MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Applied Physics Institute and School of Physics, Nankai University, Tianjin 300457, China.
Department of Physics, University of Crete, Heraklion 71003, Greece.
Science. 2021 Apr 2;372(6537):72-76. doi: 10.1126/science.abf6873.
Topology, parity-time (PT) symmetry, and nonlinearity are at the origin of many fundamental phenomena in complex systems across the natural sciences, but their mutual interplay remains unexplored. We established a nonlinear non-Hermitian topological platform for active tuning of PT symmetry and topological states. We found that the loss in a topological defect potential in a non-Hermitian photonic lattice can be tuned solely by nonlinearity, enabling the transition between PT-symmetric and non-PT-symmetric regimes and the maneuvering of topological zero modes. The interaction between two apparently antagonistic effects is revealed: the sensitivity close to exceptional points and the robustness of non-Hermitian topological states. Our scheme using single-channel control of global PT symmetry and topology via local nonlinearity may provide opportunities for unconventional light manipulation and device applications.
拓扑、宇称时间（PT）对称和非线性是自然科学中许多复杂系统基本现象的起源，但它们之间的相互作用仍未得到探索。我们建立了一个非线性非厄米拓扑平台，用于主动调谐 PT 对称和拓扑态。我们发现，非厄米光子晶格中拓扑缺陷势的损耗可以仅通过非线性来调谐，从而实现 PT 对称和非 PT 对称态之间的转变以及拓扑零模的操纵。揭示了两个明显对立效应之间的相互作用：接近异常点的灵敏度和非厄米拓扑态的鲁棒性。我们的方案通过局部非线性对全局 PT 对称和拓扑进行单通道控制，为非常规的光操控和器件应用提供了机会。
