Four-photon entanglement from two-crystal geometry
Yongmin Li, Takayoshi Kobayashi · Physical Review A · 2004
In this paper, a four-photon entangled state obtained directly from the down-conversion of a two-crystal geometry is analyzed. These two identically cut type-I crystals are oriented with their optic axes aligned in perpendicular planes. The applications of this kind of four-photon entangled state are also discussed.