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arXiv 0901.3125cond-mat.dis-nncond-mat.stat-mech
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laser散斑势的李雅普诺夫指数:弱无序展开

Lyapunov exponent for the laser speckle potential: a weak disorder expansion

E. Gurevich, O. Kenneth

摘要:

最近用激光散斑势实现的弱1D无序中的冷原子观察到物质波的安德森局域化[J.Billy等人,Nature 453,891(2008)]。后者的特殊之处在于它不具有高于特定截止$q_{c}$的空间频率分量。结果,李雅普诺夫指数(LE),或逆本地化长度,在粒子波矢量$k>{1/2}q_{c}$的玻恩近似中消失,和更高的阶变得必要。这些条款,高达四阶,计算分析和数值模拟相比。对于非常弱的无序,LE在$k$ $={1/2}q_{c}$处表现出急剧下降。对于中度无序(a),下降比从四阶近似预期的要小,并且(b)LE变得对无序偏斜度的符号非常敏感(这可以在冷原子实验中控制)。这两个观测结果都与散斑强度的强非高斯特性有关。

英文摘要:

Anderson localization of matter waves was recently observed with cold atoms in a weak 1D disorder realized with laser speckle potential [J. Billy et al., Nature 453, 891 (2008)]. The latter is special in that it does not have spatial frequency components above certain cutoff $q_{c}$. As a result, the Lyapunov exponent (LE), or inverse localization length, vanishes in Born approximation for particle wavevector $k>{1/2}q_{c}$, and higher orders become essential. These terms, up to the order four, are calculated analytically and compared with numerical simulations. For very weak disorder, LE exhibits a sharp drop at $k$ $={1/2}q_{c}$. For moderate disorder (a) the drop is less dramatic than expected from the fourth order approximation and (b) LE becomes very sensitive to the sign of the disorder skewness (which can be controlled in cold atom experiments). Both observations are related to the strongly non-Gaussian character of the speckle intensity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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