Entanglement Persistency of Multiphoton Entangled States
Mohamed Bourennane, Manfred Eibl, Sascha Gaertner, Nikolai Kiesel, Christian Kurtsiefer, Harald Weinfurter · Physical Review Letters · 2006
We experimentally demonstrate the entanglement persistency when losing photons in three- and four-photon polarization-entangled states. The entanglement properties of the mixed states obtained from multiphoton spontaneous parametric down-conversion are studied via witness and positive partial transpose approaches. Together with a quantification of the bipartite entanglement such analysis enables intuitive understanding of novel multiparty quantum communication protocols.