探究弦球链系统的拓扑不变量  

Studies on topological invariants of a string-ball chain

作　　者：林织星 王志元 杨天骅 LIN Zhi-xing;WANG Zhi-yuan;YANG Tian-hua(School of Physics,Peking University,Beijing 100871,China)

机构地区：[1]北京大学物理学院,北京100871

出　　处：《大学物理》2022年第3期51-55,共5页College Physics

摘　　要：周期性弦球链体系作为典型的声子晶体体系,其能带结构已得到了广泛而深入的研究.在实际观测体系能谱的过程中,会探测到一类特殊的能量本征态——边缘态(能量处在带隙间,且波函数局域在体系边缘的态),同时观察到其存在具有一定的鲁棒性.由于实验上观测到的弦球链边缘态的性质与电子体系中拓扑绝缘体的边缘态性质的相似性,可以利用同一套能带拓扑的语言研究弦球链体系.本文通过数值计算能带的拓扑不变量,揭示了弦球链体系非平庸的拓扑性质,从而证明了实验上探测到的边缘态是拓扑保护的边缘态.基于数值计算的结果,讨论了体系的拓扑相变与边缘态的输运性质。As a representative acoustic system,band structure of a periodical string-ball chain has been widely studied.In spectrum measurement,it’s noteworthy that a novel,robust class of eigenstates(edge states),whose energy lies in the band gap and wave function locates at the edge of the system,have been detected.In this paper,the resemblance between the experiment-observed edge states and ones in topological insulator enabled to develop an analogous theory of topological acoustics to study string-ball system.Numerical simulation of topology invariants demonstrates non-trivial topological properties of the experiment system,proving that the observed edge states are topological-protected edge states;Based on numerical results,a brief discussion is given on topological phase transition and transport properties of edge states.

关 键 词：边缘态 拓扑不变量 拓扑相变 输运性质 

分 类 号：O329[理学—一般力学与力学基础]