Terahertz time-domain spectral images of polymer 3D printed samples with internal defects are obtained using terahertz time-domain spectral imaging technique. The preliminary results show that the defects in the sample and the materials have different absorption and reflection of terahertz waves. The external defects of 3D printed materials can be characterized directly by terahertz spectroscopy imaging. However, for the internal defects of the sample,the results of terahertz spectroscopy imaging need to be further optimized. Further study shows that being optimized by Gaussian noise addition, superposition fusion, least squares denoising and other algorithms, clear terahertz time-domain spectral images of internal defects can be obtained. Therefore, it is shown that the internal defects of organic polymer 3D printing materials can be characterized by terahertz time-domain spectral imaging technique combined with optimization algorithms.

A laser-induced breakdown spectroscopy (LIBS) experimental device for Xuan paper composition analysis is set up, and LIBS spectral lines of Xuan paper and ordinary calligraphy and painting paper are obtained. Combined with NIST database, the composition of metal elements in the sample is analyzed, and the element calibration of spectrum is completed. According to the spectral characteristics of the sample paper, it is found that all samples contain Ca element. However, the number of characteristic peaks of Ca element in ordinary calligraphy and painting paper is relatively small and the corresponding spectral intensity is generally low, which is easy to distinguish. For Xuan paper samples, the spectralintensity of Ca element in different bands is significantly different. According to the distribution law for Ca element in five sample papers, the spectrum is divided into three sections for analysis, and a three- dimensional differentiation map method based on the relative intensity of the three bands of the Ca element is proposed. Based on the comparison of the drop point of the spectral intensity between the tested samples and the established three-dimensional map, the identification and classification of Xuan paper can be realized quickly and accurately.

Qualitative spectrum recognition algorithm is the basis of application of passive Fourier transform infrared spectroscopy (FTIR) in monitoring and early warning of toxic and hazardous gases. Three different methods, SFS, LASSO and Elastic Net, are used to perform preliminary selection of gas component variables in the FTIR spectrum by combining with the generalized cross-validation criteria. Then, the cyclic iterative CLS method is used to perform cyclic elimination of the components with concentration less than 0 in the preliminary screened variables. Finally, the direction proportion of the variables in the measurement vector is used to further select from the selected variables to get the target gas composition. In order to verify the performance of each recognition algorithm, the simulation experiments of CH4 and SF6 field emission are carried out respectively. The experimental results show that the established recognition algorithm can identify the target components quickly and effectively, the recognition response time is second level, the recognition accuracy is as high as 99%, and it can also accurately identify the interference component H2O. It is shown that the proposed algorithm provides a method basis for the application of passive FTIR technology in emergency monitoring and warning of dangerous gas leakage.

A Fourier transform infrared (FTIR) spectroscopy system based on the sun tracking method is developed to measure the composition of atmospheric pollution gases. The system consists of a solar tracker, an optical transmission section, and a spectrometer. An orthogonal mirror system, which uses the principle of pinhole imaging to realize sun tracking, is designed for collecting sunlight, ensuring that the tracking optical path is coaxial with the measuring optical path. The theoretical calculation formula of the spot trajectory on the position sensitive detector (PSD) during tracking rotation is derived to guide the PSD algorithm. The working band of the system ranges from 600 cm－1 to 5000 cm－1, and the resolution is 0.5 cm－1. The influence of the focal length of the parabolic mirror used to converge the interference beam on the interference fringe is analyzed using the optical software Zemax. The focal length value is determined to be 52.5 mm, the maximum tilt angle of the incident light under the requirements of the system index is determined to be 0.118°, and the technical indexes of measurement accuracy of the PSD and tracking accuracy of the system are also given. Furthermore, the preliminary outdoor experiment is carried out by using the developed experimental platform, and the rationality of the system is verified.

Grating spectrometer with high spectral resolution is an important tool for detecting solar atmospheric activities. As the grating diffraction efficiency is affected by the grating incidence angle, which directly affects the energy utilization of grating spectrometer, how to accurately determine the incident angle of grating is one of the important problems in the optical design of grating spectrometer. The current methods mostly depend on the experience accumulated from engineering practice. In view of this situation, taking that multiple characteristic spectral lines can obtain higher grating diffraction efficiency as the optimization index, and taking the grating incident angle as the research object, an optimal design method for high-spectral resolution grating spectrometer is proposed, and the design of high spectral resolution solar grating spectrometer for 1 m new vacuum solar telescope (NVST) in Yunnan observatory is given.

With the development of image processing technology and the progress of embedded hardware, machine vision of unmanned aerial vehicle (UAV) has become a very hot research field. Automatic landing control of UAV is one of the key technologies of UAV flight control system, which plays an important role in the stability, accuracy, reliability and real-time performance of UAV landing. Aiming at the shortcomings of vehicle-mounted UAV with large error in automatic return and landing, through the airborne visual processing unit, the landing platform of the UAV is processed by using image processing algorithm, and the acquired location information of the UAV and landing platform are converted into real coordinate information byusing the coordinate conversion algorithm, and then the UAV is controlled to achieve precise landing by simulating the remote control lever. Experiment shows that the UAV landing platform can be accurately identified by using the proposed method. Compared with the experimental results of only GPS positioning, this method can effectively increase the accuracy of UAV landing and has certain practical application value.

The energy levels and quantum states of electron in N symmetric potential well are investigated by using classical method. Based on Schrdinger equation and the standard conditions of wave function, the (4N－2)-variables linear equations with undetermined coefficients in the wave function are derived. The transcendental equation is obtained from that the coefficient determinant equals to zero. Then the energy levels of electron are calculated bysolving the transcendental equation, and the bound state wave function is obtained by calculating the basic solution set of the linear equations. In the case of N=2～5, well width of 1 nm and well spacing of 0.5 nm, the energy levels and wave functions are calculated numerically by using Mathematica software and the mechanism of the energy level splitting into energy band is exhibited intuitively. It is shown that the physical concept of the proposed method is clear, the process is simple and easy tounderstand, and in addition, there are no artificially adjusted parameters, and the calculation accuracy is high and the speed is fast.

In the system composed of a two-level atom with a single-mode cavity, the density matrix and population of the atom in the excited state are obtained under the condition of normalization, and the quantum speedup formula of the system evolution is given. Longitudinal speedup and transverse speedup are used to describe the dynamics evolution process of the system, and influence of the coupling strength between the atom and cavity as well as the evolution time on the speedup of system evolution are analyzed numerically. Results show that the coupling between the atom and the cavity can speed up the longitudinal evolution of quantum state, and with the increase of evolution time, the transverse speedup ofquantum state increases along with periodic oscillation.

A content-based quantum recommendation algorithm based on quantum Hamming distance is proposed. In the proposed algorithm, quantum mechanical properties are utilized to sum up the attributes of historical movies watched by users parallelly, so that the favorite attributes of the users can be calculated efficiently. Then, the quantum Hamming distance between the new movies’ attributes and the favorite attributes is derived, which represents the similarity of them. Finally, one new movie with the highest similarity is obtained, which means the task of recommendation is achieved. Analysis shows that the proposed algorithm is exponentially faster in the runtime than the classical counterpart.

Using the non-perturbative non-Markovian quantum state diffusion method, the exact master equation of the Heisenberg XXZ spin chain strongly coupled to the non-Markovian fermionic bath is obtained, and then the influence of environmental non-Markovian properties and coupling strength in different directions on the quantum coherence of Heisenberg spin chain is studied by using the master equation. Results show that the environmental non-Markovian properties can greatly change the recovery and relaxation time of the spin chain quantum coherence, and in additon, the coupling strength of the spin chains in different direction also affects the quantum coherence strength.

As reference-frame-independent quantum key distribution (RFI-QKD) protocol can make quantum key distribution (QKD) system obtain the ideal key rate and transmission distance without reference system calibration, thus it has attracted much attention recently. A new RFI-QKD protocol based on wavelength division multiplexing (WDM) is proposed. In this protocal, Alice prepares multiple signals of different wavelengths and transmits them to the receiver Bob by using WDM technology. After receiving the optical pulse, Bob uses the wave decomposition multiplexer to separate the signals of different wavelengths and then measures them, and at last calculates the final security key rate by combining the decoy state. Simulation results show that the key generation rate based on WDM RFI-QKD is affected by multiplexing channel number and transmission distance, and it increases with the increase of multiplexing channel number. Therefore, introducing of WDM technology is an effective way to improve key rate.

Secure multi-party sorting is one of the most important core issues in secure multi-party computing to protect user privacy. A secure multi-party quantum sorting protocol based on the semi-honest model is proposed to solve the problem of low security and eavesdropping of traditional multi-party sorting. In this protocol, each party participates in the calculation based on the sum of quantum Fourier transform and obtains the rank on the basis that the secret values are not leaked. Through the quantum computing simulator provided by IBM, correctness of the protocol is verified experimentally and security of the protocol is analyzed theoretically. The protocol not only provides a new idea for the existing quantum sorting, but also gives consideration to fairness, validity and security.

With the development of point-to-point fiber quantum key distribution technology and its commercial application, the multiplexing of quantum signal and classical data in the same fiber to improve system efficiency and save fiber resources has become one of the research hot issues in recent years. The source of noise is verified by the experiments based on two co-channel transmission schemes, and the influence of noise on the performance of quantum key distribution system is simulated and analyzed. In addition, the noise suppression schemes are evaluated and analyzed aiming at the existing problems in experiments, which provide experimental support for the commercial development of classical-quantum signals co-channel transmission. The experimental results show that the maximum security transmission distance in the co-propagating scheme without noise suppression at separate waveband is 75 km when the launched power is 0 dBm, while it can reach 164 kmat the same waveband by using narrow-band filtering. This work provides a feasible solution for noise suppression of co-channel transmission in future quantum-classical integrated optical networks.

Entanglement monogamy is an important physical property of quantum entanglement, which means that quantum entanglement cannot be distributed freely, that is, the entanglement size of one quantum systemwith another quantum system will limit the entanglement size of this system with other quantum systems. By means of numerical analysis, the monogamy relation of squared Rényi entropy entanglement is investigated. The function relation between the squared Rényi entropy entanglement and the squared concurrence, and the monogamy relation of squared concurrence are used to prove the new monogamy relation of squared Rényi entropy entanglement. Results show that the proposed monogamy relation of squared Rényi entropy entanglement is more applicable than that of Rényi entropy entanglement in reference[4], and more rigorous than that of the squared Rényi entropy entanglement in reference[10].

The influence of nonlinear Kerr medium on non-classical correlations and quantum state transfer in an atom-cavity-fiber system with a cavity filled with nonlinear Kerr medium are investigated. Results show that Kerr medium can increase the amount of non-classical correlations and the fidelity of quantum state transfer, and slow down the decay rate of non-classical correlations and fidelity, which means that the time of non-classical correlation and quantum state transfer can be prolonged by adjusting Kerr medium. Furthermore, how Kerr medium affects the transfer of quantum information in the system is also explored by making use of the trace distance. It is found that the decay rate of trance distance can be reduced by Kerr medium, and the flow of quantum information can be suppressed as well, which indicates that the storage time of quantum information between target atoms can be increased.

A new fourth order hyperchaotic memristor system is constructed by introducing a magnetron memristor into the chaotic system. Firstly, the characteristics of the memristor system are discussed. The hyperchaotic characteristics of the new memristor system are determined by using analysis methods including Lyapunov exponent and dimension, dissipation, infinite multiple equilibrium sets and stability, and the infinite equilibrium sets are obtained. Compared with the original system, it is found that the new system is more complex and more chaotic. Secondly, the dynamic behavior of the new system is investigated, and the transient chaos caused by different parameters and the co-existence of attractors caused by different initial values are observed. This is the first analysis of this phenomenon for a system containing constant. Finally, the simulation electronic circuit of the system is designed and built. The experimental results show that the oscilloscope results are consistent with the numerical simulation results, which provides a basis for the practical application of the memristor hyperchaotic system.