论文标题
Wannier-type光子高阶拓扑角状态仅由增益和损失引起
Wannier-type photonic higher-order topological corner states induced solely by gain and loss
论文作者
论文摘要
光子晶体提供了一个可控的平台，可以检查开放系统中令人兴奋的新拓扑状态。在这项工作中，我们在光子石墨烯中揭示了具有镜面模式增益和损失的光子拓扑角状态。这种非平凡的Wannier型高阶拓扑阶段是通过仅调整现场增益/损失强度来实现的，这会导致在时间反向对称点上歼灭两个山谷狄拉克锥，因为增益和损失会改变相邻站点之间的有效隧道。我们发现，对称性保护的光子角模式表现出纯粹虚构的能量，并且说明了震颤中心作为拓扑不变的作用。对于实验考虑，我们还检查了域壁附近的拓扑界面状态。我们的工作介绍了一个有趣的平台，用于非热诱导的光子高阶拓扑造型器，使用当前的实验技术，可以很容易地访问。
Photonic crystals have provided a controllable platform to examine excitingly new topological states in open systems. In this work, we reveal photonic topological corner states in a photonic graphene with mirror-symmetrically patterned gain and loss. Such a nontrivial Wannier-type higher-order topological phase is achieved through solely tuning on-site gain/loss strengths, which leads to annihilation of the two valley Dirac cones at a time-reversal-symmetric point, as the gain and loss change the effective tunneling between adjacent sites. We find that the symmetry-protected photonic corner modes exhibit purely imaginary energies and the role of the Wannier center as the topological invariant is illustrated. For experimental considerations, we also examine the topological interface states near a domain wall. Our work introduces an interesting platform for non-Hermiticity-induced photonic higher-order topological insulators, which, with current experimental technologies, can be readily accessed.
