title: Experimental realization of entanglement concentration and a quantum repeater.
abstract: We report an experimental realization of entanglement concentration using two polarization-entangled photon pairs produced by pulsed parametric down-conversion. In the meantime, our setup also provides a proof-in-principle demonstration of a quantum repeater. The quality of our procedure is verified by observing a violation of Bell's inequality by more than 5 standard deviations. The high experimental accuracy achieved in the experiment implies that the requirement of tolerable error rate in multistage realization of quantum repeaters can be fulfilled, hence providing a useful toolbox for quantum communication over large distances.
authors.affiliation: Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230027, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhao
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Yu-Ao
authors.initials: YA
authors.lastname: Chen
authors.forename: An-Ning
authors.initials: AN
authors.lastname: Zhang
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Pan