Multi-photon entangled states from two-crystal geometry parametric down-conversion and their application in quantum teleportation

In this paper, we show that two kinds of W-type entangled states can be generated from a non-degenerate two-crystal geometry parametric down-conversion and they are very useful for quantum teleportation and quantum cloning. We also show that quantum teleportation of unknown one-particle state from a sender to either one of three receivers can be realized probabilistically by using the four-photon entangled state directly from a degenerate two-crystal geometry parametric down-conversion.