Quantum key distribution transmitter chip based on hybrid-integration of silica and lithium niobates

A quantum key distribution transmitter chip based on hybrid-integration of silica planar light-wave circuit (PLC) and lithium niobates (LN) modulator PLC is presented. The silica part consists of a tunable directional coupler and 400-ps delay line, and the LN part is made up of a Y-branch, with electro-optic modulators on both arms. The two parts are facet-coupled to form an asymmetric Mach-Zehnder interferometer. We successfully encode and decode four BB84 states at 156.25-MHz repetition rate. Fast phase-encoding of 0 or $\pi $ is achieved, with interference fringe visibilities 78.53% and 82.68% for states $|+\rangle$ and $|-\rangle$, respectively. With the aid of an extra off-chip LN intensity modulator, two time-bin states are prepared and the extinction ratios are 18.65 dB and 15.46 dB for states $|0\rangle$ and $|1\rangle$, respectively.     

Temperature characterizations of silica asymmetric Mach-Zehnder interferometer chip for quantum key distribution

Quantum key distribution (QKD) system based on passive silica planar lightwave circuit (PLC) asymmetric Mach-Zehnder interferometers (AMZI) is characterized with thermal stability, low loss and sufficient integration scalability. However, waveguide stresses, both intrinsic and temperature-induced stresses, have significant impacts on the stable operation of the system. We have designed silica AMZI chips of 400 ps delay, with bend waveguides length equalized for both long and short arms to balance the stresses thereof. The temperature characteristics of the silica PLC AMZI chip are studied. The interference visibility at the single photon level is kept higher than 95% over a wide temperature range of 12 ℃. The delay time change is 0.321 ps within a temperature change of 40 ℃. The spectral shift is 0.0011 nm/0.1 ℃. Temperature-induced delay time and peak wavelength variations do not affect the interference visibility. The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations.     

框架结构多目标优化方法

提出了一种框架结构多目标优化方法。基于力法给出了框架结构的等效刚度、最大弯矩随结构材料、几何等设计参数的变化,利用动能等效给出了框架结构的等效质量,进而得到框架结构一阶固有频率随结构材料、几何等参数的变化,用有限元方法验证了所得频率、弯矩公式的正确性。以固有频率、最大弯矩为优化目标函数构造框架结构的多目标优化模型,通过单目标优化得到频率、弯矩最优值,以单目标优化值为基础构造全局目标优化函数,将多目标优化转化为单目标优化。     

基于拉曼光谱的改进投影算法快速鉴别药品

投影算法常用于混合物分析中确定灰色体系是否存在未知干扰,而在用于药品鉴别时,由于其判定标准不充分,故不能同时准确鉴别不同药品和相似药品。提出将投影算法的判定标准(待测物质光谱的量测误差大小是否在限定水平)改进为待测物质光谱与标准物质光谱的量测误差大小水平是否相当、量测误差分布是否相近。将改进投影算法与未经改进投影算法用于六种(拜耳阿司匹林肠溶片、泰诺对乙酰氨基酚缓释片、拜耳复方对乙酰氨基酚片Ⅱ、华中复合维生素C片、华中维生素B片、吗丁啉多潘立酮片)不同药品的鉴别以及三种相似药品(拜耳阿司匹林肠溶片、上海信宜药阿司匹林肠溶片、巴米尔阿司匹林泡腾片)的区分,实验结果表明改进投影算法实现了不同药品的准确鉴别及相似药品的准确区分,准确率均高达100%,有望发展成为普适,可靠的自动化药品识别算法,并为基于拉曼光谱的物质识别算法研究提供参考依据。     

螺栓拉应力超声无损检测方法

本文依据声弹性原理中超声波传播速度与应力之间的对应关系,利用横波与纵波联合测量的办法,给出栓体长度未知的紧固螺栓轴向应力测量办法。针对螺栓在低载荷与高载荷不同情况下的栓体轴向应力测量系数不同的状况,分类进行了讨论,并给出对应载荷条件下应力测量系数的计算办法。文章讨论了A2-70奥氏体不锈钢与强度等级4.8低碳钢两种不从材质螺栓的轴向应力测量结果,实际测量与理论测量平均误差小于2.9367%,提高了横纵波轴向应力测量的精度。