Quantum computing is a new type of computing mode that follows the laws of quantum mechanics to process information, its application covers multiple fields such as cryptography, combinatorial optimization, and quantum simulation. The power of quantum computing relies on quantum algorithms, while the quantum algorithms must first be compiled into quantum circuits to execute. Reversible circuit is an important type of quantum circuits, and the synthesis and optimization of reversible circuits is one of the main research topics in quantum compilation. Some important progress in the synthesis and optimization of reversible circuits are summarized. Firstly, the synthesis and optimization of linear reversible circuits is introduced, and the optimization results in terms of the number of controlled-NOT (CNOT) gates and the depth of circuits are discussed. Then, the size and depth optimization of general reversible circuits are introduced, the upper and lower bounds that the current algorithms can achieve are analyzed. Finally, the extensions of reversible circuit synthesis and optimization are discussed.

Due to the uneven intensity distribution of Gaussian pulsed laser beam, traditional laser-induced breakdown spectroscopy (LIBS) system has poor spectral signal stability, and the detection sensitivity for trace elements is low. To improve the analytical performance of LIBS, a combination of spherical lens and cylindrical lens is used to focus the laser beam to ablate the alloy steel sample to generate plasma in this study. The research results show that a more uniform ablation crater morphology is formed by adding a cylindrical focusing lens to the experimental system, which to some extent avoids the adverse influence of the "pointed conical" ablation crater formed by Gaussian beam excitation on the spectral signal in traditional systems, and a more stable plasma radiation spectrum is obtained. Compared with the traditional LIBS, the signal stability of characteristic spectral line intensity and background intensity in this work has increased by 24.7%-36.67% and 43.75%-57.7% respectively, and the stability of plasma temperature and electron density has increased by ~10%. Furthermore, three trace elements, Mn, Cr and Ni, in alloy steel are quantitatively analyzed using the internal standard method. The result shows that the use of cylindrical lens focusing improves the detection sensitivity of elements, and the limit of detection (LOD) of elements is reduced by 1.15-3.01 times.

The detection of metallic zinc (Zn) is of great significance in many fields. In this study, the laser-induced breakdown spectroscopy technique is used to detect Zn, and 31 characteristic spectral lines of Zn in the region of 200-895 nm are identified. Moreover, several detections are carried out under different laser energy, and it is found that laser energy has a great influence on the relative intensity of Zn spectral lines. At the same time, the plasma temperature under different laser energy is calculated, and the results indicate that the plasma temperature increases gradually with the increase of laser energy. In addition, the relationship between the ratio of ion line intensity to atomic line intensity and plasma temperature is investigated, and the results show that there is a positive correlation between the ratio of ion line intensity to atomic line intensity and plasma temperature of Zn.

A lens set that can achieve large-area uniform light spot based on LED extended light source is designed by means of freeform surface method in combination with Snell's law and energy conservation. The lens set consists of a primary lens and a secondary lens. The primary lens regulates energy to achieve uniformity adjustment, while the secondary lens shrinks the LED luminous angle to reduce the lens set structure. The Monte Carlo ray-tracing simulation shows that a single lens set can achieve a square uniform spot on the receiving surface, with an effective light flux ratio of 95.5% and a uniformity illumination of 95.7%, indicating that the lens set equipped with LED source has excellent effective light flux ratio and illumination uniformity. While for lens array, simulation shows that it can also achieve a square uniform spot on the receiving surface, with an effective light flux ratio and uniformity greater than 95%, indicating that the lens set can be extended to the lens array adapted to planner multi-LED extended source. The results show that the designed lens set and lens array have promising potential applications in satisfying high-power light sources of the fluorescence-based inverse measurement devices.

In order to expand the detection field of view angle range of solar-blind ultraviolet optical system used in the fields of high voltage corona discharge detection, tactical missile alarm system and so on, firstly, based on the anti-remote structure form, two negative crescent lenses are added in front of the paraxial optical lens, so that the full field of view of solar-blind ultraviolet optical system is achieved up to 100°; then a method is proposed to determine the first-order optical parameters of three lenses of conventional optical lens using Gaussian optics and third-order aberration theory, and lastly a transmission solar-blind ultraviolet optical system with ultra-wide angle is designed based on optical design software. The operating band of the optical system is 240-280 nm, F number is 4, and focal length is 1.0 mm. The five lenses of the system are all made of fused quartz optical material and all with no aspherical surfaces, which greatly reduces the complexity and processing manufacture cost. In addition, the value of modulation transfer function in the full field of view of the system is higher than 0.42 at the Nyquist frequency of 20 lp/mm, the relative illumination is more than 97.9% and the energy loss is very small. Therefore, the imaging quality of the system is very good and has a good practical application prospect. The research provides an effective reference for the parameters setting of initial structure and the design of this kind of optical systems.

The development of new photonic devices based on optical non-reciprocity is crucial for information processing. As information tends to be weakened during transmission, achieving amplified optical signals is a major focus of scientific research in this field. This paper proposes a simple regime to achieve amplified non-reciprocal reflection. Firstly, a strong coupling field and a microwave field are used to control a weak probe field to form a three-level coherent atomic system, enabling the detection light signal to be amplified at the transparent window. Then, the symmetry of probe susceptibility is broken utilizing the linear variation of coupling field, leading to the realization of non-reciprocal light reflection amplification. Finally, the amplification range of non-reciprocal reflection bands is modulated by adjusting the relative phase between laser fields. The numerical results demonstrate that in the nonreciprocal frequency domain, when the relative phase is Φ=0, π, and 3π/2, only one reflection band is amplified. However, when the relative phase reaches Φ=π/2, two non-reciprocal reflection bands are amplified simultaneously with a magnification range of 1.25-1.75 times. It is shown that the proposed regime can achieve dynamic manipulation of non-reciprocal reflection.

With the rapid development of quantum computing technology, it has entered the noisy intermediate scale quantum (NISQ) era. However, due to the limitations of current technology, a qubit can only be directly interacted with adjacent qubits. In order to implement the logical quantum circuit directly on the NISQ device, it is necessary to insert SWAP gates or use bridge gates to make the qubit nearest neighbor. In order to reduce the number of additional quantum gates inserted in quantum circuit mapping, this paper investigates the dynamic look-ahead based circuit mapping method, considering the impact of inserting SWAP gates in the expansion layer and the cost function model is optimized. Then the best look-ahead depth is determined when inserting SWAP gates through the simulated annealing algorithm, in order to reduce the number of inserted SWAP gates and thereby reduce the number of CNOT gates. The experimental results show that, compared with the existing mapping method, the proposed algorithm can effectively reduce the number of CNOT gates inserted in circuit mapping, and the average optimization rate reaches to 45.59%.

The spectrum, photon count rate and time correlation of spontaneous parametric down-conversion are of great significance for the broadband photodetector calibration. In the work, the spectrum and photon count rate distribution of 488 nm continuous laser pumped barium metaborate (BBO) crystal are simulated theoretically, and an experimental measurement system of spectrum, photon count rate, and time correlation are set up. Based on the theoretical results, BBO crystal phase-matching angle is selected as 24.3184°, which can achieve 605-2523 nm continuous broadband correlated photon spectral preparation, and the maximum of photon count rate can reach to 4.2716 × 107 s-1. CMOS camera and photomultiplier tube are used to measure the correlated photon ring and photon count rate, and the corresponding photodetector is selected according to the wavelength and detector response band to measure the time correlation. As a result, the correlated photon spectrum of 605-1000 nm is measured, and it is found that the measured photon count rate deviates from the theoretical value by an order of magnitude. Besides, the coincidence peaks are also observed in the range of 710 nm to 1560 nm. The experimental results verify the correctness of the theoretical model and the wide spectral characteristics and time correlation of spontaneous parametric down-conversion process, which provides a research foundation for the realization of the wide spectral correlation photon calibration in the visible-near-infrared band.

For space gravitational wave detection, as the lengths of laser interferometer arms are not matched, the laser frequency noise cannot be eliminated in common mode, leading to the weak interfering signals being submerged in large residual laser frequency noise. By time-shifting and linearly combining independent interfering signals, laser frequency noise can be greatly eliminated as laser interferometry with virtual equal interferometer arm lengths. Such a technique is called time delay interferometry (TDI). In order to experimentally validate that TDI technique can reduce the influence of laser frequency noise on gravitational wave detection to 3 × 10-7 Hz/Hz at Fourier frequency of 1 mHz on the ground, it is necessary to analyze the main frequency noise sources of laser interferometer. Based on experimental measurement and calculation analysis, experimental parameters of the laser interferometer are derived to meet the noise requirement of gravitational wave detection, including the maximum length difference between interferometer arms, laser frequency stability, air pressure stability, laser power stability and temperature stability of experimental setups.

Hyperspectral lidar (HSL) can obtain spatial and spectral information simultaneously, which provides more possibilities for three-dimention (3D) reconstruction of wood-leaf. The multi-view tree point clouds were collected using a self-developed HSL system for wood-leaf separation and 3D reconstruction. In order to meet the strict condition of traditional iterative closest point (ICP) algorithm, an improved point cloud registration method was proposed in this work. Firstly, the local feature of every point was described using fast point feature histogram (FPFH). Then, rough and accurate registration of point clouds were successively conducted based on random sample consensus (RANSAC) algorithm and ICP algorithm respectively. Finally, the wood and leaf components were separated based on the spectral data of the registered point clouds, the feature bands were extracted for wood and leaf separation on the basis of the spectral feature channel selection with random forest (RF) algorithm and support vector machine (SVM) algorithm, and 3D reconstruction of wood-leaf components was completed based on separation under different view. The experiment results show that the proposed improved point cloud registration method can achieve excellent registration accuracy both under 15° and 30° view angle difference, and the corresponding separation accuracy using RF algorithm based on feature channel selection reaches 98.17% and 98.87%, respectively.

Deep-level defects are the main cause of persistent photoconductivity (PPC) effect in wurtzite gallium arsenide nanowires (WZ GaAs NWs). The photoconductivity attenuation curve of WZ GaAs NWs are analyzed using the Gauss distribution based defect composite dynamics equation, and an average carrier capture barrier of 60.2 meV is obtained. By analyzing the transient behavior of photoconductivity under illumination, a defect photoionization model is proposed to extract the characteristics of specific defect energy levels. Through fitting the photoionization spectrum of WZ GaAs NWs, a photoionization energy of 0.69 eV is obtained. The large energy difference between the photoionization energy and the thermal capture energy implies that there is a strong coupling between the defect and the lattice for WZ GaAs NWs, which is similar to the behavior of EL2 center in zinc-blende GaAs.

In coherent optical communication transmission systems based on higher-order modulation, the signal at the receiver side is subject to phase noise interference, which has a direct impact on the system performance. The conventional blind phase search (BPS) algorithm has high line tolerance and is suitable for a variety of modulation formats. However, as the modulation order increases, the number of test phase used for BPS will sharply increase. A new low-complexity carrier phase estimation (CPE) algorithm is proposed in this work for M-ary quadrature amplitude modulation (M-QAM) format. Firstly, the relationship between the B test phase and the average Euclidean distance is obtained using the BPS algorithm. Then, a carrier phase estimation based on a two-stage BPS with cubic spline interpolation (CSI) is proposed, and the smooth curve relationship between the (2B-1) equally spaced interpolated phase and the average Euclidean distance is obtained. Finally, the phase value corresponding to the minimum of the curve is taken as the optimal phase estimation value. The simulation results show that with a small number of test phases, the carrier phase can be effectively recovered by the CSI algorithm, and compared with that of the BPS algorithm, the computational complexity of multiplier and additive of the CSI algorithm is reduced by 38% and 42% (16-QAM) respectively, which provides a new idea for carrier phase recovery.

In order to study the non-uniform strain sensing characteristics of fiber Bragg grating (FBG), a circular through hole is opened on the surface of a rectangular cantilever beam with equal section using laser cutting technology, and the displacement is applied to construct non-uniform strain distribution. The surface strain distribution of cantilever beam is simulated and analyzed. Uniform FBG (UFBG) and apodized FBG (AFBG) are pasted on the non-uniform strain distribution area of the cantilever beam surface respectively, and experimental research on the non-uniform strain sensing characteristics of FBG is carried out. The experimental results show that with the increase of displacement, the central wavelength and bandwidth of the two FBGs increase, the peak power and side mode rejection ratio decrease. However, only the center wavelength shows good linearity with the displacement, with the displacement sensitivity of 0.1298 nm/mm and 0.1582 nm/mm for UFBG and AFBG respectively. Relatively speaking, the reflection spectrum of UFBG is more sensitive to the change of non-uniform strain distribution, which is beneficial to the sensing based on spectral shape, while AFBG shows a certain inhibitory or immune effect, which is beneficial to the sensing based on the central wavelength. In addition, in order to improve sensitivity and realize temperature compensation, the double FBG sensing method is selected for displacement measurement. The experimental results show that the displacement measurement sensitivity of double UFBG spectral bandwidth is 0.2826 nm/mm, and the displacement measurement sensitivity of double AFBG central wavelength difference is 0.3142 nm/mm.