Dresden 2026 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

TT: Fachverband Tiefe Temperaturen

TT 74: Topological Insulators

TT 74.9: Talk

Thursday, March 12, 2026, 11:45–12:00, CHE/0091

Topological invariants for the SSH model coupled to a single mode cavity — •Anna Ritz-Zwilling and Olesia Dmytruk — CPHT, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France

Coupling electronic systems to cavity photons offers a promising route to probe and control material properties through light-matter interactions. In particular, coupling to light might enable manipulation of topological phases of matter, which have gained significant attention due to their potential applications in quantum technologies. Yet, while the topological classification of non-interacting fermionic systems is well understood within the tenfold way, much less is known about how to identify topological protection when photonic operators enter the problem. In this work, we consider the Su-Schrieffer-Heeger (SSH) model as a paradigmatic one-dimensional topological insulator. In its topological phase, the SSH model exhibits zero-energy edge states protected by chiral symmetry. When the system is coupled to a cavity, however, it remains unclear whether chiral symmetry and topological protection survive. To address this question, we use a recently developed high-frequency expansion of the light-matter Hamiltonian, which traces out photonic degrees of freedom and yields an effective fermionic model. Light-matter coupling then manifests as additional interaction terms, allowing us to apply known results for interacting topological insulators. We discuss the symmetries of this effective model, compute observables such as the electronic polarization as potential topological invariants and analyze the fate of edge states.

Keywords: interacting topological insulators; cavity coupling; polarization; winding number