Patent ID: 7570419

Claim:
A quantum entangled photon pair producing device comprising superposition state generating means and light-guide means, wherein: the superposition state generating means generates a superposition state of photon pairs entering the light guide means from a same direction through an N (N≧2) number of different incident optical paths which are parallel to each other, the photon pair being composed of photons having different polarization directions; and the light-guide means separates each of the photon pairs entering from a same direction through the N number of incident optical paths into a photon having a first polarization direction and a photon having a second polarization direction, and guides the photon entering through an i-th (1≦i≦N) entrance optical path and having the first polarization direction and the photon entering through an (N−i+1)-th incident optical path and having the second polarization direction to the i-th exit optical path through optical paths having a same optical path length.