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Quantum information becomes classical when distributed to many users

G. Chiribella·G. M. D'Ariano
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Abstract

Any physical transformation that equally distributes quantum information over a large number M of users can be approximated by a classical broadcasting of measurement outcomes. The accuracy of the approximation is at least of the order 1/M. In particular, quantum cloning of pure and mixed states can be approximated via quantum state estimation. As an example, for optimal qubit cloning with 10 output copies, a single user has error probability p > 0.45 in distinguishing classical from quantum output--a value close to the error probability of the random guess.

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G. Chiribella, G. M. D'Ariano. 2007-01-31. Quantum information becomes classical when distributed to many users. https://doi.org/10.1103/physrevlett.97.250503

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