Mode Distinguishability in Multi-photon Interference

The Hong-Ou-Mandel (HOM) effect is a quintessential process in various quantum information technologies and quantum optics applications. In this work, we investigate multi-photon interference, developing a model for the simultaneous characterization of polarization and spectro-temporal mode mismatch on the coincidence probabilities including the effects of realistic imperfections of devices used in HOM experiments. We also study the coincidence probability for coherent states as a function of source intensity, as well as spectro-temporal and polarization mismatch of the incident beams. We apply our model to the case of multi-photon interference from independent sources and analyze the consequences of mode mismatch in various instances that occur in quantum networking including entanglement swapping, quantum key distribution, quantum sensing, quantum optical classification, and photonic quantum computing.