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THU: Thursday Contributed Sessions

THU 7: Entanglement and Complexity: Contributed Session to Symposium II

THU 7.6: Talk

Thursday, September 11, 2025, 15:30–15:45, ZHG008

Hamiltonian many-body model for strong vibrational coupling — •Mathis Noell, Jakob Kullmann, and Carsten Henkel — Universität Potsdam, Institut für Physik und Astronomie, Germany

Molecular vibrations may be strongly coupled to infrared micro cavities, and controversial results have been reported regarding changes in chemical reactions in and out of resonance. We study a simple many-body Hamiltonian that permits to retrieve strong-coupling conditions without recourse to damping. The cavity modes are represented as a dense continuum in an obvious extension of the Tavis-Cummings model. Depending on the scaling of the coupling constants (molecular oscillator strength) with the number of cavity modes and molecules, we find different regimes: the spectrum changes from a collective polariton mode to a photonic band with an anti-crossing. In between these limits, multiple scattering seems to generate spatially complex field patterns. We also consider an interaction including anti-rotating terms and estimate the energy shift of the collective ground state. This bridges polariton and Casimir physics.

Keywords: strong coupling; infrared spectroscopy; collective polaritons; dark states