 1.2nm was achieved at the surface of the samples using a high quality 100MeV ¹²⁷I beam. The method was applied to depth profile analysis of C/LiF multilayers, superconductor and GaN foil samples.

The production of heavy-flavor quark c(c) and b(b) in pp collisions is described under perturbative quantum chromodynamics framework, the extrapolation from hadron-hadron up to nucleus-nucleus collisions is based on geometrical model by taking into account the nucleus shadowing effect. We simulate the heavy quark production, the decay to dilepton and effects of detection and analysis technique of the pairs, and predict the muon rate and the invariant mass spectrum of dimuons that could be detected in forward region in Pb-Pb collisions at large hadron collider energies.

Correlated fission fragments from the reaction of 25 MeV/u ⁴⁰Ar+²⁰⁹Bi and their further correlation with a particles have been studied for peripheral and central collisions simultaneously. The excitation energy at scission deduced from postscission multiplicity is about 172.5 MeV. The fission timescale deduced from prescission multiplicity is about 4 x10^-21 s. Systematic analysis of the mass and energy distributions of fission fragments as a function of the initial temperature of hot fissioning nuclei reveals the existence of different fission behavior of hot nuclei formed in central and peripheral collisions. Experimental data demonstrate the change of fission behavior at T ～ 4MeV.

By using the time-independent formal scattering theoretical approach, we develop a nonperturbative quantum electrodynamics theory to describe high-order harmonic generation (HHG). This theory recovers the semi-classical interpretation of Corkum (Phys. Rev. Lett. 71 (1993) 1994) and gives the same phenomenological cutoff law. The HHG emission rate is expressed as an analytic closed form. We also discuss the connection between HHG and the above threshold ionization from the scattering viewpoint.

Electron-induced Zn ionization cross sections, which are scarce, have been obtained from measurement of K_α x-ray emission at energies from near threshold to 25keV. The influence of substrate of thin target on ionization cross sections has been corrected by using the bipartition model of electron transport. The experimental results are satisfactory as compared with empirical formula of Green and Cosslett.

ontinuous-wave radiation of 5W at 532nm was produced with an Nd:YVO₄/KTP intracavity frequency-doubled laser end-pumped by a diode-laser-array at pump power of 17.2 W, giving optical conversion efficiency of 29.1 %. The output power stability was measured to be better than 1.5% in short term operation. The pump-induced thermal lensing was also measured, showing good agreement with the performance of the laser.

In a homogeneously broadened laser model, we find a simple and general law for stable multimode operation, which shows a nonlinear cooperative relationship between the frequencies and intensities of laser modes.

Based on theoretical and experimental studies on the optical properties of long-period gratings (LPGs), an erbium doped fiber amplifier (EDFA) gain equalizer was fabricated by writing three long period gratings with designed properties in hydrogen-loaded standard singlemode fibers. The LPGs were written by a KrF excimer laser at 248nm with amplitude masks. The gain variation of ±3dB in the EDFA is reduced to ±0.3dB with a bandwidth of 30nm and the total insertion loss of the device is less than 0.3dB.

An electrically tunable optical fibre Mach-Zehnder interferometer is reported, based on the magnetostrictive effect. The period and peak wavelength of the interference spectrum can be electrically tuned to match the International Telecommunication Union's standard wavelength grid and so it is promising to be used in dense wavelength division multiplexing technology.

Analyses of the anisotropic behavior of a fiber composite plate from the laser-generated ultrasonic Lamb waveforms propagating in different directions are presented by employing wavelet transform techniques. The time-frequency representation plots of the waveforms clearly exhibit the anisotropic behavior of the composite plate. The plots also indicate that the waveform mainly consists of three or four lower-order Lamb wave modes, and other higher-order modes can be neglected in extracting elastic stiffness properties by comparison of theory with experimental waveforms. The group velocity of each mode is calculated according to the group delay and the source-receiver distance.

An electron heat transport model is given for studying laser-to-x-ray conversion of inertial confinement fusion. The electron heat flux is derived based on a non-Maxwellian electron distribution, and the behavior of the heat flux is discussed. The effect of the non-Maxwellian electron distribution on inverse bremsstrahlung heating rate and electron-ion heat transfer rate are also included in the present model. The simulation results show that the effects of the non-Maxwellian electron distribution on laser absorption efficiency, laser-to-x-ray conversion efficiency and electron temperature in the coronal region are important.

Raman spectra of layered ferroelectrics Sr_2+xBi_4-xTi_5-xNb_xO₁₈ (0 ≤ x ≤ 2) and Sr_2+xBi_4-xTi_5-xNb_xO₁₈ at room temperature in the range of 20-1000cm^-1 were investigated. Vibration modes were assigned with the internal mode approach. Two doping-induced structure phase transitions were observed at about x = 0.5 and 1.25 for Sr_2+xBi_4-xTi_5-xNb_xO₁₈, separately.

The binding energies of excitons bound to neutral donors in two-dimensional (2D) semiconductors within the spherical-effective-mass approximation, which are nondegenerate energy bands, have been calculated by a varia-tional method for a relevant range of the effective electron-to-hole mass ratio σ. The ratio of the binding energy of a 2D exciton bound to a neutral donor to that of a 2D neutral donor is found to be from 0.58 to 0.10. In the limit of vanishing σ and large σ, the results agree fairly well with previous experimental results. The results of this approach are compared with those of earlier theories.

A new practical equation is derived from the Miller-Abrahams theory for different site-energies, and the temperature-dependent conductivity of Fibonacci lattice is calculated by a real-space renormalization-group approach. It is shown that there exist two types of temperature-dependent conductivity at low- and high-frequencies. Furthermore, it is found that the low-frequency conductivity oscillates dramatically with temperature.

The crystal structure of spinel FeCr₂S₄, which shows a semiconductor-metal transition and paramagnetic-ferrimagnetic transition at T_c = 170K , was determined by x-ray powder diffraction. It is found that the spinel FeCr₂S₄ belongs to a normal spinel structure [Fe²⁺]_t[Cr³⁺₂]_oS₄. The result clearly shows that the spinel FeCr₂S₄ has neither mixed valence of Fe³⁺ and Fe²⁺ ions or Cr³⁺ and Cr²⁺ ions for a double-exchange magnetic interaction, nor a Jahn-Teller cation such as Cr³⁺. The spinels represent a distinct class of colossal magnetoresistance materials, with magnetic ordering driven by superexchange rather than double exchange.

A quantum well controller (QWC) consisting of a direct-gap/indirect-gap quantum well and a doping interface is proposed to control the dynamic operation of the Gunn active layer. Through the Monte Carlo simulation a new relaxation mode for this new device is found. The oscillation and amplification behavior of the Gunn active layer under the control of the QWC is investigated theoretically and experimentally. All work demonstrates the great control capacity of the QWC and provides a new way to improve the performance of semiconductor devices. A new oscillation diode made of the QWC and a Gunn active layer has been designed and fabricated. In the 8mm band the highest pulse output power of these diodes is 2.55 Wand the highest conversion efficiency is 18%.

Two kinds of alignment of two neighboring organic ferromagnetic chains are studied with Su-Schrieffer-Heeger Hamiltonian added by Hubbard repulsion and antiferromagnetic correlation between side radicals and main chain. The results show that interchain coupling makes the energy gap decreasing. The out-of-phase alignment of two chains is energetically preferred to the in-phase alignment and it is a more possible ferromagnetic structure if the oscillatory part of interchain coupling of the in-phase is small. The spin density and dimerization along the main chain are also discussed.

A coherent inverse Compton scattering (ICS) mechanism is used to get polarization properties of radio emission of pulsars. It is found that particles moving along a ring with radius θ' = l/(√3γ)simultaneously contribute via coherent ICS. The circular polarization can be easily gotten as well as linear polarization at the same time. Our theory releases the upper limit of Lorentz factor γ≤20 put by curvature radiation, and γ may take several thousands in ICS. firtherrnore, subpulse position angles do take diverse values, while mean position angle is associated with the projection of magnetic field lines. So it is natural to get commonly-seen S-shaped swing of mean position angles. Finally we present a simulation for position angle rotation, linear polarization, circular polarization of PSR1508+55, which means that the coherent ICS may be responsible for radio emission.

The vertical structure of the disk should be specified in order to compare the theoretical model with the observed spectrum of active galactic nuclei. All the existing calculations of vertical structure of the accretion disk were based on the standard model. In this paper the vertical structure of the slim disk is calculated, which may be suitable for wider ranges of parameters. The spectrum for higher accretion rate tends to the universal form F_v ∝ v^-1 and the universal cutoff energy, which is consistent with the self-similar solution for the case with a super-Eddington accretion rate.