Food additives butyl hydroxy anisole (BHA) and its mixtures with polythene of different ratio are measured by using terahertz time domain spectroscopy (THz-TDS) technology, and the absorption spectrum and refractive index spectrum of 0.2～2.6 THz band are obtained. Experimental results show that there are three obvious absorption peaks of the sample in the band, which locates at 0.64, 1.14, 1.81 THz, respectively. The fingerprint spectrum can be used for the detection and identification of the substance in THz band. The terahertz spectra of BHA mixture are analyzed by the least squares method. Results show that the correlation coefficient between the terahertz absorption coefficient and mass fraction of BHA is larger than 0.98. The numerical calculation of single-molecule BHA is carried out with density functional theory. It is indicated that the terahertz absorption peaks have relationship with molecular conformation and molecular internal motion.

Influences of time delay on photoelectron spectra and state populations of nonadiabatic coupled NaI molecules in intense femtosecond pump-probe laser field are investigated by using three-state model and time-dependent wave packet method. Results show that the wave packet moves periodically on the potential energy surface with roundtrip time of 1000 fs. When time delay is 200 fs, the wave packet reaches the crossing region for the first time and splits into two parts. The wave packet returns to the crossing region and splits again at 800 fs. The periodical motion of the wave packet results in the periodical variation of photoelectron spectra peak position. The splitting situation of wave packet in the cross region affects the distribution of state populations. The wave packet motion control and selective distribution of state populations can be achieved by adjusting pump-probe delay time. The results can provide some reference for realizing the optical control of molecules and quantum control process experimentally.

Affinity propagation (AP) algorithm takes all data as potential clustering centers. Clustering is carried out by message passing based on the similarity matrix. But it is not appropriate for subspace clustering. AP subspace clustering algorithm based on attributes relation matrix (ARMAP) is an asynchronous soft subspace clustering algorithm. This algorithm calculates attribute relation matrix through α-β neighborhood of attribute a. The candidate of all interesting subspaces is achieved by looking for the maximum sub-matrixes of attribute relation matrix which contain only 1. All subspace clusters can be obtained through AP clustering on interesting subspaces. The method obtains interesting subspaces correctly and reduces time complexity at the same time. It not only keeps the advantages of AP clustering algorithm, but also overcomes the shortcomings of AP algorithm which can not be used for subspace clustering.

The key of license plate recognition system is character recognition, and the core of character recognition is to extract character features. Wavelet transform can obtain the details and structure features for characters, and the invariant moment can describe it well, which are combined to extract the character features. The character strokes feature is extracted by using the directional feature of high frequency sub-images which are decomposed by tensor product wavelet, and the alliance feature vector reflecting the structural and statistical features of characters is obtained. The decomposition of character images adopts the second generation lifting wavelet algorithm, which further reduces the computational complexity. Experiment results show that the alliance feature vector extracted by the proposed method can achieve 98% character recognition rate, which can meet the requirements of practical application.

Based on Bell polynomials, the bilinear form of variable-coefficient Gardner-KP equation is constructed. Single, double and multiple solitary wave solutions of the equation are obtained using the perturbation expansion method, and the characteristics of single solitary wave are analyzed. Based on the bilinear equation, Ba ¨cklund transformations of Bell polynomials with parameters and bilinear form of the variable-coefficient Gardner-KP equation are derived.

The exp［-φ(ξ)］-expansion method can be used to solve the nonlinear evolution equation with variable coefficients. By taking the generalized variable coefficient KdV-mKdV equation and variable coefficient (2+1)-dimensional Broer-Kaup equations as an example, the solving process is realized and singular travelling wave solutions are obtained, which are expressed in terms of the exponential functions, hyperbolic functions, trigonometric functions and rational functions. When parameters are taken to be special values, the kink type solitary wave solutions are derived. It is shown that the exp［-φ(ξ)］-expansion method is suitable for solving the nonlinear evolution equations with variable coefficients, and it is more general.

In order to reduce the frequency noise of Raman laser, a phase-frequency double-modulation frequency stabilization technique is proposed. The laser is modulated by a fiber electro-optical phase modulator (F-EOM) and large-detuned sidebands are produced. Radio-frequency(RF) signal is used for frequency modulation of the microwave driving signal of F-EOM, and one of the large-detuned sidebands is locked to a saturation absorption spectral line of rubidium atoms by lock-in amplification. The frequency stabilization and 2 GHz frequency shift of Raman seed laser are realized by using this technique, and the linewidth of Raman laser is narrowed down to 56 kHz. The single measurement noise of atom gravity interferometer induced by Raman laser frequency noise is expected to be reduced to 7×10-9 s-2.

Based on numerical simulation of Gross Pitaevskii(G-P) equation, the dynamical properties of Bose-Einstein condensed gas quantum vortex in a rotating two-dimensional optical lattice are investigated. Influences of optical lattice constant d and optical lattice depth ν0 on quantum vortex are analyzed. Results show that the formation process of quantum vortex becomes faster with increasing of ν0. The physical essence of this dynamic behavior is analyzed by calculating the evolution of system free energy with time. When ν0 is more than 50, there is pinning effect. That is to say, the quantum vortex is fixed on the extreme point of potential energy by optical lattice. When d is greater than 2.7dc (dc is the critical constant), the vortex-antivortex pairs are found.

Influence of Unruh effect on quantum entanglement of two Dirac particles in non-Markovian environment is investigated. Results show that the sudden death and revival of entanglement occur only in some special cases. When the detector is in noninertial frame, Unruh effect has a great influence on the entanglement revival phenomenon. When the acceleration of detector in noninertial system is not more than a critical point, the sudden death and revival of entanglement still occur, while they don’t occur when the acceleration is greater than the critical point. A reasonable explanation is proposed that Unruh effect affects the memory effect of non-Markovian environment, the appearance of quantum entanglement and its growth rate in the environment.

In most cases, there is only one singer. When the original signer can’t sign the document personally, in order to ensure the validity of the document, and prevent excessive concentration of the rights, the signer can entrust more than one person to sign the document and validate it. Quantum key distribution protocol is used to ensure the security, and the signature and verification are carried out by using unitary transformation. There is no requirement for the order of signature and verification, and the number of signature and verification can be different, which greatly improve the work efficiency. The correctness and security analysis show that the technical implementation of the scheme is simple, and it can resist active and passive attack. It is a safe and realizable quantum multi-proxy blind signature scheme.

Three-party, four-party quantum secret sharing schemes are proposed based on two different four-particle entangled states, in which the secret information adopted is an identical unknown two-particle entangled state. In the quantum secret sharing scheme, the sender implements appropriate Bell or GHZ state measurement on the owned particles. The sender and partner inform the receiver measurement results by classical communications. The receiver can reconstruct the initial quantum state information by implementing the corresponding quantum operation with the assistance of other collaborators. The security of the proposed two schemes are discussed and compared, and it’s found that the four-party quantum secret sharing sche me is more reliable.

Based on the perfect transfer theory of single qubit information in spin chain, the influence of two kinds of low-intensity magnetic fields independent on time acting on N=3 spin chain on single qubit quantum information perfect transfer is investigated. The Hamiltonian including magnetic field system is diagonalized, and the evolution operator effect is taken into account. Results show that a constant low-intensity magnetic field with uniform space and independent on time has no influence on fidelity of information transmission. The low-intensity magnetic field independent on time which is symmetry to the center of the spin chain and contrary in direction affects conditions for perfect transfer of quantum information. The stronger the magnetic field is, the shorter the time needed will be to realize perfect transfer.

The two-body and three-body entanglement dynamics behavior of two pairs of non-interacting, spatially separated atoms in dual-mode cavity field is investigated. The non-degenerate two photons Tavis-Cummings model is investigated. Influences of the initial state of entanglement, coupling strength between atom and cavity field, optical fiber mode and cavity field on entanglement are analyzed by numerical calculation. Results show that initial state of entanglement has significant influence on entanglement between atoms. The larger coupling strength between cavity filed and optical fiber mode can achieve the transfer of maximal entanglement between atoms. The larger coupling strength between atom and cavity field can help build up the three-body entanglement between two atoms and cavity field.

Based on the geometric quantum discord measurement method proposed by Dakic, the geometric quantum discord of double Jaynes-Cummings (J-C) model is investigated. Influences of the initial state purity, entanglement degree, coupling constant between atom and cavity, intracavity photon number on the evolution characteristics of geometric quantum discord with time are analyzed. Results show that geometric quantum discord can be increased by increasing the purity and initial entanglement value. The non-zero photon number leads to the decay of geometric quantum oscillate oscillate. The oscillation frequency can be changed by adjusting the coupling constant between the atom and cavity.

The nearest quantum circuit is required to meet the nearest neighbor constraint, and interaction occurs only between the adjacent qubits. The linear quantum circuit is an important part of quantum circuit. Linear nearest neighbor quantum circuit can be represented by Boolean matrix, and the fast determination method for the validity of Boolean matrix is investigated. The time complexity is changed from n!(n-1) to O(n2). A parallel synthesis algorithm for large scale linear nearest neighbor quantum circuit is proposed based on the valid Boolean matrix, and the circuit synthesis is completed in less than 10 s for an arbitrary linear nearest neighbor quantum circuit with 128 lines. The proposed parallel method can not only guarantee accuracy, but also greatly reduce synthesis time of quantum circuit, and scale of the solved circuit is expanded.

In order to eliminate the effect of outdated channel state information(CSI) on cross layer resource allocation efficiency in distributed wireless multi-hop network environment, and improve the accuracy of cross layer joint resource allocation, a compensation cross layer joint resource allocation algorithm based on channel correlation is proposed. The conditional probability density function between the instantaneous and outdated channel state information is adopted, and the closed solution of the conditional capacity under the condition of signal to interference plus Noise Ratio(SINR) is obtained based on Rayleigh fading channel model. In order to compensate for the partial network performance loss, a joint congestion control, channel allocation and power control algorithm considering the outdated state information is proposed. In the process the network is modeled as a Networkunility Maximization (NUM) problem, and the variable link data rate and power resource constraints are used as constraints. By using Lagrange dual decomposition technique, the NUM problem is solved by distributed solution. Experimental comparison analysis show that under the promise of ensuring lower complexity, the algorithm can effectively improve the reasonable allocation of resources in distributed multi-hop network, so that the overall utility of the network is improved, and the energy consumption is reduced.

The capacitance-voltage (C-V) characteristics of 4H-SiC p-i-n ultraviolet(UV) photodetector with temperature and bias voltage are analyzed and compared. The deep-level defects in 4H-SiC p-i-n structure are observed. Results show that the high-frequency (1 MHz) C-V characteristics almost do not change with reverse bias due to the fact that i-layer of detector is in depletion state under near zero bias. The high-frequency junction capacitances increase as the result of the number increasing of thermally ionized free carriers with the increasing of temperature. Low-frequency (100 kHz) junction capacitances of the detector have a stronger voltage and temperature dependence than that of high-frequency junction capacitance, and the reason is that the carriers trapped by the deep-level defects are ionized with increasing of reverse bias or temperature, which affects the junction capacitance.