  We have constructed a complete quantum theory for an optical process of
excitons with nonlocal susceptibility originating from their center-of-mass
motion. This theory provides a practical calculation method for
arbitrary-structured nano-to-macro scale dielectrics where excitons are weakly
confined. We obtain good correspondences with underlying theories,
semiclassical microscopic nonlocal theory, and QED theories for dispersive and
absorptive materials with local susceptibility.
