Linear response theory for cavity QED materials at arbitrary light-matter coupling strengths
Juan Román-Roche, Álvaro Gómez-León, Fernando M. Luis, David Zueco · Physical review. B./Physical review. B · 2025
The authors develop a linear response theory for materials collectively coupled to a cavity that is valid in all regimes of light-matter coupling, including symmetry-broken phases. The response functions for the cavity and the material are obtained in terms of the respective bare responses. The theory is formulated for a general model which encompasses most of the systems typically considered in the field of cavity QED materials. It is then applied to several specific models.