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arXiv 2104.10364cond-mat.mes-hallphysics.optics
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光子拓扑安德森绝缘体

Photonic Topological Anderson Insulators

Simon Stützer, Yonatan Plotnik, Yaakov Lumer, Paraj Titum, Netanel Lindner, Mordechai Segev, Mikael C. Rechtsman, Alexander Szameit

摘要:

二维拓扑材料的标志性特性是量子化霍尔电导率对无序的难以置信的鲁棒性。这种鲁棒性源于这样一个事实,即在拓扑带隙中,传输只能沿着边缘模式发生,而边缘模式不受散射影响。然而,对于足够强的无序,带隙关闭,系统变得拓扑平凡,因为所有的状态变得本地化,使得所有的传输消失-根据安德森局域化。因此,当有人提出,对于二维量子自旋霍尔拓扑系统,可能会发生相反的情况时,人们感到惊讶。在所谓的拓扑安德森绝缘体中,受保护的边缘态和量子化输运的出现是由无序的引入引起的。然而,迄今为止,拓扑安德森绝缘体相的观察一直难以捉摸。在这篇文章中,我们报告的拓扑安德森绝缘体的第一个实验演示。我们在光子实现中做到了这一点:在失谐蜂窝几何形状中的螺旋形渐逝耦合波导阵列。在适当的条件下,增加现场无序,在定义波导的折射率对比度的随机变化的形式,驱动系统从平凡的阶段到拓扑状态。

英文摘要:

The hallmark property of two-dimensional topological materials is the incredible robustness of the quantized Hall conductivity to disorder. That robustness arises from the fact that in the topological band gap, transport can occur only along the edges modes, which are immune to scattering. However, for sufficiently strong disorder, the band gap closes and the system becomes topologically trivial as all states become localized, such that all transport vanishes -- in accordance with Anderson localization. It therefore came as a surprise when it was suggested that, for a two-dimensional quantum spin-Hall topological system, the opposite could occur. In so-called topological Anderson insulators, the emergence of protected edge states and quantized transport is caused by the introduction of disorder. However, to date, the observation of the topological Anderson insulator phase has been elusive. In this article, we report the first experimental demonstration of a topological Anderson insulator. We do that in a photonic implementation: an array of helical, evanescently-coupled waveguides in a detuned honeycomb geometry. Under proper conditions, adding on-site disorder, in the form of random variations in the refractive index contrast defining the waveguides, drives the system from a trivial phase into a topological state.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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