Photonic Entanglement Based on Nonlinear Metamaterials

Abstract Metamaterials consisting of deep subwavelength artificial “atoms” have been utilized to demonstrate a series of novel phenomena such as negative refraction and epsilon‐near‐zero. In recent times, metamaterials have been developed as an up‐and‐coming platform for quantum optics. Here the generation and modulation of photonic entanglement are investigated based on the parametric down conversion processes in metamaterials with considerable optical nonlinearity. Through flexible nanostructure design, the nonlinear photonic interaction in the metamaterial system can be effectively tailored. The distributions of optical parameters of the system are inhomogeneous, based on which the spatial properties of the generated photonic state can be steered as desired. The theoretical framework to describe this system is established based on the nonlinear Huygens–Fresnel principle, and a differential approach is utilized to deal with the intrinsic loss of the system. The generation of orbital angular momentum entangled states is actually considered as an illustration. This platform could be valuable for the practical applications of quantum information processing.