Page TitleCoherent Light-Matter Interactions in Van der Waals Materials: From Perfect Absorption to Topological Phases

Van der Waals materials combine strong Coulomb and light–matter interactions with the freedom to stack, twist and integrate them into photonic structures. They enable coherent light–matter interaction in regimes difficult to reach in bulk materials.

In this talk, I will discuss these capabilities across distinct regimes of increasingly-strong light-matter couplings. First, even without a cavity, a single monolayer exhibits a collective Lamb shift and perfect absorption. Second, a weakly coupled cavity amplifies Floquet driving, producing effective magnetic fields above 200 T and enabling ultrafast, non-reciprocal control of light. Third, in the strong-coupling regime, these materials form unconventional exciton-polaritons, with nonlinearity enhanced by moiré superlattices and, in the layered magnet CrSBr, strongly coupled atomic and photonic anisotropies. Finally, I will show how Coulomb interactions with a gate-controlled Fermi sea, strong light–matter coupling and 2D photonic crystals together produce Chern polaritons with gate-invertible topology and a gap 40-times larger than the previous record. These results open a route to topological phases of interacting light and matter.