This paper compares the properties of silicon oxide and nitride as host matrices for Er ions.Erbium-doped silicon nitride films were deposited by a plasma-enhanced chemical-vapour deposition system.After deposition,the films were implanted with Er3+ at different doses.Er-doped thermal grown silicon oxide films were prepared at the same time as references.Photoluminescence features of Er3+ were inspected systematically.It is found that silicon nitride films are suitable for high concentration doping and the thermal quenching effect is not severe.However,a very high annealing temperature up to 1200° C is needed to optically activate Er3+,which may be the main obstacle to impede the application of Er-doped silicon nitride. 相似文献
Quantum watermarking technology protects copyright by embedding an invisible quantum signal in quantum multimedia data. This paper proposes a two-bit superposition method which embeds a watermark image (or secret information) into a carrier image. Firstly, the bit-plane is used to encrypt the watermark image. At the same time, the quantum expansion method is used to extend the watermark image to the same size with the carrier image, and then the image is encrypted through the Fibonacci scramble method again. Secondly, the first proposed method is the two bits of the watermark image which is embedded into the carrier image in accordance with the order of the high and lowest qubit, and the second proposed method which is the high bit of the watermark image is embedded to the lowest bit. Then the lowest bit of the watermark image is embedded in carrier image. Third, the watermark image is extracted through 1-CNOT and swap gates, and the watermark image is restored by inverse Fibonacci scramble, inverse expansion method and inverse bit-plane scramble method. Finally, for the validation of the proposed scheme, the signal-to-noise ratio (PSNR), the image histogram and the robustness of the two watermarking methods are analyzed.
In this exploratory study, near-threshold scattering of D and \begin{document}$\bar{D}^*$\end{document} meson is investigated using lattice QCD with \begin{document}$N_f=2+1+1$\end{document} twisted mass fermion configurations. The calculation is performed in the coupled-channel Lüscher finite-size formalism. The study focuses on the channel with \begin{document}$I^G(J^{PC})=1^+(1^{+-})$\end{document} where the resonance-like structure \begin{document}$Z_c(3900)$\end{document} was discovered. We first identify the two most relevant channels and the lattice study is performed in the two-channel scattering model. Combined with the two-channel Ross-Shaw theory, scattering parameters are extracted from the energy levels by solving the generalized eigenvalue problem. Our results for the scattering length parameters suggest that for the particular lattice parameters that we studied, the best fit parameters do not correspond to the peak in the elastic scattering cross-section near the threshold. Furthermore, in the zero-range Ross-Shaw theory, the scenario of a narrow resonance close to the threshold is disfavored beyond the 3\begin{document}$\sigma$\end{document} level. 相似文献
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