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Reliability of the beamsplitter based Bell-state measurement

Yoon-Ho Kim·Warren P. Grice
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Abstract

A linear 50/50 beamsplitter, together with a coincidence measurement, has been widely used in quantum optical experiments, such as teleportation, dense coding, etc., for interferometrically distinguishing, measuring, or projecting onto one of the four two-photon polarization Bell-states $|ψ^{(-)}>$. In this paper, we demonstrate that the coincidence measurement at the output of a beamsplitter cannot be used as an absolute identifier of the input state $|ψ^{(-)}>$ nor as an indication that the input photons have projected to the $|ψ^{(-)}>$ state.

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Yoon-Ho Kim, Warren P. Grice. 2003-04-09. Reliability of the beamsplitter based Bell-state measurement. https://doi.org/10.1103/physreva.68.062305

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