Stability Diagrams of a Bose-Einstein Condensate in a Periodic Array of Quantum Wells

With the help of a set of exact closed-form solutions to the stationary Gross Pitaevskii equation, we compre-hensively investigate Landau and dynamical instabilities of a Bose-Einstein condensate in a periodic array of quantum wells. In the tight-binding limit, the anaiyticai expressions for both Landau and dynamical instabilities are obtained in terms of the compressibility and effective mass of the BEC system. Then the stability phase diagrams are shown to be similar to the one in the case of the sinusoidal optical lattice.     

液晶相位调制型声光成像光谱偏振测量研究

新型的声光可调滤波器和双液晶相位可调延迟器相结合的一次成像光谱偏振系统与传统的二次成像光谱系统相比,不仅具有通光孔径大、光利用率高和全系统电调谐等优点,而且还能同时满足AOTF和LCVR的小角度入射,大大提高了光谱测量精度和偏振测量精度。通过实验计算,用拟合修正后的波长0和驱动频率fa关系式进行光谱测量,其相对误差值比用理论公式进行测量时减小约一个数量级。并且只需4组相位延迟量和4幅强度图即可求出全部的斯托克斯Stokes参量。理论分析了当系统考虑入射角度时,其偏振度、线偏振度、圆偏振度和角偏振度的最大相对误差值比只考虑光垂直入射时分别减少约0.306%、0.130%、10.96%和3.783%,为进一步提高系统的测量精度提供了理论基础。