近日，德国莱布尼茨固体与材料研究所的Ion Cosma Fulga&Joseph Dufouleur及其研究团队取得一项新进展。经过不懈努力，他们观察到多终端量子霍尔器件中的非厄米拓扑现象。相关研究成果已于2024年1月18日在国际知名学术期刊《自然—物理学》上发表。

该研究团队利用量子霍尔边缘态的非互易性，而不是增益和损耗，直接观察到多终端量子霍尔环中的非厄米拓扑现象。实验中的输运测量显示了一个强大的非厄米集肤效应，其特点是电流和电压呈现指数分布，且在霍尔平台过渡过程中持续存在，远离最大非互易状态。他们对量子器件中非厄米拓扑结构的观察，为构建和研究一般的非厄米系统提供了一种可扩展的实验方法。

据悉，以非厄米拓扑为特征的量子器件在精密传感和信号放大方面，预计具有高度鲁棒性和潜在的有用特性。然而，实现这些器件仍然是一项艰巨的实验任务，因为非厄米性通常与增益和损耗有关，这需要精确调控以产生非平凡拓扑的特性。

附：英文原文

Title: Non-Hermitian topology in a multi-terminal quantum Hall device

Author: Ochkan, Kyrylo, Chaturvedi, Raghav, Knye, Viktor, Veyrat, Louis, Giraud, Romain, Mailly, Dominique, Cavanna, Antonella, Gennser, Ulf, Hankiewicz, Ewelina M., Bchner, Bernd, van den Brink, Jeroen, Dufouleur, Joseph, Fulga, Ion Cosma

Issue&Volume: 2024-01-18

Abstract: Quantum devices characterized by non-Hermitian topology are predicted to show highly robust and potentially useful properties for precision sensing and signal amplification. However, realizing them has remained a daunting experimental task, as non-Hermiticity is often associated with gain and loss, which would require precise tailoring to produce the signatures of non-trivial topology. Here, instead of gain and loss, we use the non-reciprocity of quantum Hall edge states to directly observe non-Hermitian topology in a multi-terminal quantum Hall ring. Our transport measurements evidence a robust, non-Hermitian skin effect, characterized by currents and voltages showing an exponential profile that persists across Hall plateau transitions away from the regime of maximum non-reciprocity. Our observation of non-Hermitian topology in a quantum device introduces a scalable experimental approach to construct and investigate generic non-Hermitian systems.

DOI: 10.1038/s41567-023-02337-4

Source: https://www.nature.com/articles/s41567-023-02337-4