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

The famous Hong-Ou-Mandel two-photon coincidence-visibility dip (TPCVD), which accepts one photon into each port of a balanced beam splitter and yields an equal superposition of a biphoton from one output port and vacuum from the other port, has numerous applications in photon-source characterization and to quantum metrology and quantum computing.
Exceeding 50% two-photon-coincidence visibility is widely believed to signify quantumness. In this talk, we show theoretically that classical light can yield a 100% TPCVD for controlled randomly chosen relative phase between the two beam-splitter input beams and experimentally demonstrate a 99.635 +/- 0.002% TPCVD with classical microwave fields.
We show quantumness emerges via complementarity for the biphoton by adding a second beam splitter to complete an interferometer thereby testing whether the biphoton interferes with itself: Our quantum case shows the proper complementarity trade-off whereas classical microwaves fail.