Photon correlations in multi-mode waveguides
We consider the propagation of classical and non-classical light in multi-mode optical waveguides. We focus on the evolution of the few-photon correlation functions, which, much like the light-intensity distribution in such systems, evolve in a periodic manner, culminating in the 'revival' of the initial correlation pattern at the end of each period. It is found that when the input state possesses non trivial symmetries, the correlation revival period can be longer than that of the intensity, and thus the same intensity pattern can display different correlation patterns. We experimentally demonstrate this effect for classical, pseudo-thermal light, and compare the results with the predictions for non-classical, quantum light.