论文标题
在非热门系统中，通过反对对称性保护所有非缺陷的双性变性
Protection of all nondefective twofold degeneracies by anti-unitary symmetries in non-Hermitian systems
论文作者
论文摘要
非热性变性性被归类为有缺陷且非缺陷的特殊点〜（EP）。在有缺陷的EPS中，特征值和特征力结合了，但非缺陷EP的特征仅是其特征值中的变性。还众所周知，所有变性性都是对称性保护的或偶然的。在本文中，我证明反对对称性保护所有非缺陷双EPS。通过开发一个2D非热结合模型，我证明了这些对称性是各种对称操作的综合，例如离散或空间点组对称性，以及WICK在非Hermitian参数空间中的旋转。引入这些复合对称性，我在模型的各种参数方面介绍了对非缺陷EPS的保护。这项工作为稳定非缺陷EPS的方式铺平了道路，并就了解非热带频道交叉路口提供了新的视角。
Non-Hermitian degeneracies are classified as defective and nondefective exceptional points~(EP). While in defective EPs, both eigenvalues and eigenenergies coalesce, nondefective EPs are characterized merely by the occurrence of degeneracies in their eigenvalues. It is also known that all degeneracies are either symmetry-protected or accidental. In this paper, I prove that anti-unitary symmetries protect all nondefective twofold EPs. By developing a 2D non-Hermitian tight-binding model, I have demonstrated that these symmetries are composite of various symmetry operations such as discrete or spatial point-group symmetries and Wick's rotation in the non-Hermitian parameter space. Introducing these composite symmetries, I present the protection of nondefective EPs in various parameter regimes of my model. This work paves the way to stabilizing nondefective EPs and offers a new perspective on understanding non-Hermitian band crossings.
