title: Entanglement persistency of multiphoton entangled states.
abstract: 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.
authors.affiliation: Physics Department, Stockholm University, S-106 91 Stockholm, Sweden.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bourennane
authors.forename: Manfred
authors.initials: M
authors.lastname: Eibl
authors.forename: Sascha
authors.initials: S
authors.lastname: Gaertner
authors.forename: Nikolai
authors.initials: N
authors.lastname: Kiesel
authors.forename: Christian
authors.initials: C
authors.lastname: Kurtsiefer
authors.forename: Harald
authors.initials: H
authors.lastname: Weinfurter