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在非互易Su-Schrieffer-Heeger (SSH) 链中，电子在胞内的跳跃振幅依赖于其跳跃方向，因而，该非厄密SSH链同时存在非平庸拓扑边缘态和非厄密趋肤效应. 相应地，如何探测非厄密SSH链的边缘态和趋肤效应成为非厄密物理学的一个重要课题. 本文研究了非厄密SSH链的非平庸拓扑边缘态和非厄密趋肤效应对其零能附近电子输运特性的依赖关系. 研究发现当电子在零能附近透射率峰的峰值远小于1时，非厄密SSH链具有左趋肤效应；反之，零能附近电子透射率峰的峰值远大于1时，非厄密SSH链则具有右趋肤效应. 特别是，在非平庸拓扑边缘态区域内，非厄密SSH链的趋肤效应被进一步增强. 另外，当非厄密SSH链与左、右导线之间的电子隧穿耦合强度由弱到强改变时，零能附近电子反射率谷的数目将从2个变为0，此特性可以用来探测非厄密SSH链具有非平庸拓扑边缘态. 上述结果在理论上为探测非厄密SSH链的非平庸拓扑边缘态和非厄密趋肤效应类型提供了一种可选择的方案.
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关键词:
- 边缘态 /
- 非厄密趋肤效应 /
- 非厄密Su-Schrieffer-Heeger链 /
- 反射率 /
- 透射率
In the non-reciprocal Su-Schrieffer-Heeger (SSH) chain, the hopping amplitude of an electron in the intra-cell depends on its hopping direction. Consequently, the non-Hermitian SSH chain has both non-trivial topological edge states and non-Hermitian skin effect. However, how to detect the non-trivial topological edge states and non-Hermitian skin effect have become an important topics in non-Hermitian physics. In this paper, we have studied the dependences of the non-trivial topological edge states and the non-Hermitian skin effect of non-Hermitian SSH chain on their electron transport properties in the vicinity of the zero energy. It is demonstrated that when the peak value of the electron transmission probability in the vicinity of the zero energy is much smaller than 1, the non-Hermitian SSH chain has a left-non-Hermitian skin effect; while that in the vicinity of the zero energy is much larger than 1, the non-Hermitian SSH chain has a right-non-Hermitian skin effect. In particular, the skin effect of non-Hermitian SSH chain can be further enhanced in the region of non-trivial topological edge states. Moreover, with increasing the electron tunneling coupling amplitudes between the non-Hermitian SSH chain and the left and right leads from the weak coupling regime to the strong coupling one, the number of the dips of reflection probability in the vicinity of the zero energy will change from two to zero. Therefore, these results theoretically provide an alternative scheme for detecting non-trivial topological edge states and non-Hermitian skin effect types of the non-Hermitian SSH chain.-
Keywords:
- edge states /
- non-Hermitian skin effect /
- non-Hermitian Su-Schrieffer-Heeger chain /
- reflection probability /
- transmission probability
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