Near-100% two-photon-like coincidence-visibility dip with classical light and the role of complementarity

The Hong-Ou-Mandel effect is considered a signature of the quantumness of light, as the dip in coincidence probability using semiclassical theories has an upper bound of 50%. Here we show, theoretically and experimentally, that, with proper phase control of the signals, classical pulses can mimic a Hong-Ou-Mandel-like dip. We demonstrate a dip of (99.635±0.002)% with classical microwave fields. Quantumness manifests in wave-particle complementarity of the two-photon state. We construct quantum and classical interferometers for the complementarity test and show that while the two-photon state shows wave-particle complementarity the classical pulses do not.