We investigate signatures of non-ergodic behavior in the real-time evolution of a one-dimensional Bose-Hubbard model, where the initial state is a doubly occupied density-wave state. We show that the occupation dynamics at strong interactions is dominated by doublon-holon exchange which leads to a domain wall excitation and propagation. The latter manifests as a negated staggered pattern in the density-density correlations. While the single-particle and the pair correlation functions show highly localized correlations that decay rapidly away from the nearest neighbor. We show that the time scale of the domain-wall excitations depends on the inverse of the interaction strength and therefore dictates the slow relaxation dynamics. In the presence of a parabolic trap, the occupation dynamics at the edges become frozen and further suppresses the propagation of correlations. This suppression happens even for trap strengths weaker than the tunneling rate. We also show that the model can be mapped to an antiferromagnetic transverse-field Ising model in the limit of strong interactions and that the correlation-propagation velocity in the original model is well captured by the group velocity of the spin-wave excitation in the effective spin model.
Interference-Induced Suppression of Doublon Transport and Prethermalization in the Extended Bose-Hubbard Model
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所凝聚态物理国家重点实验室）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Beijing Key Laboratory of Fault-Tolerant Quantum Computing, Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院容错量子计算北京市重点实验室）；Hefei National Laboratory（合肥国家实验室）；Songshan Lake Materials Laboratory（松山湖材料实验室）
Enhancement of chaotic subdiffusion in disordered ladders with synthetic gauge fields
本文研究了由人工规范场诱导的时间反演对称性破缺的无序非线性阶梯中的扩展波包。该模型在平均场近似下描述了无序驱动光梯中相互作用玻色子的动力学。波包的二阶矩$m_{2} = g t^α$以类似于时间反演情况的普适指数$α\simeq 1/3$亚扩散地增长。然而，前因子$g$强烈修改的电场强度，并显示出非单调依赖。对于弱场，前因子增加，因为时间反演增强后向散射被抑制。对于强场，线性波动方程的谱通过形成带隙和窄带来减小局域化长度。因此，抑制了次扩散律的前因子。
Transport of Hubbard-Band Quasiparticles in Disordered Optical Lattices
被困在光晶格中的量子简并气体是基础物理学的理想实验平台，因为这些系统是可调谐的，良好的特性，并与环境隔离。受控无序可以被引入来探索在没有常规失相机制（如声子）的情况下量子扩散的抑制，这在电子固体实验中是不可避免的。最近的实验使用简并费米气体在光晶格中的传输（Kondov等人，Phys. Rev. Lett. 114，083002（2015））来探测强相互作用的特别极端的状态，其可以被建模为Anderson-哈伯德模型。这些实验发现了一个有趣的绝缘相的证据，其中量子扩散被强无序完全抑制。这些实验的定量解释仍然是一个悬而未决的问题，需要包括非零熵，强相互作用，和捕获。我们认为，传输的抑制可以被认为是哈伯德带准粒子的本地化。我们建立了一个适用于囚禁光晶格实验的哈伯德带准粒子输运理论。我们比较的理论直接与Kondov等人的中心的质量输运实验。没有拟合参数。理论和实验之间的密切协议表明，传输的抑制只是部分由于有限熵效应。我们认为输运的完全抑制与Hubbard带准粒子的安德森局域化是一致的。我们的理论框架和光晶格实验的结合为研究孤立多体量子系统中的局域化提供了一个重要的平台。
