Hong-Ou-Mandel Two-Photon Interference

The Hong–Ou–Mandel effect is one of the cleanest demonstrations that photons are not classical particles: send two indistinguishable single photons into opposite input ports of a 50/50 beamsplitter and quantum interference between the "both reflect" and "both transmit" amplitudes cancels the coincidence outcome entirely, forcing both photons out of the same port together. This simulator renders the beamsplitter, the two photon paths, and two single-photon detectors in 3D, fires a continuous stream of simulated photon pairs whose fate is sampled from the real coincidence-probability formula, and plots the resulting Hong–Ou–Mandel dip live as you sweep the photons' relative arrival delay, spectral coherence time, and the beamsplitter's reflectivity.