Distinguishing four photons in an entangled state from two independent pairs of photons
Z. Y. Ou · Physical Review A · 2005
We analyze in a multimode model a recent scheme [Tsujino et al., Phys. Rev. Lett. 92, 153602 (2004)] to distinguish entangled four-photon polarization state from two independent polarization entangled pairs of photons in a single type-II parametric down-conversion process. The fraction of the four-photon entangled state among the two detected photon pairs is found to be related to a quantity that is responsible for the temporal mode match between the photon pairs. A comparison with the single mode models is discussed.