Non-linear regime of atomic arrays at low drive intensity: controlled generation of multiple subradiant excitations via a multi-photon resonance (2409.01386v2)

Abstract: Atomic arrays have emerged as an interesting light-matter platform displaying strong and controllable collective effects. In subwavelength regimes, they are characterized by a manifold of subradiant eigenstates, which can host rich quantum many-body physics and might be useful for applications. Nevertheless, their controlled excitation by a weak coherent drive is prevented by their subradiant nature. While this is true at a linear level, and although the weak-drive regime has been often described using linear theories, we point out that this regime is instead strongly non-linear for regular arrays. Using a dynamical mean-field theory (DMFT) approach, we show that by driving weakly a non-linear two-particle resonance, a steady-state with a controlled population of subradiant modes can be obtained. This features a non-zero density of interacting subradiant excitations, displaying multi-mode squeezing correlations and long-range correlations that survive many-body heating effects, even at non-zero drive intensities.