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Experimental Observation of Four-Photon Entangled Dicke State with High Fidelity

Nikolai Kiesel·Christian Schmid·Geza Toth·Enrique Solano·Harald Weinfurter
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Abstract

We present the experimental observation of the symmetric four-photon entangled Dicke state with two excitations $|D_{4}^{(2)}>$. A simple experimental set-up allowed quantum state tomography yielding a fidelity as high as $0.844 \pm 0.008$. 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 GHZ and W class. Furthermore, we discuss possible applications of $|D_{4}^{(2)}>$ in quantum communication.

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Nikolai Kiesel, Christian Schmid, Geza Toth, Enrique Solano, Harald Weinfurter. 2006-06-28. Experimental Observation of Four-Photon Entangled Dicke State with High Fidelity. https://doi.org/10.1103/physrevlett.98.063604

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