title: Experimental analysis of a four-qubit photon cluster state.
abstract: Linear-optics quantum logic operations enabled the observation of a four-photon cluster state. We prove genuine four-partite entanglement and study its persistency, demonstrating remarkable differences from the usual Greenberger-Horne-Zeilinger (GHZ) state. Efficient analysis tools are introduced in the experiment, which will be of great importance in further studies on multiparticle entangled states.
authors.affiliation: Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany.
authors.forename: Nikolai
authors.initials: N
authors.lastname: Kiesel
authors.forename: Christian
authors.initials: C
authors.lastname: Schmid
authors.forename: Ulrich
authors.initials: U
authors.lastname: Weber
authors.forename: Géza
authors.initials: G
authors.lastname: Tóth
authors.forename: Otfried
authors.initials: O
authors.lastname: Gühne
authors.forename: Rupert
authors.initials: R
authors.lastname: Ursin
authors.forename: Harald
authors.initials: H
authors.lastname: Weinfurter