Floquet规范转变诱导拓扑π模产生的理论分析

Topological Origin ofπInterface Modes Induced by Floquet Gauge Transition

拓扑绝缘体是一类内部绝缘而在表面可以导电的物态,其倒空间的能带具有非平庸的拓扑特性,而在其实空间的边界上具有可以单向传播的边界态。这种拓扑界面态出现往往依赖于界面处的拓扑相变。而最近有研究在一类Floquet的拓扑体系中实验观测到一种规范场相变诱导产生的拓扑π模,这种拓扑态的产生可能不依赖于拓扑相变。本文对于这种规范场诱导的拓扑π模的产生机理做出了理论解释。两个Floquet规范相反的体系的哈密顿量由于规范相变而具有相反的π能隙质量项,类似于Jackiw-Rebbi模型,从而导致拓扑界面态的出现。本文的研究为规范场相变诱导拓扑模式的产生提供了理论基础,并加深了人们对于Floquet规范场的理解。

Topological insulator is a kind of phase of matter that is internally insulated and can conduct electricity on the surface.The energy band of a topological insulator has non-trivial topological characteristics,which supports a boundary state that can propagate in one direction.The appearance of topological states usually depends on the topological phase transition at the interface or boundary.Recently,a new topologicalπmode induced by gauge transitions has been successfully observed experimentally in Floquet systems,despite the same topological order across the whole lattices.In this paper,the origin of the topologicalπmode induced by the gauge field transition are discussed.The Hamiltonian of two Floquet systems with different gauges has oppositeπgap mass terms due to gauge transition,thus leads to the emergence of interface states,which is similar to the Jackiw-Rebbi model.The research of this paper provides a theoretical basis for the generation of topological states from gauge transitions,and deepen the understanding of the Floquet gauge.