论文标题
高阶拓扑厅的声音效果
Higher-order topological spin Hall effect of sound
论文作者
论文摘要
从理论上讲，我们提出了一个可重构的二维（2D）六边形声音晶体，其高阶拓扑受到六倍的$ C_6 $，旋转对称性的保护。可以通过旋转每个单位细胞中的三角散射器来控制声带隙和带拓扑。在非平凡阶段，声音晶体以高阶的方式实现了拓扑旋转霍尔的效果：（i）散装带隙中出现的边缘状态表现出部分旋转摩托杆锁定，并且由于边缘处的空间对称性降低而被散布。 （ii）另一方面，间隙边缘状态稳定了边缘隙中出现的拓扑角状态。部分自旋摩肌锁定表现为边缘状态的伪旋转偏振，远离时间反转的动量，在那里，伪源性通过声学轨道角动量模仿。我们使用基于声学的对称性表示的角拓扑指数揭示了潜在的拓扑机制。
We propose theoretically a reconfigurable two-dimensional (2D) hexagonal sonic crystal with higher-order topology protected by the six-fold, $C_6$, rotation symmetry. The acoustic band gap and band topology can be controlled by rotating the triangular scatterers in each unit-cell. In the nontrivial phase, the sonic crystal realizes the topological spin Hall effect in a higher-order fashion: (i) The edge states emerging in the bulk band gap exhibits partial spin-momentum locking and are gapped due to the reduced spatial symmetry at the edges. (ii) The gapped edge states, on the other hand, stabilize the topological corner states emerging in the edge band gap. The partial spin-momentum locking is manifested as pseudo-spin-polarization of edge states away from the time-reversal invariant momenta, where the pseudospin is emulated by the acoustic orbital angular momentum. We reveal the underlying topological mechanism using a corner topological index based on the symmetry representation of the acoustic Bloch bands.
