Polarization correlation in the two-photon decay of atomic hydrogen: nonlocality versus entanglement T. Radtke, A. Surzhykov and S. Fritzsche Eur. Phys. J. D, 49 1 (2008) 7-12 Published online: 11 July 2008 DOI: 10.1140/epjd/e2008-00132-1