Quantization of Electromagnetic Fields in Inhomogeneous and Anisotropic Zero-Index Nonlinear Media

We present a rigorous microscopic framework for quantizing electromagnetic fields in highly nonlinear zero-index materials that may be inhomogeneous, anisotropic, lossy, and dispersive. Our approach utilizes a non-perturbative formalism, where the medium is modeled as an ensemble of effective two-level systems exhibiting a large third-order susceptibility. Our findings pave the way towards practical applications in quantum photonics, such as single-photon nondemolition detection, by leveraging the strong nonlinearities intrinsic to zero-index materials.