Cavity-induced topological edge and corner states

TL;DR

This paper explores how photon coupling in a cavity can induce and modify topological edge and corner states in certain quantum models, revealing new cavity-induced topological phenomena.

Contribution

It demonstrates the emergence of cavity-induced topological edge and corner states in specific quantum lattice models, a novel mechanism for topological state manipulation.

Findings

Photon coupling causes zero-energy edge states to acquire nonzero energy.

Strong photon coupling transforms photon states into topological edge or corner states.

Certain topological states remain unaffected by the cavity, staying at zero energy.

Abstract

We investigate a two-level system with alternating XX coupling in a photon cavity. It is mapped to a free boson model equally coupled to a photon, whose interaction is highly nonlocal. Some intriguing topological phenomena emerge as a function of the photon coupling. The photon energy level anticrosses the zero-energy topological edges at a certain photon coupling, around which the symmetric edge state acquires nonzero energy due to the mixing with the photon. Furthermore, the photon state is transformed into the topological zero-energy edge or corner state when the photon coupling is strong enough. It is a cavity-induced topological edge or corner state. On the other hand, the other topological edge or corner states do not couple with the photon and remains at zero energy even in the presence of the cavity. We analyze a cavity-induced topological edge state in the Su-Schrieffer-Heeger model and a cavity-induced topological corner state in the breathing Kagome model.