论文标题
在定期淬火的格子中
Non-Hermitian Floquet second order topological insulators in periodically quenched lattices
论文作者
论文摘要
高阶拓扑阶段的特征是被局部位于系统拐角处或铰链的保护状态。通过将时间周期性的淬灭施加到具有平衡增益和损失的二维晶格上，我们获得了丰富的多种非富尔克斯弗拉奎特二级拓扑绝缘阶段。每个阶段的特征都以一对整数拓扑不变性，可预测零和$π$ quasienergies的浮点角模式的数量。我们建立了模型的拓扑相图，并找到一系列非热性诱导的二阶拓扑阶段之间的过渡。我们将平均手性位移进一步概括为二维非温和系统，并使用它动态地提取我们模型的拓扑不变性。因此，这项工作将高阶拓扑物质的研究扩展到了更通用的非平衡环境，在这种情况下，浮雕工程和非热性之间的相互作用产生了引人入胜的新阶段。
Higher-order topological phases are characterized by protected states localized at the corners or hinges of the system. By applying time-periodic quenches to a two-dimensional lattice with balanced gain and loss, we obtain a rich variety of non-Hermitian Floquet second order topological insulating phases. Each of the phases is characterized by a pair of integer topological invariants, which predict the numbers of Floquet corner modes at zero and $π$ quasienergies. We establish the topological phase diagram of the model, and find a series of non-Hermiticity induced transitions between different Floquet second order topological phases. We further generalize the mean chiral displacement to two-dimensional non-Hermitian systems, and use it to extract the topological invariants of our model dynamically. This work thus extend the study of higher-order topological matter to more generic nonequilibrium settings, in which the interplay between Floquet engineering and non-Hermiticity yields fascinating new phases.
