Controlling quantum matter via strong light-matter coupling in cavities

by Dr Frieder Lindel (ETH Zurich)

Wednesday 19 Nov 2025, 15:00 → 16:00 Europe/Zurich

OVGA/200

External classical radiation can be used to control chemical processes and the properties of quantum materials. An alternative method of controlling many-body dynamics involves replacing the external radiation with the quantized modes of a dark cavity. In my talk, I will first introduce a quantised embedding approach that enables to treat the collective coupling of molecular many-body systems to a realistic cavity while maintaining the rigour of ab initio quantum chemistry for the molecular structure [1]. This approach fully incorporates the quantum fluctuations of the polaritonic field, yet remains more intuitive than complex embedding approaches such as dynamical mean-field theory, and it can be linked to simplified light-matter coupling models, such as the Tavis-Cummings model. Secondly, we will discuss Casimir control [2] as a new mechanism for cavity control of electronic nematic order in Fermi liquids, where different electronic order orientations are often energetically degenerate. We will find that the zero-point energy of the electromagnetic continuum, the Casimir energy, depends on the properties of the material system. This can be exploited to stabilize particular orientations of the nematic order. The experimental feasibility will be illustrated using the example of a quantum Hall stripe system [3].

[1] Lindel et al., Quantized embedding approaches for collective strong coupling— Connecting ab initio and macroscopic QED to simple models in polaritonics, J. Chem. Phys. 161, 154111 (2024).

[2] O. Carlsson, S. Chattopadhyay, J. B. Curtis, F. Lindel, L. Graziotto, J. Faist, E. Demler, Casimir Stabilization of Fluctuating Electronic Nematic Order, preprint at arXiv:2510.05088 (2025).

[3] L. Graziotto et al., Cavity QED Control of Quantum Hall Stripes, preprint at arXiv:2502.15490 (2025).