Buffer gas cooling is the most effective and practical method to cool ions in ion trap. The kind and quantity of buffer gas are the key technologies in mercury ion microwave frequency standard experiments. Buffer gas made of helium, neon or argon was studied to cool trapped mercury ions (199Hg + ) in a linear ion trap by introducing a resistance term in Mathieu’s equation. It’s found that the decay time of motion of 199Hg + in argon gas is the shortest, and the frequency shift of the clock transition (40.5 GHz) is minimum when the pressure of helium is 10-5 Torr or the pressure of neon gas is 2.4×10－5 Torr. Neon is the most suitable buffer gas among helium, neon and argon, considering the decay time-constant of motion of 199Hg + in buffer gases and 199Hg + clock transition shift’s sensitivity to the change of the pressure of buffer gas.

The extracted depth of object points are assessed by two defined evaluation measurements, the depth precision and depth correctness. The evaluation results prove the enhancement of depth extraction based on integral imaging by linear interpolation method from two aspects, the whole distribution and deviation. Because of the large number of elemental lenses and limited number of sensor pixels, the conventional depth extraction technique based on integral imaging is affected by low resolution of elemental images. The elemental images are scaled to twice by linear interpolation without any hardware movement. The precision of depth extraction is increased by 20%. The correctness of depth extraction is increased by 15%. In integral imaging, the reconstruction of three-dimensional scene and extraction of depth can be completed at the same time. It is the advantage that other methods of depth extraction do not have. The quality of reconstructed image becomes better by using the extracted depth information after interpolation. Depth extraction based on integral imaging can be used in the background removal of three dimensional scenes.

CK method is a powerful direct method for nonlinear equation. By using the modified CK method, the Backlund transformation of the (2+1)－dimensional Broer-Kaup-Kupershmidt equations were obtained. A lot of new solutions were found, and some known results are generalized.

Theoretical analysis about elements that influence pulse width of Q-switched laser was carried out. On the basis of rate equation, expressions of the relations among inversion density, photon density, and cavity loss under pulse stretching conditions were established. The cavity loss’s variation curve was plotted after numerical simulation when flat-topped laser pulse was obtained. In the experiment, proper structure of resonant cavity was designed, and by taking advantage of two thyratrons as high-voltage switches, the variation of voltage on KD*P can be controlled, so the loss can be controlled to make it satisfy the pulse stretching conditions. Finally, 420 ns Q-switched laser pulse was obtained.

A model describing optomechanical dynamics via radiation-pressure coupling with a driven optical cavity was investigated by a linearized quantum Langevin equation under resolved sideband regime. Both the movable mirror and output field present the normal mode splitting with increasing of the input laser power and the results approach the experiment very well. The effective mechanical damping and resonance frequency shift are derived. The redshift sideband leads to cooling of the mechanical oscillator and the blueshift motional sideband results in amplification. Furthermore, an approximation scheme is introduced to analyze cooling of the mechanical oscillator. Since both the normal mode splitting and cooling require working in the resolved sideband regime, whether the normal mode splitting influence cooling of the mirror is considered. Meanwhile, the key factors that dominate the ground state cooling are also discussed.

A mathematical derivation was carried out about dynamics of the interaction between single photon and cavity-quantum dot system model and the mutual conversion was realized between the stationary qubit and flying qubit by numerical stimulation. The results show that the photon emitted from the cavity-quantum dot system is a smooth wave packet. By changing the parameters such as laser pulse time, the entanglement between photon and atom in quantum dot can be realized, which is the basis for realizing the entanglement between atoms in different quantum dots. These results are important to solve such hot problems as the construction of interface of quantum computers based on cavity-quantum dot system, preparation of entangled states and realization of controlled gates in the system.

Quantum game is one of the important branches in quantum information. Based on the theory of the single-coin-tossing quantum game, quantum game of the same color cards is discussed here, and the theory is also extended for the model which has N states. In classical game, two players shuffle the 13 cards which have the same color in turn, and anyone can not control what the last card is. In quantum game, if one of the players, such as Bob, shuffles the cards using quantum strategies instead of classical ones, while the other player still adopts the usual classical operation, he can always make the last card be what he wants. And then, it is concluded that quantum strategies are more successful than classical ones for the game of the same color cards.

A new quantum identity authentication scheme is proposed based on chaos. The scheme combines the extreme sensitivity to initial conditions and parameters of chaotic system and good pseudo-randomness of chaotic sequence with absolute security of quantum cryptography. It can resist the attack on initial values and parameters of chaotic system which is based on finite precision. In order to solve the chaotic iterative asynchronous problem, principle of quantum teleportation was used in the program implementation process. The scheme realizes the “one-time pad” authentication. The whole authentication process is simple in implementation with mobility and provable security.

The quantum correlation of a two-qubit Heisenberg XXZ model was investigated through applying two independent and controllable magnetic fields (B+b) and (B－b) on the two qubits respectively and changing the coupling parameter Jz, magnetic field B, inhomogeneous magnetic field b and temperature kT. The behavior of quantum correlation and that of thermal entanglement under one and the same parameter is compared. The results show that quantum correlation can exist for a wider parameter range than thermal entanglement. In addition, for a certain region of parameter, quantum correlation and thermal entanglement exhibit completely different behaviors.

A scheme is presented for generating four-photon Greenberger-Horne-Zeilinger (GHZ) states with resonant interaction between a cascade type three-level atom and two bimodal cavities. In the proposed protocol, the quantum information is encoded on Fock states of the cavity fields. Schr?dinger equation of the system is solved and quantum states of interaction system are obtained. The detection of atom can collapse cavity to the desired GHZ state. It is shown that the scheme is simple and the experimental implementation is feasible.

A robust scheme was proposed for generating maximally W entangled states of cavity field in atom-cavity-fiber system. The scheme requires that the coupling coefficient between cavity and atom is much smaller than Rabi frequency. The atomic spontaneous emission and fiber modes decay are suppressed efficiently via employing adiabatic evolution along dark states. So it is insensitive to the small fluctuation of some parameters. It is also convenient only by adjusting atom-field couplings appropriately to generate W state deterministically. This system can be considered as an ingredient of the quantum network.

Spatial optical solitons were studied in Kerr medium with transverse nonperiodic modulation by numerical method. The results of numerical simulation show that there are three kinds of spatial optical solitons. They are petronas soliton, basic soliton under the conditions of lower and higher power of light respectively, and bipolar soliton characterized by stable transmission. The stability analysis of the three kinds of spatial optical solitons based on the linear stability is carried out to obtain the stable spectrum in stable transmission, from which the transmission conditions are generalized for stable transmission of the three kinds of spatial optical solitons.

Laser induced plasmas spectroscopy (LIPS) has acquired great interest in recent years as a new method of elemental analysis. Qualitative information about the elemental composition of an object can be rapidly obtained using LIPS. In the experiment, laser induced plasma spectroscopy was used to determine the carbon content in carbon steel. The plasma was formed by focusing a Nd:YAG laser on the sample surface. By optical emission spectroscopy of the plasma, 193.09 nm C line was selected for analysis. The calibration curve was obtained, and the detection limit was within 460 ppm. The results show that this technique can be applied for direct composition determination in steel analysis.

Different kinds of optical lattice structures fabricated by holographic interference with top-cut prisms were simulated, which provided some references for making photonic crystal by prism method. Using holographic interference theory, optical lattices prepared by interference of several light beams with top-cut hexagonal prisms were analyzed, and the influence of light beams number, polarization direction and phase to lattice structures were taken into account. Changing the number of light beams can fabricate normal and skew hexagonal optical lattice with different periods. Changing light beams’ polarization characteristics can influence the shape of lattice points of optical lattice. Changing the initial phases of light beams can fabricate honeycomb structure. And tenfold rotationally symmetric optical quasi-lattice structures fabricated with top-cut pentagonal prism were simulated. Also the band-gap diagrams of hexagonal and honeycomb polymer photonic crystal were calculated by plane wave expansion method, which demonstrated that honeycomb photonic crystal can form large photonic band-gap more easily.

In temperature measurement with near-infrared colorimetry method, when the environment radiation intensity in furnace is higher than that of work piece being detected, accuracy of measurement is influenced by environment radiation significantly. In order to obtain more reliable results, according to measurement analysis, the relationship was obtained between projected absorption rate of radiation, reflectivity and transmittance of the work piece detected in different temperature fields, which supplies theory basis for measuring the real temperature of work piece accurately. Furthermore, a novel resolution to eliminate background radiation in high temperature is proposed based on the results.

The electronic structure and optical properties of Sb doped ZnO, together with the corresponding results of pure ZnO for comparison, were systematically studied from the first principles based on density functional theory. The calculated results show that for ZnO doped with Sb, the lattice constant, bond length, primitive cell volume and total energy are all larger than those of pure ZnO. For the doping case, the Fermi level becomes larger than the conduction band minimum (CBM), the system grows metallic and the band gap becomes wider. For the optical properties, a new absorption peak appears near the main peak, which is mainly attributed to the transition of orbital electrons of Zn-4s and Sb-5p. Finally, it is also pointed out that for the dielectric function, the peak values of imaginary part and the static dielectric constant ε(0) value of real part become larger.

On the hypothesis that polar rod-like molecule is orientation distribution, dielectric constant of granular film on material surface was calculated by using orientation order parameters and considering the effect of local field on polar molecules with permanent dipole moment and interaction energy between molecules and material surface. The results show that dielectric constant of granular film depends on relative dielectric constant of substrate material and distance between molecules. It is aslo found that interaction energy between molecules and material surface is the only influencing factor if molecule area is close to critical area. However, interaction of local fields becomes a major influencing factor if there is great difference between molecular area and critical area.

Coherent optical orthogonal-frequency-division-multiplexing (CO-OFDM) has drawn more attention in optical transmissions as an attractive modulation format for the forthcoming 100 Gb/s Ethernet. However, CO-OFDM system requires high-speed digital-to-analog converters (DAC) and analog-to-digital converters (ADC), which may not be available today. To resolve ADC/DAC bandwidth bottleneck, with the help of orthogonal-band-multiplexing (OBM) and polarization division multiplexing (PDM), 100 Gb/s CO-OFDM system based on OBM is presented. With this scheme, simulation is done to validate the feasibility of the system model and algorithm. The result shows that the performance of MIMO CO-OFDM system based on OBM is maintained above 13 dB at 0 GHz channel spacing for 800 km standard single mode fiber (SSMF) transmission without any inline dispersion compensation and polarization controller (PC) and the DAC/ADC do not need to operate at extremely high sampling rate.

A method is proposed to directly inscribe long period fiber gratings(LPFGs) in coated standard communication optical fibers by an 800 nm infrared femtosecond laser. Influence of fiber coatings on the effective indices for fundamental core mode and cladding mode was analyzed theoretically, as well as the LPFG’s temperature sensitivity. Temperature performance of the low-order cladding mode of uncoated and coated LPFGs was tested, respectively. The results show that the presence of coating is not only the desirable protective layer for LPFGs, and most importantly, the LPFG’s temperature sensitivity is increased to 0.1173 nm/°C, in accordance with the theory analysis. The coated LPFGs, if as temperature sensors, will have a good mechanical strength and temperature sensitivity.

By the far field excitation and measurement, propagation loss of wire’s surface plasmon is experimentally investigated with structure of branched-routing silver nanowire. The experimental results show that the propagation loss depends on the exciting wavelength. The coefficient of propagation loss is measured as 0.115 μm-1 at 632.8 nm and 0.0923 μm-1 at 780 nm. The propagation loss is smaller at longer wavelength, that is, SPP can propagate further at long-wavelength laser exciting. The measurement contributes to optimizing plasmonic devices based on silver nanowire waveguides.