论文标题
声学晶体中的高阶拓扑
Higher-order topological semimetal in acoustic crystals
论文作者
论文摘要
高阶拓扑绝缘子的概念使材料具有拓扑状态，超出了一阶。特别是，三维（3D）高阶拓扑绝缘子可以托管受拓扑保护的1D铰链状态，称为二阶拓扑绝缘子或0D角状态，称为第三阶拓扑绝缘子。同样，如果3D高阶拓扑半学在1D铰链上托管状态，则可以设想它。在这里，我们报告了在3D打印的声学晶体中实现二阶拓扑Weyl半学的，该晶体具有3D动量空间中的Weyl点，在铰链上的表面上的2d Fermi Arc状态在表面和1D无间隙状态上。像弧形表面状态一样，铰链状态也连接了Weyl点的投影。我们的实验结果证明了高阶拓扑半学的存在，这可能为创新的声学设备铺平了道路。
The notion of higher-order topological insulators has endowed materials with topological states beyond the first order. Particularly, a three-dimensional (3D) higher-order topological insulator can host topologically protected 1D hinge states, referred to as the second-order topological insulator, or 0D corner states, referred to as the third-order topological insulator. Similarly, a 3D higher-order topological semimetal can be envisaged if it hosts states on the 1D hinges. Here we report the realization of a second-order topological Weyl semimetal in a 3D-printed acoustic crystal, which possesses Weyl points in 3D momentum space, 2D Fermi arc states on surfaces and 1D gapless states on hinges. Like the arc surface states, the hinge states also connect the projections of the Weyl points. Our experimental results evidence the existence of the higher-order topological semimetal, which may pave the way towards innovative acoustic devices.
