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A method for reaching detection efficiencies necessary for optical loophole-free Bell experiments

Mladen Pavicic
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Abstract

A method for preparing a loophole-free four-photon Bell experiments which requires a detection efficiency of 67% is proposed. It enables realistic detection efficiencies of 75% at a visibility of 85%. Two type-II crystals each down convert one correlated photon pair and we entangle one photon from one pair with one photon from the other pair on a highly transparent beam splitter. The entanglement selects two other conjugate photons into a Bell state. Wide solid angles for the conjugate photons then enable us to collect close to 100% of them. The cases when both photon pairs come from only one of the two crystals are successfully taken into account. Hardy's equalities are discussed.

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Mladen Pavicic. 1999-07-09. A method for reaching detection efficiencies necessary for optical loophole-free Bell experiments. https://doi.org/10.1016/s0030-4018(97)00285-x

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