Preparation and purification of four-photon Greenberger–Horne–Zeilinger state
Ying-Qiu He, Dong Ding, Feng-Li Yan, Ting Gao · Journal of Physics B Atomic Molecular and Optical Physics · 2015
We present an efficient scheme for the preparing and purifying of the four-photon Greenberger–Horne–Zeilinger (GHZ) state based on linear optics and postselection. First, we describe how to create a four-photon GHZ state in both polarization and spatial degrees of freedom from two pairs. Moreover, in the presence of depolarization noise our scheme is capable of purifying the desired state. In the regime of weak nonlinearity we design an indirect photon number-resolving detection to distinguish two states of the two pairs. At last, a fourfold coincidence detector click indicates the creation of a polarization-entangled four-photon GHZ state.