Singlet fission can circumvent energy-loss and improve the photoelectric conversion efficiency of solar cells. The excited state dynamics of rubrene analogueue C38H24S2 in toluene solution under different excitation conditions is investigated using femtosecond time-resolved transient absorption spectroscopy. Under the excitation of 550 nm and 365 nm, the excited singlet excitons collide with ground state molecules, and the correlated triplet pairs are generated at 8.2 ps and 3 ps, respectively. However, no independent triplet state signal is observed with the excitation wavelength of 550 nm. While under the excitation of 365 nm, the induced absorption signal of the triplet pair shifts, and the absorption of independent triplet exciton is observed around the detection wavelength of 550 nm. Besides, the singlet fission is observed by using the singular value decomposition method in the transient absorption spectrum with the excitation wavelength of 460 nm.

In order to accurately determine the refractive index of capsule, a method for measuring the refractive index of capsules is established based on the combination of white light vertical scanning interference (VSI) and white light reflectance spectra (WLRS). To solve the problems such as the difficulty to accurately determinate the peak positions and the possible interference order error in white reflectance spectra, the data processing method, in which the curve fitting is used to determine the peak positions and the interference order is determined by the continuity of interference order, is applied. The measurement, experimental verification and uncertainty analysis of the refractive index of glasscapsule are carried out. It is shown that the refractive index of capsule can be measured accurately by white light interference technique, and the measurement uncertainty is about 0.86%.

Aiming at the problem that the traditional scale-invariant feature transform (SIFT) algorithm has a large amount of calculation in the process of image stitching, a fast SIFT stitching algorithm based on phase correlation and texture classification is proposed. Firstly, by using the phase correlation method, the overlapping regions of the input images to be stitched are roughly obtained. Secondly, images are classified with texture and the area with higher texture complexity is selected for SIFT detection. In order to improve the speed of texture classification, an interval classification approach is proposed. Finally, the feature points are matched only in the regions with the same texture complexity for different complexity texture regions. The experimental results show that compared with the traditional SIFT algorithm and the two existing improved SIFT algorithms, the improved algorithm in this work not only maintains good stitching quality, but also improves the average stitching speed by 68.46%, 20.45%, 41.83%, respectively. Therefore, the proposed algorithm has the potential application value in the field of high stitching efficiency requirements.

The light source mentioned in recent quantum radar scheme, in which the quantum entanglement effect of entangled photons is used to realize three-dimensional quantum enhancement, has been analyzed andthe possible solution is also discussed. In the new quantum radar scheme, positive correlation in frequency and transverse momentum can be used to realize three-dimensional quantum enhancement. Taking two-photon states as an example, firstly, preparationof the positively correlated state of frequency or momentum is investigated separately, and then on this basis, the preparation of entangled photon sources with positive correlation of both frequency and momentum is further discussed. Numerical simulation shows that through a spontaneous parametric down conversion process, the entangled photon source with positive correlation in frequency and transverse momentum can be generated by using a tightly focused pulsed pump light.

Laser self-mixing technique has the advantages of high sensitivity, easy collimation and non-contact measurement. In a multi-longitudinal mode laser self-mixing interference system, the self-mixing signal waveform changes periodically with the external cavity length. According to this physical phenomenon, a novel scheme for measuring the free spectral range (FSR) of laser using a three-longitudinal mode laser self-mixing vibration sensing system is proposed. Combined with the interference mixing theory and three-mirror cavity theory, the theoretical model of measuring laser FSR based on a three longitudinal mode laser self-mixing vibration sensing system is established for the first time, and the corresponding numerical simulation is carried out. Results show that the FSR of the pigtailed laser diode is affected by the external environment, and its variation range is from 163.93 GHz to 175.64 GHz. The displacement resolution and frequency resolution of the system is 0.01 mm and 1.91 GHz respectively. Due to the excellent merits of high resolution, compactness and low-cost, it is expected that the system can be applied to FSR measurement of various types of lasers.

Shortly after the advent of lasers, researchers began to use coherent beam combination techniques to achieve high energy output of laser systems. Passive coherent combination technology have the characteristics of simple structure, expandablility and the ability to realize phase locking between single lasers by using the self-organization of the system, so it has attracted much attention in the field of high-energy laser. Passive coherent beam combination schemes based on all-fiber structure, multi-core fiber structure, self-image external-cavity structure and ring cavity structure and the related research progress are introduced, and the advantages and disadvantages of these schemes are summarized. In coherent beam combination technology, coherent efficiency and brightness are two important parameters to evaluate the coherent combination effect.

A scheme for preparing three-atom W state via nonresonant interaction between Ξ-type three-level Rydberg atoms and a single-mode cavity in cavity quantum electrodynamics (QED) is proposed. The scheme requires three three-level atoms and one single-mode cavity. The cavity field is initially in the vacuum state, the first and second atoms interacting with the cavity are initially in the excited state, while the third atom is in the ground state. The practical feasibility of the scheme and the influence of detuning δ on fidelity are analyzed and discussed. Numerical calculation demonstrates that the fidelity and the corresponding success probability of the entangled state is different when the atom-field interaction time is different, and W states with maximized fidelity can be obtained by choosing the appropriate interaction time. It is also shown that in the case of different coupling constants, the effect of detuning δ on fidelity is different. According to this work, it is shown that the scheme can be generalized to prepare W state with arbitrary weight.

Quantum digital signature (QDS) can guarantee the integrity and non-repudiation of messages with quantum mechanics-based information-theoretical security. Currently, most researches are concentrated on multi-decoy state QDS protocol. However, due to the existence of statistical fluctuations, the performance of multi-decoy state QDS systems could be deteriorated. In order to improve the performance of QDS, a 1-decoy state QDS protocol is proposed, and the corresponding security analysis and numerical simulation of its performance are also given. The signature rates with parameter optimization for 1-decoy state protocol and 2-decoy state protocol are compared through numerical simulation. It is shown that 1-decoy state protocol can improve the signature rate of the system a little under most transmission distance. In addition, 1-decoy state protocol is easier to be implemented, making it more practical and promising in possible digital signature scenarios.

By using Huybrechts′ linear combination operator and the second Lee-Low-Pines (LLP) unitary transformation method, the properties of the strong-coupling polaron in RbCl asymmetrical semi-exponential quantum well are investigated. The vibrational frequency and ground state energy of the strong-coupling polaron in a RbCl asymmetrical semi-exponential quantum well are obtained, and the variation of the vibrational frequency and ground state energy with the two positive parameters (U0 and σ) of the asymmetrical semi-exponential confinement potential is derived theoretically. RbCl crystal material is selected for numerical calculation, and the results indicate that U0 and σ are important physical quantities for investigating the properties of the strong-coupling polaron in asymmetrical semi-exponential quantum well, and the vibrational frequency and ground state energy of the strong-coupling polaron increase with the increase of U0, while decrease with the increase of σ.

The dynamic evolution of the average fidelity of quantum teleportation is investigated using quantum-state-diffusion (QSD) theory when two interacting qubits strongly coupled to a bosonic bath. The effects of environmental memory, anisotropic coupling parameters, Dzyaloshinskii-Moriya (DM) interaction and external magnetic field on quantum teleportation are analyzed and discussed. Results show that the memory effect of the environment can effectivelyimprove the average fidelity. When the quantum channel is maximum entangled state, the optimal average fidelity can be obtained by increasing the coupling parameters, DM interaction or the external magnetic field. However, when the quantum channel is changed, the effect of the coupling constant between qubits on average fidelity is opposite. It indicates that the combination of the non-Markovian memory effect and optimal parameter can be used to achieve ideal quantum teleportation in theory.

The definition of the Hamiltonian and mean magnetization of XXZ open and closed spin chain of Heisenberg model in one-dimension is given, then the ground state, excited state energy and mean magnetization of the XXZ Heisenberg model of the open and closed spin chain in one dimension are calculated under different parameters and different configuration ［N,k］. At last, the correlation degree and phase transition of XXZ open and closed spin chain of Heisenberg model in one-dimension are analyzed comparatively according to the calculation results. Results show that the correlation degree is embodied very well when the energy difference between the ground state and the excited state change along with the parameter or configuration ［N,k］. The phase transition point of the system can be found according to the inflection point that the ground state energy changes along with the change of the parameter and the degeneracy that the energy difference between the excited state and the ground state changes with the parameter. It is also shown that the calculation results of the open and closed spin chain are same roughly, however, the calculation effect of the closed chain model is more intuitive and obvious than that of the open chain model. The correlation properties and phase transition of the XXZ open and closed spin chain of Heisenberg model in one-dimension are compared, which provides an important reference for further understanding the quantum correlation properties of Heisenberg model.

Monogamy of entanglement is an important property in quantum entanglement, which can be used to characterize the entanglement structure in multipartite systems. Tsallis-q entropy entanglement is a well-known entanglement measure and the squared Tsallis-q entropy entanglement obeys a monogamy relation. The entanglement monogamy relation satisfied by the μ-th power of squared Tsallis-q entropy entanglement for μ2 has been proved by Yuan etal, and a new monogamy relationship for squared Tsallis-q entropy entanglement is presented here, which is tighter than that have been proven previously.

A memristive chaotic system is proposed by adding terms with properties of memristor and other nonlinear terms to Yang system. The chaotic attractors with single scroll, double scrolls and triple scrolls can be obtained by changing the parameters and initial values of state variables of the system. The dynamic characteristics of the system are analyzed, and the generalized synchronization between the memristive chaotic system and Chen system with disturbance is investigated by taking a triple-scroll system as an example. The synchronization controller and parameter adaptive law are designed by employing sliding mode control method, and the sufficient conditions for synchronization are obtained by using Lyapunov stability theory. Finally, the proposed synchronization method is compared with the method without sliding mode control. Results show that the two systems are synchronized and the parameters are accurately estimated. The proposed method is faster in synchronization speed than the method without sliding mode control, and has better anti-interference ability as well.

The average bit error rate (BER) and outage probability of circular polarization shift key (CPOLSK) modulation under the combined effect channel of atmospheric turbulence and pointing errors are investigated by using aperture averaging technique. The closed expressions of BER and outage probability are derived by using Meijer G function. The influences of normalized beamwidth, normalized jitter and receiver aperture size on the average BER and outageprobability are simulated, and numerical analysis is also carried out. And then the BER performance of CPOLSK modulation is compared with that of on-off keying (OOK) modulation. All numerical simulation results are verified by Monte-Carlo simulation. Results show that the BER performance of CPOLSK modulation is better than OOK modulation under the same conditon, and the influence of normalized beam width on system performance is nonlinear and there is an optimal value. It is also shown that with the increase of the normalized jitter standard deviation, the performance of the system will decrease, while increasing the receiving aperture size can effectively improve the performance of the system. The results are of practical significance for the design of FSO communication system.

Heavy metal pollutants in atmospheric aerosols can adversely affect ecosystem and even human body. Therefore, it is necessary to detect and analyze the heavy metal pollutants in aerosols. Using laser-induced breakdown spectroscopy (LIBS), qualitative analysis of metallic elements and quantitative analysis of toxic heavy metals in atmospheric aerosol collected in 20 minutes were carried out, and LIBS analysis spectrum of Cr in aerosols under this experimental system was mainly studied. Then the relationship between the intensity of Cr in atmospheric aerosols and the contents of PM2.5 and PM10 published by China Environmental Monitoring Station was studied by normalization. Moreover, by establishing the calibration curve of heavy metal elements, the content of heavy metal elements in the aerosol samples was detected, and the corresponding detection limit was calculated. The experimental results show that atmospheric aerosols contain metal elements such as Cr, Na, Mg, Al, Ca, Fe, and Ba, and the intensity of the Cr element line is positively correlated with the PM2.5 and PM10 data published by China National Environmental Monitoring Centre, especially with the PM2.5 data. The correlation coefficient R2 of the calibration curve for heavy metal elements established in this experiment ranges from 0.995 to 0.997, and the detection limit ranges from 1.9 to 3.6 mg/kg, which indicates that the method can be applied for rapid detection of the content of heavy metal elements in atmospheric aerosol.

In actual production, being affected by the manufacturing process, the reference voltage module inside the chip will have a certain deviation. During the chip mass production test, a kind of embeddedmemory unit trimming circuit is used to write trim code to control the chip’s internal circuits and fine-tune the parameters of the chip. As there are some factors that cause the test to fail during the test, retests are needed to improve the yield. However, if the traditional programming method is used for one time programmable (OTP) programming, the trim and program will be incorrectly programmed due to repeated programming during mass production testing, which will result in chip failure. Therefore, an improved OTP tuning algorithm is designed based on the automatic test equipment (ATE), which measures the initial voltage and frequency, and then tests and corrects the most appropriate trim code to avoid the repeated burning of OTP on the chip during retest. The proposed algorithm can improve the chip and reduce the production costs as well. The feasibility of the algorithm is verified by analyzing the test results of 8000 die on two wafers.