Regimes of classical transport of cold gases in a two-dimensional anisotropic disorder
Regimes of classical transport of cold gases in a two-dimensional anisotropic disorder
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二维各向异性无序中冷气体的经典传输机制
DOI：
10.1088/1367-2630/13/9/095015
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发表时间：
2011
影响因子：
3.3
通讯作者：
L. Sanchez
中科院分区：
文献类型：
--
作者：
Luca Pezzè;M. Robert;T. Bourdel;J. Brantut;B. Allard;T. Plisson;A. Aspect;P. Bouyer;L. Sanchez
我们数值研究了二维无序势场中冷原子的动力学。我们考虑了各向异性的散斑势，并着重于经典动力学，这是相关的一些最近的实验。首先，我们研究了具有固定能量的粒子的行为，并确定了不同的输运机制。在低能量下，由于没有扩散团簇，粒子是经典局域的。在高能量下，粒子进行正常扩散，我们表明，扩散系数的尺度代数与粒子的能量，与各向异性因子，这是显着不同的无序势。在中等能量，我们发现一个瞬态的亚扩散制度，这是有关的典型实验的时间尺度。第二，在上述结果的基础上，我们研究了具有任意能量分布的冷原子气体的行为。我们表明，在扩散制度的原子云的密度分布是强烈的峰值，特别是，它不是高斯。它在大距离的行为，使我们能够提取的能量依赖的扩散系数从实验密度分布。对于释放到无序势的热云，我们表明，我们的数值预测与实验结果一致。本文不仅给出了最近的实验结果的见解，但它也可能有助于解释未来的实验寻找偏离经典扩散和痕迹的安德森本地化。
We numerically study the dynamics of cold atoms in a two-dimensional disordered potential. We consider an anisotropic speckle potential and focus on the classical dynamics, which is relevant to some recent experiments. Firstly, we study the behavior of particles with a fixed energy and identify different transport regimes. At low energy, the particles are classically localized due to the absence of a percolating cluster. At high energy, the particles undergo normal diffusion, and we show that the diffusion coefficients scale algebraically with the particle energy, with an anisotropy factor that is significantly different from that of the disordered potential. At intermediate energy, we find a transient sub-diffusive regime, which is relevant to the time scale of typical experiments. Secondly, we study the behavior of a cold atomic gas with an arbitrary energy distribution, using the above results as the groundwork. We show that the density profile of the atomic cloud in the diffusion regime is strongly peaked and, in particular, that it is not Gaussian. Its behavior at large distances allows us to extract the energy-dependent diffusion coefficients from experimental density distributions. For a thermal cloud released into the disordered potential, we show that our numerical predictions are in agreement with experimental findings. Not only does this paper give insights into recent experimental results, but it may also help in the interpretation of future experiments searching for deviation from classical diffusion and traces of Anderson localization.