Quantum nonlinear metasurfaces from dual arrays of ultracold atoms

Abstract

Optical interfaces with subwavelength patterns make it possible to manipulate light waves beyond the typical capabilities of ordinary optical media. Subwavelength arrays of ultracold atoms enable such transformations at very low photon losses. Here, we show how the coupling of light to more than a single atomic array can expand these perspectives into the domain of quantum nonlinear optics. While a single array transmits and reflects light in a highly coherent but largely linear fashion, the combination of two arrays is found to induce strong photon-photon interactions that can convert an incoming classical beam into strongly correlated photonic states. Such quantum metasurfaces open up new possibilities for coherently generating and manipulating nonclassical light, and exploring quantum many-body phenomena in two-dimensional systems of strongly interacting photons.