We report on the experimental observation and characterization of a six-photon entangled Dicke state. We obtain a fidelity as high as 0.654±0.024 and prove genuine six-photon entanglement by, amongst others, a two-setting witness yielding -0.422±0.148. This state has remarkable properties; e.g., it allows obtaining inequivalent entangled states of a lower qubit number via projective measurements, and it possesses a high entanglement persistency against qubit loss. We characterize the properties of the six-photon Dicke state experimentally by detecting and analyzing the entanglement of a variety of multipartite entangled states.
@article{arxiv.0903.2213,
title = {Experimental entanglement of a six-photon symmetric Dicke state},
author = {Witlef Wieczorek and Roland Krischek and Nikolai Kiesel and Patrick Michelberger and Geza Toth and Harald Weinfurter},
journal= {arXiv preprint arXiv:0903.2213},
year = {2009}
}