Observation of correlated-photon statistics using a single detector

We report an experimental observation of correlated-photon statistics using a single detector. The usual coincidence dip in a two-photon polarization interferometer is accompanied by a dip in single-photon detection rates. Surprisingly, a dip in the singles rate is also observed when the interferometer is aligned for a coincidence peak, or anti-dip. This effect is explained by taking into account all possible photon number states that reach the detector, rather than considering just the state post-selected by the coincidence measurement.