The topological edge state (TES) may emerge at the interface between acoustic crystals with distinct topological properties. It supports robust wave phenomena against geometry imperfections. By imposing holistic onsite gains and losses in PT symmetric Su-Schrieffer-Heeger lattices, zero mode can be obtained from the convergence of two splitting TES modes induced by adjacent coupling. However, the nonlocal non-Hermiticity requires exorbitant configuration on each atom, resulting in complex systems. Here, we demonstrate the effect of local non-Hermitian modulation to the coupled TESs, utilizing passive acoustic crystals with sandwiched arrangements. Local non-Hermiticity is introduced at the position of one of the TESs to manipulate the splitting TESs. By suitably adjusting the non-Hermitian strength, the splitting TESs experience the coalescence process along with the asymmetric reflection and absorption near and beyond the exceptional point. Due to the topological essentials, the emergence of the exceptional point also can be proved to be robust to the geometrical disorders. Our results reveal that coupled TESs can be modulated by local non-Hermiticity to realize the extraordinary scattering phenomena, which may inspire more acoustic functional devices based on the topological or non-Hermitian characteristics.

中文翻译：

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声晶体中具有局部非Hermitian调制的拓扑保护例外点

拓扑边缘状态（TES）可能出现在具有不同拓扑特性的声晶体之间的界面上。它支持针对几何缺陷的鲁棒波现象。通过在PT中施加整体现场收益和损失对称的Su-Schrieffer-Heeger晶格，可以通过相邻耦合引起的两个分裂TES模式的收敛获得零模式。但是，非局部非赫米性要求每个原子上的构型过高，从而导致系统复杂。在这里，我们演示了使用夹层结构的无源声晶体对耦合TES进行局部非Hermitian调制的效果。在一个TES的位置引入局部非赫米性，以操纵分裂的TES。通过适当地调整非埃尔米特强度，分裂的TES会经历合并过程以及在异常点附近和超出异常点的不对称反射和吸收。由于拓扑学的要点，特殊点的出现也可以证明对几何异常具有鲁棒性。