# Computational Macroscopic QED Framework for Vibrational Polaritons

Athul Sambasivan Universidad de Santiago de Chile

Athul S. Rema (a) and Felipe Herrera (a,b)

(a) Department of Physics, Universidad de Santiago de Chile, Av. Victor Jara 3493, Santiago, Chile

(b) Millennium Institute for Research in Optics, Chile

Near-resonant molecule-field interactions have attracted significant attention in chemical physics and quantum optics [1,2]. We study the quantum dynamics of a molecular vibration coupled to near-field modes of an infrared nanoresonator using macroscopic quantum electrodynamics (QED). Nanophotonic structures vary in geometry and material properties, which makes the calculations of interaction dynamics challenging [3]. We use the electromagnetic Green’s tensor of the nanophotonic structure to construct frequency and position dependent interaction Hamiltonians in macroscopic QED that are used to derive and numerically solve the system of non-Markovian integro-differential equations (IDE) that describe the dynamics of vibrational and photonic degrees of freedom in strong coupling. The material and dipole parameters are encoded in the structure of the kernel function of the IDE. We solve for photonic and vibrational observables for a single non-polar anharmonic vibration in a resonant infrared nanocavity and compare the results with recent phenomenological Markovian models developed for vibrational polaritons [4], to better understand the reach and limitations of reduced Markovian quantum optics models to describe currently available experiments.

[1] F. Herrera and J. Owrutsky, J. Chem. Phys. 152, 100902 (2020).

[2] T. W. Ebbesen, Acc. Chem. Res. 49, 11, 2403–2412, (2016).

[3] J. Feist, A. I. Fernandez-Dominguez, and Francisco J. Garcia-Vidal. Nanophotonics, 10, 477- 489, (2021).

[4] J. Triana, M. Arias, J. Nishida, E. Muller, R. Wilcken, S. C. Johnson, A. Delgado, M. B. Raschke, F. Herrera, Semi-empirical quantum optics for mid-infrared molecular nanophotonics, J. Chem. Phys. 156, 124110, 2022.