Meng Yan, Lin Shuxin, Shi Bin-Jie, Wei Bin, Yang Linyun, Yan Bei, Zhu Zhenxiao, Xi Xiang, Wang Yin, Ge Yong, Yuan Shou-Qi, Chen Jingming, Liu Gui-Geng, Sun Hong-Xiang, Chen Hongsheng, Yang Yihao, Gao Zhen
Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Research Center of Fluid Machinery Engineering and Technology, School of Physics and Electronics Engineering, Jiangsu University, Zhenjiang 212013, China.
Phys Rev Lett. 2023 Jan 13;130(2):026101. doi: 10.1103/PhysRevLett.130.026101.
For the classification of topological phases of matter, an important consideration is whether a system is spinless or spinful, as these two classes have distinct symmetry algebra that gives rise to fundamentally different topological phases. However, only recently has it been realized theoretically that in the presence of gauge symmetry, the algebraic structure of symmetries can be projectively represented, which possibly enables the switch between spinless and spinful topological phases. Here, we report the experimental demonstration of this idea by realizing spinful topological phases in "spinless" acoustic crystals with projective space-time inversion symmetry. In particular, we realize a one-dimensional topologically gapped phase characterized by a 2Z winding number, which features double-degenerate bands in the entire Brillouin zone and two pairs of degenerate topological boundary modes. Our Letter thus overcomes a fundamental constraint on topological phases by spin classes.
对于物质拓扑相的分类，一个重要的考量是系统是否无自旋或有自旋，因为这两类具有不同的对称代数，会产生根本不同的拓扑相。然而，直到最近才从理论上认识到，在规范对称性存在的情况下，对称性的代数结构可以用射影表示，这可能使得无自旋和有自旋拓扑相之间能够实现转换。在此，我们通过在具有射影时空反演对称性的“无自旋”声学晶体中实现有自旋拓扑相，报告了这一想法的实验证明。特别地，我们实现了一个以2Z缠绕数为特征的一维拓扑带隙相，其在整个布里渊区具有双重简并能带以及两对简并的拓扑边界模式。因此，我们的论文克服了自旋类别对拓扑相的一个基本限制。
