论文标题
嵌入在特殊表面中的三阶特殊线的实现和拓扑特性
Realization and Topological Properties of Third-Order Exceptional Lines Embedded in Exceptional Surfaces
论文作者
论文摘要
作为Hermitian淋巴结结构的对应物，由特殊点（EPS）形成的几何形状（例如特殊线（ELS））需要有趣的光谱拓扑。我们报告了完全嵌入在三维周期性合成动量空间中的订单2例外表面（ES2）中的3阶特殊线（EL3）的实验实现。 EL3和伴随的ES2，以及基础空间的拓扑结构，禁止通过普遍的拓扑表征方法评估其在特征值歧管中的拓扑。我们通过定义与哈密顿人的结果相关联的缠绕数字来解决这个问题。最终的绕组数检测到EL3，但忽略了ES2，可以诊断出EL3携带的拓扑电流，从而可以预测其在扰动下的进化。我们的结果例证了高阶特殊几何形状的前所未有的拓扑，并可能激发新的非热拓扑应用。
As the counterpart of Hermitian nodal structures, the geometry formed by exceptional points (EPs), such as exceptional lines (ELs), entails intriguing spectral topology. We report the experimental realization of order-3 exceptional lines (EL3) that are entirely embedded in order-2 exceptional surfaces (ES2) in a three-dimensional periodic synthetic momentum space. The EL3 and the concomitant ES2, together with the topology of the underlying space, prohibit the evaluation of their topology in the eigenvalue manifold by prevailing topological characterization methods. We resolve this issue by defining a winding number that associates with the resultants of the Hamiltonian. This resultant winding number detects EL3 but ignores the ES2, allowing the diagnosis of the topological currents carried by the EL3, which enables the prediction of their evolution under perturbations. Our results exemplify unprecedented topology of higher-order exceptional geometries and may inspire new non-Hermitian topological applications.
