Efficient qubit extension is a fundamental problem that needs to be solved to obtain quantum speedup advantage for quantum computing. Due to its high feasibility and flexibility, distributed quantum computing (DQC) has become one of the key techniques for solving the qubit extension problem. According to different inter-chip communication modes, DQC can be divided into two types, teleportation-based and circuit-cutting-based DQC. The former mainly plays for the fault-tolerant quantum computing, while the latter is considered to effectively enhance the computing power of quantum computers in the noisy intermediate scale quantum (NISQ) era. In the long run, as one of the main applications of quantum network, DQC can efficiently harness the huge number of quantum computers connected to quantum networks to solve non-trivial problems. First, the origin and types of DQC are introduced. Then, the fundamentals and development of the two types of DQC, as well as widely studied application algorithms and compiling optimization methods, are provided.

To address the shortcomings of the existing oscilloscope in laboratory, such as poor integration and weak scalability, and to improve the efficiency and accuracy of mass spectrum signal acquisition, a LabVIEW-based signal acquisition and processing system for mass spectrometry and infrared spectrum is designed. Based on the LabVIEW software platform and CSE22G8 data acquisition card, the designed system can realize real-time acquisition and processing of weak mass spectrometry signals under the background with low signal-to-noise ratio using the superimposed average denoising algorithm. In addition, the synchronous control of tunable optical parametric oscillator (OPO) is realized through TCP communication protocol, so that the user can obtain the corresponding infrared absorption spectrum while collecting mass spectrum signals. Tests show that the resolution of the system is doubled compared with the original oscilloscope in laboratory, the number of sampling points can reach 2000 per microsecond, and the waveform reconstruction ability is significantly improved, indicating that the system has better data acquisition performance.

At present, more and more attention has been paid to the detection of common explosives trinitrotoluene (TNT). In this study, a low-cost fluorene-based green-emitting conjugated polymer (FGEP) is used to develop a fluorescence quenching sensor for the detection of TNT. The quenching efficiency of TNT by different thickness FGEP films at different solution concentrations is studied experimentally. The experimental results show that the quenching efficiency of the sample film with a concentration of 0.5 mg/mL (thickness of 19.50 nm) in TNT vapor reaches the maximum of 71.71%. Based on the study of the sample film with the highest quenching efficiency, it is found that the film has good reversibility to TNT, and when the excitation light intensity is 16.5 mW, the fluorescence quenching efficiency is the best. Finally, the experimental study of the samples under the action of TNT and photobleaching is carried out. The research results provide a basis for the subsequent realization of a low-cost, easy-to-prepare, highly repeatable and engineering-friendly explosive sensor.

Aiming to the problem faced by the R matrix spectral decomposition method, a spectral decomposition method based on the camera response characteristics is proposed, a particle swarm optimization BP neural network model (PSOBP) is established for the inversion of the decomposed metameric black to realize the optimization of network training weights, and simulation experiments are conducted using the global training samples and local training samples quadratic spectral reconstruction method. The results show that under the D65 light source, using the PSOBP combined reconstruction method, the mean square error of the two test sets reconstructed by the RGB camera is reduced by at least 1.71% and 0.51%, respectively, compared with the other traditional method, and the maximum color difference is 3.5579 and 2.3776, basically meeting the requirements of the human eye color discrimination threshold. While the mean square error of spectral reconstruction accuracy of WorldView3 is less than 2% in bands of 410-510, 555-565, 590-685 and 705-740 nm, the proportion of acceptable samples represented by the fitness coefficient is 91.667%, and the maximum color difference is 1.6002 and 1.1177, respectively. In addition, the spectral reconstruction accuracy and chromaticity accuracy of the proposed method have been improved compared with other methods, and the 6-channel multi-spectral camera can meet the requirements of high precision spectral reconstruction.

The high-order convex aspherical mirror is a crucial element in the optical system, and usually used as a secondary mirror to compensate for the off-axis aberration of optical systems, however, its inspection method has always been a major challenge. The back-to-zero detection method is adopted, and a combination of three lenses and a single refractive surface is proposed to compensate for the normal aberration of the high-order aspheric surface. Firstly, the quadratic comparison surface of the high-order aspheric surface is selected to simplify the calculation. Based on the third-order aberration theory, the initial structure of the system is solved, and the normal aberration of the high-order aspheric surface is compensated. After simulation and optimization using ZEMAX software, it is shown that the design results fully meet the requirements. And then, combined with a high-order convex aspheric reflector with an effective clear aperture of 170 mm and a vertex curvature radius of 266.8 mm, the root mean square of the mirror's surface shape accuracy is measured to be 0.019 λ (λ= 632.8 nm), which meets the actual detection requirements and verifies the feasibility of the proposed design method. This method provides a new idea for the inspection of large-diameter high-order convex aspheric surfaces.

Catadioptric imaging systems with large acceptance aperture are widely used in robot navigation and safety monitoring fields and so on. The sixth-order wave aberration theory of ultrawide-angle optical system applied to the aberration calculation method for aspherical optical system is analyzed firstly. Then, based on the sixth-order wave aberration theory, the aberration optimization evaluation objective function for aspherical catadioptric imaging system with large acceptance aperture is established, an optimization algorithm for solving the function consisting of multiple optical parameters is given, and the optimized structure parameters of the optical system are obtained. Finally, an optical system with wavelength ranging from 400 nm to 700 nm, maximum field of view angle of 120°, F number of 2.6 and good imaging performance is designed using the proposed method.Resultsof the design case show that the proposed method is effective, which can provide an effective means for aberration optimization of catadioptric imaging systems with large acceptance aperture.

Compared with conventional spontaneous Raman scattering, stimulated Raman scattering (SRS) often uses two light fields (pump light and Stokes light), which provides an additional degree of freedom for polarization manipulation of SRS processes. A comparative study of SRS with circularly polarized and linearly polarized pump light field is carried out in this work. Firstly, based on the nonlinear coupled wave equation, the expressions of SRS signal intensity are derived theoretically under the cases that the pump light is circularly polarized and linearly polarized while Stokes light always keeps linearly polarized. And then, taking methane molecule with spherically symmetry as an example, the SRS spectra of υ1 and υ3 vibrational modes of methane molecule in the C-H stretching region (2800-3100 cm-1) are experimentally measured under different polarizations. The experimental results are consistent with the theoretical analysis, demonstrating that the SRS signal intensity is not only closely related to the polarization state of pump light, but also to the symmetry property of molecular vibrational modes. The research provides useful insights for the polarization application of SRS.

In order to meet the long-term frequency stability sharing requirement of 10 MHz hydrogen clock signal (HCS) between different buildings in the same scientific research park, a low-cost and highly integrated solution for optical-fiber-based 10 MHz HCS transferring setup is proposed. In the scheme, a 1 GHz radio-frequency signal (1GRFS) is used to modulate the laser intensity and optical fibers are used for signal transmission.In principle, the sum of the source 1GRFS and signal reflected from remote is frequency-divided firstly and then phase-compared with the HCS to be transferred. Then the error signal from the phase comparator is fed back to modulate the frequency of the 1 GHz oscillator to lock the phase between the remote 1GRFS and the HCS. Therefore, the remote 1GRFS has the same frequency stability as the HCS. Afterwards, a 10 MHz signal is generated at the remote site through a frequency divider as RF reference output. Furthermore, experiments are carried out to verify the precision of the system. It is shown that the additional frequency stability of the HCS transferring system is 2.4×10-13 at 1 s average time and 5.7×10-17 at 10000 s average time with a fiber link of 200 m, 4.8×10-13 at 1 s average time and 2.1×10-16 at 10000 s average time with a fiber link of 20 km. The verification results prove that the long-term stability of the transferring system is better than the frequency stability of the HCS, indicating that the system can be used for sharing HCS within kilometer range.

The evolution properties of quantum information fidelity in a system of atomic Bose-Einstein condensate interacting with Pólya field state have been studied using quantum information theory and numerical calculation methods. The influences of the coupling intensity among the atoms of Bose-Einstein condensates, and the probability and distribution parameters of Pólya light field on the fidelity of quantum state are mainly focused. The results indicate that the fidelity of quantum information during the transmission depends on the coupling intensity among the atoms, as well as the optical field parameters. Among the three physical parameters, the probability parameter of the light field η have a crucial effect on the fidelity of quantum state. When η=0.01, the fidelity of quantum information is very close to that in ideal transmission process for information. On the other hand, the oscillating frequency of the system fidelity would have the larger values with the increasing of coupling intensity among the atoms of Bose-Einstein condensate, but the range of system fidelity values remains unchanged.

Thermal noise presents a major obstacle for quantum computing to scale up, and its existence puts stricter requirements on the robustness and fidelity of quantum control process. This work adopts the stochastic dynamic structure decomposition method and applies the Kubo-Einstein fluctuation dissipation theorem to the optimization of quantum dynamics, that is, how to improve the fidelity of quantum control process under thermal noise environment. Based on the characteristic that the classical path on a two-dimensional sphere can completely describe the motion of a single qubit, the research proposes a variational optimization scheme of gradient descent algorithm to reduce the thermal effect, and demonstrates its applicability via numerical simulation. It is found that the main factor affecting the fidelity of quantum control process under classical limit is thermal fluctuation. The method is expected to be mutually validated with experiments, and thus can further guide and evaluate experimental schemes towards achieving high fidelity of quantum gates.

A quantum K-means algorithm without quantum random access memory (QRAM) is proposed by combining K-means algorithm and angle encoding technology. This algorithm makes use of parallel quantum operations and can complete data loading with only logarithmic time complexity. And by pre-processing the input data, the parameter threshold of the data components is determined, so the problem of different characteristic scales of samples can be solved according to the algorithm. The main body of the algorithm consists of four main steps: coding data, similarity measurement, quantum minimum search and centroid iterative update. The operators and circuit construction involved in these steps are described in detail. Numerical experiments based on the proposed circuit show that the results of the proposed algorithm are consistent with the classical prediction results, verifying the reliability of the quantum K-means algorithm combined with parameters. In addition, theoretical analysis shows that the proposed algorithm has square acceleration in running time compared with the classical algorithms.

To address the issues of insufficient privacy protection of quotations and collusion between malicious bidders and third parties in existing quantum sealed auction protocols, a quantum sealed-bid auction protocol based on semi-quantum secure direct communication is proposed. Firstly, the protocol adopts semi-quantum secure direct communication, in which the auctioneer only needs to measure and reflect particles during communication. Secondly, the bidder can achieve the privacy protection of quotations through order-preserving transformation. Thirdly, the auctioneer can achieve privacy comparison of the transformed bid information without the participation of a trusted third party. Theoretical analysis shows that the proposed protocol is highly secured even facing attacks such as intercept-resend attack, control-NOT (CNOT) attack, phase inversion, and collusion attack. In addition, compared with the existing similar quantum auction schemes,the communication efficiency of the new protocol is not affected by the number of bidders.

Semi-quantum identity authentication plays a crucial role in ensuring communication security. By introducing a quantum third party to centrally manage keys, a new semi-quantum two-party authentication protocol based on Greenberger-Home-Zeilinger (GHZ) state is proposed. Firstly, the quantum capabilities of the participants are limited, both authenticators have only semi-quantum capabilities, and the protocol uses fewer quantum resources. Secondly, the two semi-quantum participants in the protocol only need to perform simple measurement operations and XOR operations. Through further security analysis, it is found that attacks such as impersonation attack, intercept-resend attack and entangle-measure attack cannot cause the leakage of legitimate identity information when using this protocol for quantum communication, indicating that the protocol can effectively prevent an illegal and dishonest participant from obtaining a legitimate identity, and has better security and practicality.

Understanding and reducing the influence of noise on the fidelity of transmitted particles is one of the important research directions in quantum teleportation. Different from the previously reported independent noise and the memory Pauli noise, the effect of memory amplitude damping noise on fidelity is investigated, and a method to resist this influence is proposed. According to this method, the fidelity can be improved by implementing the extra weak measurement and recover measurement before and after distributing particles respectively. The results show that, the memory factor strength of the memory amplitude damped channel is positively correlated with the fidelity. Moreover, the weak measurement and recovery measurement methods can also improve the fidelity of the transmitted particles to a certain extent in partial or full memory channels.

Optimizing quantum lines is essential to improve the computational efficiency and reduce the resource cost of quantum algorithms, especially in the case of Oracle circuit constructed from Boolean functions. This optimization process is divided into two key stages. In the first stage, the MCT gates of the same controlled points of Oracle circuits are reordered based on the minimum weight matching algorithm to minimize the number of gates for generating circuits. In the second stage, the method of template matching is utilized to further reduce the number of gates and the cost of the circuits. The experimental results show that, compared with the optimization tool of RCViewer+, for 4-10 qubits, the number of Oracle circuit gates can be reduced by about 48.3%, and the cost can be reduced by about 64.5% using Deutsch-Jozsa algorithm, while the number of Oracle circuit gates is reduced by about 25.0%, and the cost is reduced by about 18.2% using Grover algorithm.

In actual quantum computing, qubits and quantum operations exhibit different quality characteristics, which affect the fidelity of quantum computing results. While among the quality characteristics, the error rate of controlled-NOT (CNOT) quantum gate occupies a major position. This research proposes a quantum circuit conversion method that not only satisfies the connectivity constraints but also improves fidelity. The method first finds out the qubit moving path through Floyd algorithm, and constructs a heuristic function based on the success rate of one or more two-qubit gates on the path, then select the high-fidelity switching mode in this circuit. Multiple benchmark experiments show that compared with SabreSwap and StochasticSwap algorithms in IBM Qiskit toolkit, the proposed method improves the quantum line fidelity by 39.29% and 36.06% respectively.

A simple four-dimensional memristive chaotic system with multistability and amplitude modulation characteristics is constructed based on three-dimensional Sprott-R chaotic system. Firstly, the system's stability characteristics are analyzed, and it is found that the system has infinite unstable equilibrium points. And then, the complex dynamical behaviors of the memristive chaotic system are studied using Lyapunov exponential spectrum, bifurcation diagram and the projection of chaotic attractors on the phase plane. The results show that when the system parameters change, the system will change from chaotic state to periodic state through inverse periodic bifurcation. And under different initial conditions, the system can generate three kinds of coexistence attractors, namely chaotic attractors coexistence, periodic limit cycle and chaotic attractor coexistence, and periodic limit cycles coexistence. In addtion, when the initial conditions change, the amplitude of the four-dimensional chaotic signals will change. Finally, the circuit design and realization of the system are carried out to further verify the existence of the new system.