Local transformation of two einstein-podolsky-rosen photon pairs into a three-photon w state.

We propose and experimentally demonstrate a transformation of two Einstein-Podolsky-Rosen photon pairs distributed among three parties into a three-photon W state using local operations and classical communication. We then characterize the final state using quantum state tomography on the three-photon state and on its marginal bipartite states. The fidelity of the final state to the ideal W state is 0.778+/-0.043 and the expectation value for its witness operator is -0.111+/-0.043 implying the success of the proposed local transformation.