Floquet规范转变诱导拓扑π模产生的理论分析

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 Origin of π Interface Modes Induced by Floquet Gauge Transition

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 topological π mode 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 topological π mode induced by the gauge field transition are discussed. The Hamiltonian of two Floquet systems with different gauges has opposite π gap 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.