Experimental Study of Hong–Ou–Mandel Interference Using Independent Phase Randomized Weak Coherent States...

Hong–Ou–Mandel interferometers are valuable tools in many Quantum Information and Quantum Optics applications that require photon indistinguishability. The theoretical limit for the Hong–Ou–Mandel visibility is 0.5 for indistinguishable weak coherent photon states, but several device imperfections may hinder achieving this value experimentally. In this work, we examine the dependence of the interference visibility on various factors, including 1) detector side imperfections due to after-pulses, 2) mismatches in the intensities and states of polarization of the input signals, and 3) the overall intensity of the input signals. We model all imperfections and show that theoretical modeling is in good agreement with the experimental results.