A Quantum Watermarking Protocol Based on Bell Dual Basis

This paper presents a Bell-dual-basis-based quantum watermarking protocol composed of three major algorithms: watermark embedding and extracting and the intercepting test. The first two are completed by using the entanglement swapping property of Bell dual basis and the test is accomplished through IBF protocol to guarantee its bottom security. The watermarking protocol is mainly designed for the protection of digital copyright in the existence of classical information. This design finds that the quality of digital contents is not damaged with its zero-watermark attributes when embedding watermarks.     

Generation of stable and high-quality frequency-locked carriers based on improved re-circulating frequency shifter

An optical multicarrier generator based on the improved re-circulating frequency shifter (RFS) to generate a larger number of frequency-locked carriers with high-quality has been studied. By eliminating the third-order crosstalk components, the output carrier's number and optical signal-to-noise-ratio (OSNR) of the generator have been improved significantly. In addition, the maximum output OSNR and optimal radio-frequency drive voltages in the cases of different desired carrier numbers have been obtained. Using the improved configuration, 130-tone with high-quality (tone-to-noise ratio ～20 dB and superior flatness <3 dB) where the drive voltage is only around 0.5Vπ can be achieved. The simulation results show a good agreement with the theoretical analysis. The multicarrier generator based on the improved RFS has the potential application in the terabit superchannel optical transmission.     

A LabVIEW-based real-time measurement system for polarization detection and calibration

A rapid real-time polarization measurement system was designed and implemented in this paper. The system is centered round a computer running application developed for the purpose. The paper illustrates how to build such an excellent application with National Instruments’ graphical programming language LabVIEW, a synchronized high speed multi-channels data acquisition card and some photoelectric conversion module in detail. With simple and friendly user interface, the experimental result shows that the measurement system has high computational efficiency, high precision calibration matrix, which can be efficiently utilized in experiments relating to the measurement of polarization.     

Existence results for second-order system with impulse effects via variational methods

In this paper, we investigate the positive solutions of a second-order system with impulse effects. By using critical point theory the existence result of positive solutions is obtained.     

Rogue wave solutions for a generalized nonautonomous nonlinear equation in a nonlinear inhomogeneous fiber

In this paper, we investigate a generalized nonautonomous nonlinear equation which describes the ultrashort optical pulse propagating in a nonlinear inhomogeneous fiber. By virtue of the generalized Darboux transformation, the first- and second-order rogue-wave solutions for the generalized nonautonomous nonlinear equation are obtained, under some variable–coefficient constraints. Properties of the first- and second-order rogue waves are graphically presented and analyzed: When the coefficients are all chosen as the constants, we can observe the some functions, the shapes of wave crests and troughs for the first- and second-order rogue waves change. Oscillating behaviors of the first- and second-order rogue waves are observed when the coefficients are the trigonometric functions.     

Theoretical insights into the mechanism of photocatalytic reduction of CO2 over semiconductor catalysts

Photocatalytic reduction of CO₂ is one important approach to alleviate greenhouse gas emission and energy crisis, which has gained huge attention in the past decades. However, the lack of understanding complex reaction mechanism impedes new catalysts design. It is also very difficult to understand the mechanism by using only experimental approaches. For this concern, theoretical calculations can effectively supplement the experimental deficiency and thus play an important role. Recently theoretical calculations have been performed on adsorption, migration and reduction of CO₂ molecule on the photocatalyst surface, leading to useful information that have contributed greatly to this field. This review summarizes recent advances in first-principles calculations about CO₂ photoreduction over various semiconductor photocatalysts like metal oxides, sulfides and g-C₃N₄. The methods, models, adsorption and reaction pathways have been discussed in detail. The perspective about future investigation on the photocatalytic reduction of CO₂ using first principles calculations is also presented.