Delocalization of a disordered bosonic system by repulsive interactions
Delocalization of a disordered bosonic system by repulsive interactions
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DOI：
10.1038/nphys1635
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发表时间：
2009-10
期刊：
影响因子：
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通讯作者：
B. Deissler;M. Zaccanti;G. Roati;C. D’Errico;M. Fattori;M. Modugno;G. Modugno;M. Inguscio
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文献类型：
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作者：
B. Deissler;M. Zaccanti;G. Roati;C. D’Errico;M. Fattori;M. Modugno;G. Modugno;M. Inguscio
澄清相互作用和无序的相互作用是理解许多量子系统的基础，包括多孔介质中的超流氦、颗粒和薄膜超导体……以及在无序介质中传播的光。玻色子系统的一个核心方面是无序和弱排斥性相互作用之间的竞争，前者倾向于使粒子局域化，而后者具有非局域化效应。由于在大多数可用的物理系统中，对无序和相互作用的独立控制的所需程度是不容易实现的，因此迄今为止还不可能对这种竞争进行系统的实验研究。在这里，我们使用在准周期晶格势中具有可调排斥相互作用的简并玻色气体来详细研究这种相互作用。我们通过研究波函数的平均局部形状、空间相关性和相位相干性来表征整个离域交叉。确定了三种不同的状态，并与理论期望，，，，，进行了比较：指数局域化的安德森玻璃和局部相干碎片的形成以及相干的扩展状态。这些结果提供了对弱排斥相互作用在无序玻色子系统中的作用的见解，但我们的方法也应该能够研究在强相关状态下具有相互作用的无序系统，，。
Clarifying the interplay of interactions and disorder is fundamental to the understanding of many quantum systems, including superfluid helium in porous media, granular and thin-film superconductors,,,and light propagating in disordered media,,. One central aspect for bosonic systems,,is the competition between disorder, which tends to localize particles, and weak repulsive interactions, which instead have a delocalizing effect. As the required degree of independent control of disorder and of interactions is not easily achievable in most available physical systems, a systematic experimental investigation of this competition has not so far been possible. Here we use a degenerate Bose gas with tunable repulsive interactions in a quasiperiodic lattice potential to study this interplay in detail. We characterize the entire delocalization crossover through the study of the average local shape of the wavefunction, the spatial correlations and the phase coherence. Three different regimes are identified and compared with theoretical expectations,,,,,: an exponentially localized Anderson glass and the formation of locally coherent fragments as well as a coherent, extended state. These results provide insight into the role of weak repulsive interactions in disordered bosonic systems, but our approach should also enable investigations of disordered systems with interactions in the strongly correlated regime,,.