Abstract
We present the experimental observation of the symmetric four-photon entangled Dicke state with two excitations . A simple experimental setup allowed quantum state tomography yielding a fidelity as high as . We study the entanglement persistency of the state using novel witness operators and focus on the demonstration of a remarkable property: depending on the orientation of a measurement on one photon, the remaining three photons are projected into both inequivalent classes of genuine tripartite entanglement, the Greenberger-Horne-Zeilinger and class. Furthermore, we discuss possible applications of in quantum communication.
- Received 25 June 2006
DOI:https://doi.org/10.1103/PhysRevLett.98.063604
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