A simple experimental scheme is proposed to generate a three-photon entangled $W$ state and a genuine four-photon entangled state $|{\chi }^{00}⟩$ that has many interesting entanglement properties and possible applications in quantum information processing. These multipartite entangled states can be generated with a certain success probability. We show that even when the quantum efficiency of the detector is $\eta =0.75$, the success probability can reach $2.8\times {10}^{-3}$ for $W$-state production and $3.0\times {10}^{-9}$ for $|{\chi }^{00}⟩$-state production. The scheme is based only on simple linear optical elements and conventional photon detectors, which greatly decrease the experimental difficulty of implementing linear optical quantum computation.

• Received 16 October 2008

DOI:https://doi.org/10.1103/PhysRevA.79.042336