Fermionic transport and out-of-equilibrium dynamics in a homogeneous Hubbard model with ultracold atoms
Fermionic transport and out-of-equilibrium dynamics in a homogeneous Hubbard model with ultracold atoms
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DOI：
10.1038/nphys2205
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发表时间：
2012-01
期刊：
影响因子：
19.6
通讯作者：
U. Schneider;L. Hackermüller;Jens Philipp Ronzheimer;S. Will;Simon Braun;T. Best;I. Bloch;E. Demler;S. Mandt;D. Rasch;A. Rosch
中科院分区：
文献类型：
--
作者：
U. Schneider;L. Hackermüller;Jens Philipp Ronzheimer;S. Will;Simon Braun;T. Best;I. Bloch;E. Demler;S. Mandt;D. Rasch;A. Rosch
输运性质是凝聚态物理中许多重要阶段的定义特征之一。在存在强相关性的情况下，它们很难预测，即使对于哈伯德模型这样的模型系统也是如此。在实际材料中，由于杂质、晶格缺陷或多带效应，会出现额外的复杂情况。相比之下，超冷原子提供了在清洁和可控环境中研究输运和失衡现象的可能性，因此可以作为凝聚态系统的量子模拟器。在这里，我们研究了初始受限的费米子量子气体在均匀光学晶格的最低能带中的展开。对于非相互作用的原子，我们观察到了弹道输运，但即使是很小的相互作用也使膨胀几乎是双峰的，膨胀速度大大降低。动力学与相互作用的符号无关，揭示了哈伯德模型的一种新颖的动态对称性。
Transport properties are among the defining characteristics of many important phases in condensed-matter physics. In the presence of strong correlations they are difficult to predict, even for model systems such as the Hubbard model. In real materials, additional complications arise owing to impurities, lattice defects or multi-band effects. Ultracold atoms in contrast offer the possibility to study transport and out-of-equilibrium phenomena in a clean and well-controlled environment and can therefore act as a quantum simulator for condensed-matter systems. Here we studied the expansion of an initially confined fermionic quantum gas in the lowest band of a homogeneous optical lattice. For non-interacting atoms, we observe ballistic transport, but even small interactions render the expansion almost bimodal, with a dramatically reduced expansion velocity. The dynamics is independent of the sign of the interaction, revealing a novel, dynamic symmetry of the Hubbard model.