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Demonstrating multipartite entanglement of single-particle W states: linear optical schemes

Hyunchul Nha·Jaewan Kim
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Abstract

We present two linear optical schemes using nonideal photodetectors to demonstrate inseparability of W-type N-partite entangled states containing only a single photon. First, we show that the pairwise entanglement of arbitrary two modes chosen from N optical modes can be detected using the method proposed by Nha and Kim [Phys. Rev. A 74, 012317 (2006)], thereby suggesting the full inseparability among N parties. In particular, this scheme is found to succeed for any nonzero quantum efficiency of photodetectors. Second, we consider a quantum teleportation network using linear optics without auxiliary modes. The conditional teleportation can be optimized by a suitable choice of the transmittance of the beam splitter in the Bell measurement. Specifically, we identify the conditions under which maximum fidelity larger than classical bound 2/3 is achieved only in cooperation with other parties. We also investigate the case of on-off photodetectors that cannot discriminate the number of detected photons.

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Hyunchul Nha, Jaewan Kim. 2007-02-21. Demonstrating multipartite entanglement of single-particle W states: linear optical schemes. https://doi.org/10.1103/physreva.75.012326

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