近日，美国加州大学的David M.Weld及其研究团队取得一项新进展。经过不懈努力，他们揭示kicked准晶体中的反常局域化现象。相关研究成果已于2024年1月17日在国际知名学术期刊《自然—物理学》上发表。

该研究团队在kicked准晶体相图的大范围内观察到了反常输运的实验现象。研究人员预测系统的哈密顿量具有丰富的相图，其中包括完全定域和完全离域相，以及一个由定域、离域和多重分形态嵌套模式组成的扩展区域，这导致了异常输运。该研究的冷原子实现通过新的Floquet工程技术完成，将可访问的相图扩展了五个数量级。研究人员在整个相图中映射输运性质，观察到了无序驱动的再入离域和次弹道输运，并基于特征态多重分形对这些现象给出了理论解释。

据悉，量子输运能够区分物质的动力学相。例如，弹道传播的特点在于没有无序，而多体局域相中的粒子不会以指数方式长时间传播。此外，物质还可能表现出反常输运的状态，其中粒子以非平凡指数传播。

附：英文原文

Title: Anomalous localization in a kicked quasicrystal

Author: Shimasaki, Toshihiko, Prichard, Max, Kondakci, H. Esat, Pagett, Jared E., Bai, Yifei, Dotti, Peter, Cao, Alec, Dardia, Anna R., Lu, Tsung-Cheng, Grover, Tarun, Weld, David M.

Issue&Volume: 2024-01-17

Abstract: Quantum transport can distinguish between dynamical phases of matter. For instance, ballistic propagation characterizes the absence of disorder, whereas in many-body localized phases, particles do not propagate for exponentially long times. Additional possibilities include states of matter exhibiting anomalous transport in which particles propagate with a non-trivial exponent. Here we report the experimental observation of anomalous transport across a broad range of the phase diagram of a kicked quasicrystal. The Hamiltonian of our system has been predicted to exhibit a rich phase diagram, including not only fully localized and fully delocalized phases but also an extended region comprising a nested pattern of localized, delocalized and multifractal states, which gives rise to anomalous transport. Our cold-atom realization is enabled by new Floquet engineering techniques, which expand the accessible phase diagram by five orders of magnitude. Mapping transport properties throughout the phase diagram, we observe disorder-driven re-entrant delocalization and sub-ballistic transport, and we present a theoretical explanation of these phenomena based on eigenstate multifractality.

DOI: 10.1038/s41567-023-02329-4

Source: https://www.nature.com/articles/s41567-023-02329-4