We propose a scheme for testing the symmetrization postulate (SP) for phonons in an ion trap. In the scheme a two-level ion is trapped in a harmonic potential and driven by a laser beam tuned to the carrier. The violation of the SP is manifested by the probability that the ion makes a transition from the ground state to the excited state after an appropriate interaction time.

The original version of Einstein-Podolsky-Rosen paradox and the Klein paradox of Klein-Gordon equation are discussed to show the necessity of existence of antiparticle with its wave function being fixed unambiguously. No concept of “hole” is needed.

The radial parts of the gravitational, electromagnetic, neutrino, and massless scalar fields in Barriola-Vilenkin spacetime are transformed to the form of the Teukolsky-type master equation. The first quantum corrections to the entropy of the black hole due to the spin fields are calculated by using the brick wall model. It is shown that the contribution of any one of the spin fields is quadratically divergent at the event horizon and is proportional to the surface area of the event horizon.

Many systems can display a very short, rapid changing stage (quasi-discontinuous region) inside a relatively very long and slowly changing process. A quantitative definition for the “quasi-discontinuity” in these systems has been introduced. We have shown by a simplified model that extra-large Feigenbaum constants can be found inside some period-doubling cascades due to the quasi-discontinuity. As an example, this phenomenon has also been observed in Rose-Hindmash model describing neuron activities.

The excitation spectra for (Ξ12-Be) and (Ξ16-C) are obtained in the frame of a shell model. The experimental values of the ground state binding energies of the Ξ^- hyperon in (Ξ12-Be) and (Ξ16-C) are used to determine the well depth of the Ξ^-- nucleus potential. The information on the residual interaction is emphasized. It is found that the residual interaction does not have much effect on the spectra of the Ξ^--hypernucleus.

By using the semi-relativistic distorted-wave Born exchange method, electron impact cross sections for the Fe²³⁺line emission 3d_5/2 + 2p_3/2 are calculated. The calculation involves line formation by direct electron-impact excitation, radiative cascade, resonant excitation, and dielectronic recombination satellites with captured electron in the n ≥ 5 levels. The results show a good agreement with the recent measurements.

The autoionization distribution o f the triply excited double Rydberg states (TEDRS) 5d_5/2NLnl (N ≤ 2 2 ; n≤ 50; L, l < 4) of La has been investigated by using five-laser resonance excitation in combination with a method of sequential ionization by a pulsed electric field and a constant electric field. The experimental results exhibit that the La atoms in TEDRS predominantly single-autoionize to the ionic Rydberg states located in a few Rydberg manifolds. Furthermore, a difference of autoionization mechanisms between TEDRS above and those below the double ionization threshold is found.

Based on the detailed configuration accounting model(DCA), a method is developed to calculate the rate of the resonant photoionization(RP) in the average atom(AA) model. Using this method, the RP rates are calculated for an average ion and compared with DCA calculation. The comparison shows the reasonableness of the proposed method. The RP process is included in the AA rate equations and the numerical results show that RP can cause an additional ionization up to 10% or so in some cases.

We propose an approach to prepare GHZ(Greenberger, Horne, Zeilinger) states of an arbitrary multi-particle system in terms of Grover's fast quantum searching algorithm. The approach can be used to produce other entangled states with various degrees of entanglement.

Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti: sapphire laser was studied at various pulse durations and energies. The generated supercontinuum was greatly blue-broadened due to self-phase modulation in the plasma produced. The measured blue-broadening Δω is proportional to pulse intensity for fixed pulse duration, and values up to 0.7ω (ω being the original laser frequency) was obtained with a pulse energy of 9.5 mJ and minimum duration of 100 fs.

By using the molecular dynamics simulation, we have studied the dynamic behaviors of small energetic clusters deposited on the surface. We find that, at incident energy as low as1.0eV/atom, the structure of the cluster is destroyed and cluster atoms form an epitaxial layer above the surface. At high energy incidence, the site exchange between cluster atom and surface atom is observed. The effects of the cluster size and orientation are discussed.

We report the mass spectrometric investigation on fullerene derivatives C₆₀CH₂, C₆₀RH , C₆₀R₂(R = C₆H₅ CO-) and C₆₀O_n under the 308nm laser ablation. In the negative ion mass spectra of C₆₀CH₂, C₆₀R₂ and C₆₀O_n odd-numbered clusters C^-₅₇,C^-₅₅, C^-₅₃, C^-₅₁ are observed clearly in addition to the even-numbered fullerene fragment ions, while for the monoadduct C₆₀ RH,, odd-numbered species can not be detected. In the positive ion channel, the fragmentation patterns of the three derivatives are similar

Tunable amplitude squeezing around the D₂ line of cesium has been experimentally accomplished at room temperature in a quantum-well laser diode with light injection from a single-mode distributed Bragg-Reflector laser diode. While the master laser frequency is tuned, amplitude squeezing of the output light from the slave laser can be maintained at about 0.9dB throughout a tunable range of ~1.7GHz around the cesium D₂ line.

The spontaneous emission from a V-type three-level atom embedded in a two-band photonic crystal is studied. Due to the quantum interference between the two transitions and existence of two bands, the populations in the upper levels display some novel behavior: anti-trapping, population oscillation, and population inversion.

Pattern formation in azobenzene polymer film by degenerate four-wave mixing is reported. Island arrays with specific patterns are analyzed with scanning electron microscopy and polarizing optical microscopy. It is demonstrated that the control of photo-induced nanostructure sized micropattern in the nonlinear organic film is possible by using properly polarized writing beams with the total incident power exceeding a certain threshold.

We demonstrated experimentally the dependence of two-beam coupling on the incident pump intensity in our samples of doped LiNbO₃ crystals. Our results show that there is an optimum pump intensity for the signal beam amplification, which can be easily controlled by doping the LiNbO₃ crystal with suitable concentrations of Fe and damage-resistant dopants such as Mg, In, and Zn.

The shrinkage effect of polymer films, which was demonstrated in our photobleaching experiment, can be fitted approximately by an exponentially decaying function. After taking the shrinkage effect into account, the index profile of the polymer waveguide was determined to be a Fermi function with the help of the m-line method and the exact transfer matrix theory.

Device quality InAsP/InGaAsP strained multiquantum-well (MQW) structures are successfully grown by using gas source molecular beam epitaxy method. The grown MQW and InGaAsP quanternary alloy are characterized by using x-ray diffraction, room temperature photoluminescence measurements, confirming that optimum growth condition and high quality material have been obtained for device application. The grown laser structures are processed into ridge waveguide lasers. A threshold current as low as 16mA at 25°C for 300µm long device has been obtained. Temperature-dependent light-current measurement shows a characteristic temperature of 75 K.

Based on the results of total-energy calculations for embedded clusters using self-consistent-field X_α-scattered-wave method, we determined the tetragonal fine structure of K(Ta_0.56Nb_0.44)O₃, i.e., the equilibrium configuration of B-site cations (Ta and Nb) in the ferroelectric phase. Ta is found to have an off-center displacement of about 0.02Å along [001]. The off-center displacement of Nb is much larger than that of Ta, thus it makes a major contribution to the occurrence of the ferroelectric instability.

Electronic properties are investigated for three alumina polymorphs (corundum, Rh₂O₃ (II) and Pbnm perovskite), which are predicted as the stable structures under different pressure range, by means of the first-principles molecular dynamics method within local density functional framework. The similarity in electronic properties of the polymorphs of alumina is observed. The effect of possible phase transitions on ruby (Cr⁺³-doped Al₂O₃) fluorescences is discussed.

A precise calculation of the exchange interaction constant J_RT between the rare-earth sub-lattice and the transition metal sub-lattice in R₂Fe_17-xM_x(R: rare-earth, M = Al or Ga) compounds is given. The calculated values for Tb₂Fe_17-xGa_x(x = 6 and 7) and Dy₂Fe_17-xAl_x(x = 5, 6, 7 and 8) compounds are in excellent agreement with the values derived from the high-field measurement.

The ceramic samples with nominal composition of La_2/3Ca_l/3Mn_l-xFe_xO₃ (0.01 ≤ x ≤ 0.20) were prepared by solid state reaction method. The effect of Fe doping on the Mn site was measured by the positron annihilation technique and Mössbauer spectroscopy. Upon doping, no appreciable structure change and electronic structure change in Mn-O plane were observed in the series of compounds. The Mössbauer parameters show that the iron probe has stable 3+ valance with the high spin state in all samples. Moreover, by examining the shape of the spectra, the tendency can be found that the isomer shift and quadruploe splitting increase with the increasing Fe⁺³ content. This phenomenon shows the local lattice distortion and the localization of d-electrons with the increasing Fe-doping content.

Electron paramagnetic resonance (EPR) measurement of CsNiCl₃ compound has been performed at 192 GHz in the temperature range from 300 to 5K, along the axes of main g tensor. The energy levels and the g-factors are calculated. The linear thermal expansion coefficient ( 2.77x10^-5 K^-1 ) for the Ni²⁺-CI^- bond distance is studied by combining EPR and optical absorption spectra with changing temperature.

A novel technique to extend template application of anodic porous alumina to Si has been reported. First, porous alumina template about 400nm thick was prepared on silicon substrate by anodizing thin aluminum film with high purity of 99.99% in 15 wt.% sulfuric acid under a constant voltage of 20 V and at an electrolyte temperature of 5^oC. Then, amorphous Si layer approximately 50nm in thickness was deposited onto the surface of template by using electron beam evaporation technique followed by an Xe ion beam bombardment, upon which as-coated Si layer at the pore mouth could be removed into pores smoothly. Three runs were performed by repeating above process of deposition and post bombardment. Finally, samples were annealed at 800^oC for 30min in nitrogen. Transmission electron microscopy and x-ray diffraction analysis reveal Si nanocrystals with a size of 15-20nm being formed in the pores of template.

The bilayer heterojunction devices were fabricated successfully by using a novel oxadiazole derivative: 2, 2'- (2,5-thiophenediyl) bis (5-(4-methyl) phenyl-l,3,4-oxadiazole) (T-OXD) as the electron-transporting layer (ETL) and a pyrazoline derivative:l-phenyl-3-(dimethylamino)styry1-5-(p(dimethylamino) pheny1)pyrazoline (PDP) as the light-emitting layer and the hole-transporting layer. The emission at 500nm was derived from PDP layer. In comparison with the bilayer device of tris (8-hydroxyquinoline) aluminum (Alq) as the ETL, the luminous efficiency of the PDP/T-OXD heterojunction device was enhanced by 10⁴ times.

Positron annihilation lifetime spectra measurements were performed on C₆₀-containing chitosan as a function of temperature ranging from 290 to 380K. Both the ortho-positronium annihilation lifetime т₃ and its intensity I₃ increase with increasing temperature, however, the values of I₃ in C₆₀-containing chitosan are smaller than that in pure chitosan, and the slope of т₃ with temperature is also suppressed after C₆₀ linked. The existing three models for positron annihilation in polymer have been compared to analyze the experiment result. It is realized that only the spur reaction model, combined with the free volume model, can explain it satisfactorily. The ortho-positronium lifetime and intensity were affected by the local physicochemical environment of material, i.e., free-volume structure, electron scavenging and trapping sites, etc. The linked C₆₀ that play a significant chemical inhibition and quenching role on positronium formation and annihilation is first observed. The microstructure change brought by C₆₀ group has also been discussed.

The first spectral analysis of a spike event has been performed. It was found that the peak frequency of spectrum of the spike event on Oct. 2, 1993 drifted from higher to lower frequency for the first group of spikes, but the frequency remained almost the same for the second group. Only if the mean energy of electron beam is a monotonic or random function of time and its pitch angle is a monotonically decreasing function of mean energy, then the different observed characteristics of evolution of the peak frequency with time may be interpreted by the location of resonant circle. The spike radio emissions with one and the same peak frequency probably originated from the same region of electron cyclotron maser instability.

It is shown that evolution characteristics of black hole (BH) parameters in the pure disk-accretion are determined uniquely by BH spin parameter a_*. Some unusual evolution characteristics of the parameters of BH accretion disks, such as angular velocity, temperature and event horizon radius, are investigated in both thin and thick disk-accretion. And the corresponding turning points, a_*^c. are derived. In addition, two characteristic functions describing the evolution of BH parameters are derived for thin and thick disks, respectively.

A new method is presented to determine the thickness of spiral galaxies. Based on the rigorous solution of the Poisson equation for logarithmic density disturbance in three-dimensional spiral galaxies, we have derived an accurate dispersion relation for the stellar and gaseous disk with a finite thickness. From this relation, a new method is put forward here for determining the thickness of galaxies. We apply this way to M31 and get the thickness of about 0.7kpc, which is in good agreement with the previous results.