Quantum entanglement swapping with spontaneous parametric down-conversion

Two remote. parties that have never interacted each other can be entangled through entanglement swapping operation done by a third party. Currently existing entanglement swapping experiments are done probabilistically by postselection, i.e., once a successful swapping is verified, the resultant entanglement is destructed. We propose a simple nonpostselection scheme to demonstrate the high-quality quantum entanglement swapping with the spontaneous parametric down-conversion process. Our scheme only requires the normal photon detectors which only distinguish the vacuum and nonvacuum Fock states.