Ao Yutian, Hu Xiaoyong, You Yilong, Lu Cuicui, Fu Yulan, Wang Xingyuan, Gong Qihuang
State Key Laboratory for Mesoscopic Physics & Department of Physics, Collaborative Innovation Center of Quantum Matter & Frontiers Science Center for Nano-optoelectronics, Beijing Academy of Quantum Information Sciences, Peking University, Beijing 100871, China.
Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China.
Phys Rev Lett. 2020 Jul 3;125(1):013902. doi: 10.1103/PhysRevLett.125.013902.
In a two-dimensional non-Hermitian topological photonic system, the physics of topological states is complicated, which brings great challenges for clarifying the topological phase transitions and achieving precise active control. Here, we prove the topological phase transition exists in a two-dimensional parity-time-symmetric coupled-resonator optical waveguide system. We reveal the inherent condition of the appearance of topological phase transition, which is described by the analytical algebraic relation of coupling strength and the quantity of gain-loss. In this framework, the system can be switched between the topological and trivial states by pumping the site rings. This work provides a new degree of freedom to control topological states and offers a scheme for studying non-Hermitian topological photonics.
在二维非厄米拓扑光子系统中，拓扑态的物理性质较为复杂，这给阐明拓扑相变以及实现精确的主动控制带来了巨大挑战。在此，我们证明了在二维宇称-时间对称耦合谐振器光波导系统中存在拓扑相变。我们揭示了拓扑相变出现的内在条件，该条件由耦合强度与增益-损耗量的解析代数关系描述。在此框架下，通过对位点环进行抽运，系统可在拓扑态和平凡态之间切换。这项工作为控制拓扑态提供了一个新的自由度，并为研究非厄米拓扑光子学提供了一种方案。
