Quantum operator for non-paraxial single photon interference

Interference in optics has been described as a result of the superposition of light waves in ordinary space. However, this phenomenological description does not seem to fit non-paraxial single-photon interference in ordinary space due to the corpuscular nature of photons and the fact that only one photon moves in the setup at each time. A quantum interference operator, deduced from the exact (non- paraxial) mathematical model, indicates that the spatial morphology of interference is independent of the presence of photons in the setup and remains unchanged in their absence. This suggests a new interpretation of interference in terms of the photon confinement in geometric states of ordinary space. Here, we discuss the physical and phenomenological implications of this new interpretation.