Multipartite entanglement purification with quantum nondemolition detectors Y. B. Sheng, F. G. Deng, B. K. Zhao, T. J. Wang and H. Y. Zhou Eur. Phys. J. D, 55 1 (2009) 235-242 Published online: 22 August 2009 DOI: 10.1140/epjd/e2009-00237-y