This invention relates generally to a method and system for hybrid classical-quantum communication. The method comprises transmitting a single photon having a particular quantum state over a communication medium using a quantum mode set; and transmitting a classical light beam over the same communication medium using a classical mode set, wherein the classical and quantum mode sets comprise non-separable modes in common. The non-separable modes in common may be two degrees of freedom of a single photon or classical light and may thus be spatial modes in one or more indexes, and polarisation. The invention relates also to a system to implement the method accordingly.