Teleportation experiment
In the experiment a pulse from a mode-locked Ti:sapphire laser (not shown) is frequency doubled, and the resulting UV pulse is used to create the entangled pair of "ancillary" photons in a nonlinear crystal. The UV pulse is then reflected back through the crystal to produce a second pair of photons: one is used as the teleportee while the other acts as a "trigger". Polarizers are used to prepare the teleportee photon in a well defined state, while various filters ensure that no path information is available about Alice's photons. Coincident photons detections at f1 and f2 project the photons onto a |Yñ state (in which they have different polarizations). And since Alice's ancillary and Bob's photon are also entangled, this detection collapses Bob's photon into an identical replica of the original.