Song Alex Y, Sun Xiao-Qi, Dutt Avik, Minkov Momchil, Wojcik Casey, Wang Haiwen, Williamson Ian A D, Orenstein Meir, Fan Shanhui
Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA.
Department of Physics, Stanford University, Stanford, California 94305, USA.
Phys Rev Lett. 2020 Jul 17;125(3):033603. doi: 10.1103/PhysRevLett.125.033603.
We demonstrate a non-Hermitian topological effect that is characterized by having complex eigenvalues only in the edge states of a topological material, despite the fact that the material is completely uniform. Such an effect can be constructed in any topological structure formed by two gapped subsystems, e.g., a quantum spin-Hall system, with a suitable non-Hermitian coupling between the spins. The resulting complex-eigenvalued edge state is robust against defects due to the topological protection. In photonics, such an effect can be used for the implementation of topological lasers, in which a uniform pumping provides gain only in the edge lasing state. Furthermore, such a topological lasing model is reciprocal and is thus compatible with standard photonic platforms.
我们展示了一种非厄米拓扑效应，其特征在于，尽管材料完全均匀，但仅在拓扑材料的边缘态具有复本征值。这种效应可以在由两个带隙子系统形成的任何拓扑结构中构建，例如量子自旋霍尔系统，在自旋之间具有合适的非厄米耦合。由于拓扑保护，产生的复本征值边缘态对缺陷具有鲁棒性。在光子学中，这种效应可用于实现拓扑激光器，其中均匀泵浦仅在边缘激射态提供增益。此外，这种拓扑激射模型是互易的，因此与标准光子平台兼容。
