We propose a nonlocal entanglement concentration protocol (ECP) for -photon systems in a partially entangled state, resorting to some ancillary single photons and the parity-check measurement based on cross-Kerr nonlinearity. One party in quantum communication first performs a parity-check measurement on her photon in an -photon system and an ancillary photon, and then she picks up the even-parity instance for obtaining the standard state. When she obtains an odd-parity instance, the system is in a less-entanglement state, and it is the resource in the next round of entanglement concentration. By iterating the entanglement concentration process several times, the present ECP has a total success probability approaching the limit in theory. The present ECP has the advantage of a high success probability. Moreover, the present ECP requires only the -photon system itself and some ancillary single photons, not two copies of the systems, which decreases the difficulty of its implementation greatly in experiment. It may have good applications in quantum communication in the future.
© 2012 Optical Society of America
(270.0270) Quantum optics : Quantum optics
(270.5585) Quantum optics : Quantum information and processing
Original Manuscript: March 19, 2012
Manuscript Accepted: March 28, 2012
Published: May 23, 2012
Fang-Fang Du, Tao Li, Bao-Cang Ren, Hai-Rui Wei, and Fu-Guo Deng, "Single-photon-assisted entanglement concentration of a multiphoton system in a partially entangled W state with weak cross-Kerr nonlinearity," J. Opt. Soc. Am. B 29, 1399-1405 (2012)