Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 9: Open Quantum Systems and Spin-Boson Systems I

Q 9.2: Talk

Monday, March 2, 2026, 17:15–17:30, P 4

Non-classical features in vibrational states under electronic strong coupling — •Réka Schwengelbeck, Maxence Pandini, Ruben Daraban, and Johannes Schachenmayer — CESQ/ISIS (UMR 7006), CNRS and Université de Strasbourg, 67000 Strasbourg, France

We analyze vibrational dynamics in a toy-model setup for polaritonic chemistry under collective electronic strong coupling with many molecules. In a Holstein-Tavis-Cummings model, incoherently excited by a photon, we show that disorder leads to non-Gaussian states of vibrational modes on short time scales at the single-molecule level. Using exact matrix product state simulations, we demonstrate that this effect can remain robust for larger molecule numbers and cannot be effectively described with thermal states. Furthermore, we compare simulations of the exact quantum dynamics with semi-classical approximations. We find that the Ehrenfest approximation can reproduce only ensemble-averaged observables in the thermodynamic limit. Simulations in the truncated Wigner approximation can qualitatively produce some asymmetric features of vibrational Wigner functions, but fail to capture the non-Gaussian effects quantitatively. Our work highlights the importance of disorder and genuine quantum effects in understanding cavity-modified nuclear dynamics in polaritonic chemistry at the microscopic level.

Keywords: Strong light–matter coupling; Disordered Holstein–Tavis–Cummings model; Polaritonic chemistry; Matrix product states (MPS); Vibrational quantum dynamics