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Quantum nonlocality obtained from local states by entanglement purification

P. Walther·K. J. Resch·C. Brukner·A. M. Steinberg·J. -W. Pan·A. Zeilinger
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Abstract

We have applied an entanglement purification protocol to produce a single entangled pair of photons capable of violating a CHSH Bell inequality from two pairs that individually could not. The initial poorly-entangled photons were created by a controllable decoherence that introduced complex errors. All of the states were reconstructed using quantum state tomography which allowed for a quantitative description of the improvement of the state after purification.

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P. Walther, K. J. Resch, C. Brukner, A. M. Steinberg, J. -W. Pan, A. Zeilinger. 2005-02-03. Quantum nonlocality obtained from local states by entanglement purification. https://doi.org/10.1103/physrevlett.94.040504

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