In order to meet the requirements of wide-band hyperspectral Czerny-Turner spectrometer, based on the aberration theory, on the one hand, the astigmatism generated by the grating is used to compensate the astigmatism of the spherical mirror, and on the other hand, the opposite astigmatism is introduced through cylindrical mirror to compensate for the residual astigmatism, so as to achieve the full range elimination of astigmatism, and at last to improve the resolution of the Czerny-Turner structure spectrometer imaging system. Firstly, the basic formulas of grating and cylindrical mirror to compensate for astigmatism is deduced, and then based on this, the Czerny-Turner spectrometer imaging system with full-band astigmatism in the band of 900-1700 nm and 1700-2500 nm are designed respectively. Finally, the two parts are combined through the front optical path, thus realize the astigmatism Czerny-Turner structure spectrometer imaging system in the full range of 900-2500 nm. The full-band resolution of the spectrometer is less than 10 nm, the object-side numerical aperture is 0.07, and the full-band root mean square radius is less than 4 μm. The optimization analysis of ZEMAX shows that the designed spectrometer not only meets the astigmatism elimination requirements in the whole band, but also has good imaging quality.

Plasma emission spectroscopy is one of the important diagnostic methods to study the physics of plasma within tokamak. There are complex atomic and molecular physical processes in the boundary plasma, and some weak particle spectrum signals are mixed witha lot of noise. Therefore, whether the noise can be effectively removed and the signal quality can be improved is of great significance for subsequent analysis and understanding of related physical processes in experiments. Taking the simulated signals and the tungsten atomic spectrum data in tokamak experiment as research subjects, the denoising effect of wavelet threshold denoising method is studied in this work by using the signal-to-noise ratio(SNR) and root mean square error(RMSE) as the judgement basis of filtering effect. The comparative analysis of simulation experiments shows that when sym8 wavelet base, 4-layer wavelet decomposition, heuristic threshold calculation and progressive semi-soft threshold function are selected for wavelet denoising, the maximum signal-to-noise ratio of 19.2166 and the minimum root mean square error of 0.0290 can be obtained. Furthermore, the as-received approach and the best matching parameters are applied to the signal processing of measured divertor tungsten atomic spectrum, and a good denoising effect is also obtained. So, it is validated that the wavelet threshold denoising can effectively eliminate the noises in the tungsten atomic spectrum while avoiding signal distortion, that is, the method can significantly improve the signal quality.

The ground state structure, bond length, total energy, dipole moment, charge distribution, energy gap, infrared spectrum and potential energy surface of cesium bromide(CsBr) molecule under the action of external electric field(-0.015-0.035 a.u.) are studied by using Semi-empirical/PM6 method. The results show that the molecular structure of CsBr changes significantly under the action of an external electric field. With the increase of the external electric field in Cs-Br bond direction, the molecular bond length, electric dipole moment, electric charge population and energy gap gradually decrease, while the total energy gradually increases, and the strongest peak of the molecular infrared spectrum appears blue shift. On the other hand, with the increase of the applied negative electric field, the molecular potential energy surface decreases, and the potential barrier decreases gradually and finally disappears. It is also found that Cs-Br bond of CsBr molecules will be broken under an external electric field with an intensity of-0.015 a.u., leading to the dissociation of CsBr molecules, which provides a theoretical basis for the protection of the atmosphere.

Reflective optical system has the characteristics of no chromatism, compact structure, small size, excellent imaging performance and so on, which makes it very popular in space remote sensing detection field. Firstly, based on the aberration expressions of coaxial four-mirror reflective optical system, the evaluation objective function of imaging performance is established taking root mean square of system wave aberration as standard. Then, the developed adaptive variant probabilities genetic algorithm is applied to solve the evaluation function, and a set of suitable optical parameter solutions of initial structure of the coaxial four-mirror reflective optical system are obtained. After that, based on the above solution system structure, the proper off-axis operation is performed on it to eliminate the obscurations, four optical surfaces are set as even aspheric surfaces and the aberration of the system is optimized by using the optical design software Zemax. Finally, an off-axis four-mirror reflective optical system with good imaging performance is designed, which has a focal length of 800 mm, a working wavelength of 0.4～1.6 μm, a full field of view angle of 1° and an pupil diameter of 80 mm. The results show that the proposed research method provides an effective means for designing the kind of off-axis reflective optical systems, and has strong practical value.

The propagation properties of flat-top Gaussian beams in free space, single lens system and complex optical system are investigated by numerical method. It is found that when a flattened Gaussian beam propagates in free space, it will first present a hollow structure, then two side peaks form, at last the two side peaks will gradually merge into a single-peak construction with the propagation distance, and the Gaussian-like construction of single-peak can maintain for a long distance. While propagating ina single lens system, the flattened Gaussian beam presents strong focusing effect at the focal point, and after a certain distance, the beam will return to the flat-top distribution again. However, in the complex optical system composed of aperture and lens, the flat-top distribution of beams cannot recover after the focal point because of the restriction of the aperture, which indicates that the aperture should be avoided in the path of flat-top beam.

In order to solve the problem of image enhancement in quantum image processing, a quantum image pseudo color coding method based on gray level-color transformation method is proposed. Based on the generalized quantum image representation(GQIR) model, the hot metal code segment function is quantized, and the quantum circuit diagram of the algorithm is given. The quantum circuit design is divided into three parts: quantum R converter, quantum G converter and quantum B converter, and the number of basic quantum gates used in the total quantum circuit diagram is 2947. Compared with classical pseudo color coding, quantum image pseudo color coding is based on the superposition and coherence of quantum states, which can reduce the spatial and temporal complexity exponentially. The simulation results show that the algorithm is feasible.

In order to improve the detection and recognition effect of the two-stage target detection algorithm Faster R-CNN on small target of drones, an improved Faster R-CNN target detection algorithm is proposed. In the improved algorithm, firstly, the feature extraction network of the original Faster R-CNN algorithm is improved, and ResNet-18 with fewer convolutional layers is used as the backbone network to reduce the number of parameters of the algorithm. Secondly, according to the characteristics of the drone target, the feature fusion method in the feature pyramid networks of Faster R-CNN is improved to enhance the contrast between target feature and background feature. Thirdly, the bilinear interpolation method is used to solve the problem of the deviationof the prediction frame caused by the pooling of regions of interest. Furthermore, the verification experiments are carried out on the constructed low-altitude drone data set. The results show that the improved Faster R-CNN target detection algorithm hasa detection speed of 35.5 frames per second(FPS), which is about double the speed of the original Faster R-CNN algorithm(15.8 FPS), and the improved algorithm’s mean avergage precison(mAP) is increased by 0.7%, which effectively improves the detection and recognition performance of the algorithm for drone small targets.

In order to overcome the inaccurate tracking problem of Kalman filter in the case of long distance and occlusion, a multi-target real-time tracking framework is designed. In the framework, neural network is used to predict the state of the target object in three-dimensional space, Hungarian algorithm is used for data association frame by frame, and the trajectory management module is designed to manage the corresponding trajectory to realize multi-target tracking. Compared with the traditional framework, this framework does not need to perform Kalman filtering in the image space. It can not only track occluded targets accurately at high frame rate, but also has excellent performance for long-distance targets. The performance of the framework on Kitti dataset is as follows: multi-target tracking accuracy is 79.22, multi-target tracking accuracy is 78.33, most of the lost number is 54.19, most of the tracking number is 13.21, ID transition number is 16, the running speed is 39 frames per second. Compared with the traditional Kalman framework, the accuracy of the designed framework is improved by 11%, and the anti occlusion performance is also greatly improved.

In order to understand and deal with the basic theoretical problems of the electron spin transport in mesoscopic systems, nonequilibrium spin transport properties of typical three site one-dimensional(1D) quantum chain system with electronic interactions are analyzed and the corresponding analytic formulas are deduced. Firstly, the initial charge on each site of the chain is calculated from the exactly derived ground state under the half-filling assumption. Then, based on Keldysh formalism, the basic theoretical methods are described in detail, and the main analytic formulas of the nonequilibrium spin transport properties(differential spin conductance, spin transport current and electronic charge distribution, etc.) of the 1D chain systems are derived considering Hartree-Fock approximation and Coulomb electronic interaction. Both the cases, namely, the scattering process considering the Coulomb repulsion force between the spin-up and spin-down electrons and the scattering process considering the spin-spin interaction due to spin degree of freedom, are considered. Finally, under the conditions of typical parameters, the initial charges and calculating formulas are used to calculate the nonequilibrium spin transport properties of the chain system self-consistently, and the corresponding physical interpretations of the numerical calculation data are provided, which verifies the correctness and validity of the formulas.

The electron transport in mesoscopic system provides a theoretical basis for the design of electronic devices with nanoscale nanostructures. Based on the transmission matrix method proposed in the previous research, the transmission coefficient of the cross-shaped four terminal quantum dot matrix system is calculated, and then the four terminal quantum dot array system model is transformed into a two terminal model to study the electronic transport of the asymmetric and symmetric cross quantum dot array system relative to the intermediate origin. The results show that the number of transmission peaks of the cross quantum dot array with space reversal symmetry is equal to the number of quantum dots onthe quantum dot array, and the transmission coefficient depends on the incident electron energy, the quantum dot width and the quantum number, but not on the transition integral.

Data reconciliation protocol is one of the important steps in quantum key distribution(QKD), and its efficiency directly affects the key rate of QKD. Therefore, a continuous variable QKD data reconciliation protocol based on concatenated polar coding andmultistage decoding is proposed. Based on the multistage coded modulation system, the proposed protocol uses the concatenated Polar codes with better error correction performance as component codes in the multistage decoding. The performance of the protocol is analyzed by simulation. The simulation results show that the reconciliation efficiency of the proposed protocol is greatly improved, while the bit error rate of the key decreases greatly at the same time. When the signal-to-noise ratio is equal to 0.5 dB, the bit error rate of the protocol is less than 10-3. This protocol is of great value to the application of continuous-variable QKD.

In recent years, quantum entanglement has been widely used in quantum communication, quantum computation and so on. Therefore, it is of great significance to prepare high-performance and integrated quantum multicomponent entanglement sources. The silicon nitride microring resonator is pumped by a tunable laser in this work, and four wave mixing occurs in the resonator under the action of third-order nonlinear effect, resulting in the generation of signal light and idle light. Then based on the entanglement criterion for judging the entanglement between signal and idle light, the degree of entanglement between signal and idle light is calculated. The results show that eight pairs of two-component continuous variable quantum entangled states can be generated in the microring resonator. Besides, the entanglement source system has several advantages such as small size, low power consumption and simplified integration, which has important research value in the field of integrated optical quantum chips.

Quantum-noise randomized cipher(QNRC) is a kind of physical-layer encryption technology based on Heisenberg uncertainty principle, which can be applied to high-speed, large capacity and long-haul optical fiber communication network. In order to solve theproblem that the modulation and demodulation of M-ary Y-00 ciphertext signal in QNRC system is limited by ADC chip with high sampling rate and high conversion depth, a method to modulate and demodulate Y-00 ciphertext signal is proposed by using multiplephase modulators(PMs) in series, and the performances of the proposed scheme are verified by using VPItransmission Maker Optical Systems simulation software. The simulation results show that based on the series structure of multiple PMs, a phase shift keying- quantum noise random encryption(PSK-QNRC) system with 126 ciphertext states, 10 Gbit/s data rate over 1000 km optically amplified links is realized. And it is also shown that reducing the mesoscopic power of the ciphertext quantum state can improve the security level of QNRC system, but it will damage the transmission performance of the system at the same time. Therefore, it is very important to select the appropriate mesoscopic power to optimize the security and reliability of QNRC system.

Grover quantum search algorithm can speed up the traditional search algorithm by square order, so it has been widely concerned since it was put forward. In this paper, the Cirq framework based on Python is introduced into the traditional Grover algorithm and the circuit details of the algorithm is realized by simulation at first, and at the same time, the characteristics and defects of the algorithm are verified intuitively through experimental results. Then, in view of the shortcomings of the search success rate of the traditional Grover algorithm, a precise improved Grover algorithm based on phase angle rotation is theoretically introduced, and it is simulated by Cirq framework, which verifies the effectiveness of the algorithm with a success rate of 1. It is believed that the introduction of the Cirq framework can provide a powerful tool support for the research of quantum algorithms and the optimization of quantum circuits.

The key to the study of Deutsch problem lies in constructing Oracle circuit and synthesizing Deutsch circuit. A circuit synthesis algorithm for n-bit Deutsch-Jozsa algorithm is proposed for the first time by using the Cirq framework introduced by Google. The algorithm generates f(x) set randomly according to the number of input quantum wires n, so as to construct Deutsch circuit and simulate it. According to the algorithm, the probability that the set of f(x) generated is a constant function or anequilibrium function is equal. On this basis, the synthesis algorithm is further optimized. The optimized algorithm not only reduces the total number of gates and layers, but also simplifies the structure of the circuit. The simulation speed of the circuit is faster than that before optimization by several times. For example, when n=15, the simulation time after optimization is only 1/6 of that before optimization.

Quantum entangled state is an important resource for quantum computation and quantum communication. The conditional shift operation in quantum walk is a non-local operator, which can lead to entanglement between walker and coin. For the ordered quantum walk where evolution operation is constant with time, the entanglement depends on the evolution operation, initial state and evolution time of the system. The effects of these factors on the entanglement entropy are calculated respectively in this work. Thecalculation results show that when the appropriate evolution operation and initial state are selected, the maximal entangled state can be obtained after a few steps. By adding phase factors at different positions in space, the proposed method provides anefficient production of entanglement which can be realized in simpler setup.

A humidity sensitive one-dimensional photonic crystal structure is designed by use of two-dimensional nano materials with a periodic arrangement, and then based on the optical properties of the transfer matrix of multilayer media, the humidity sensitive optical properties and humidity sensitive band gap properties of the transmission spectrum of the designed sensing structure are studied, as well as the relationship between environmental humidity and the band structure of one-dimensional photonic crystal under the two light propagation modes of TE and TM. The results show that in TE and TM modes, the one-dimensional photonic crystal has an obvious photonic band gap in the range of 0%～100% relative humidity, and the start wavelength, termination wavelength and band gap width of the photonic band gap change regularly with the environmental humidity.

The complex variable Hermite-Gaussian beams with different orders have different intensity and phase distributions. When the order increases, the number of vortex singularities increases, i.e., the number is equal to the order, and both the beam width andellipticity also increase. The split-step Fourier method is used to numerically simulate the propagation of complex variable Hermite-Gaussian beams in strong nonlocal medium. It is found that when the initial power of the beam is not equal to the critical power, breather with oscillatory width can be obtained. When the initial power of the beam is equal to the critical power, the stable soliton can be obtained. Further study shows that the rotation direction of the soliton light intensity depends on the sign in front of the imaginary part in the parameter ξ, and the critical powers of solitons with different orders are equal, but the orbital angular momentum increases with increase of the order. Moreover, after adding noise, the propagations of complex variable Hermite-Gaussian solitons are still stable.

Considering the attenuation characteristics of the seawater channel in underwater wireless optical communication(UWOC) and the influence of system self-noise on the modulation performance, an improved Gardner timing synchronization algorithm is proposed,and an UWOC system model is established based on offset quadrature phase shift keying(OQPSK) modulation, then the influence of water types and transmission distance on the bit error rate(BER) performance in the OQPSK modulation system is simulated and analyzed. The simulation results show that compared with quadrature amplitude modulation(QAM), quadrature differential phase shift keying(QDPSK) and on off keying(OOK) modulation systems, when the BER of the system reaches 10-3, OQPSK modulation can obtain the gains of about 2.2, 4.4 and 6.2 dB respectively. And compared with OOK modulation, OQPSK modulation can obtain a distance gain of 2.3-8.2 m. In addition, in the underwater channel with large attenuation, the proposed Gardner algorithm can improve the synchronization performance of the OQPSK modulation signal, and compared with the traditional algorithm, the bit error rate of the proposed algorithm is significantly reduced, and a gain of about 12.5-14.2 dB can be obtained.