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Realization of the 1->3 optimal phase-covariant quantum cloning machine

Fabio Sciarrino·Francesco De Martini
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Abstract

The 1->3 quantum phase covariant cloning, which optimally clones qubits belonging to the equatorial plane of the Bloch sphere, achieves the fidelity Fcov(1->3)=0.833, larger than for the 1->3 universal cloning Funiv(1->3)=0.778. We show how the 1->3 phase covariant cloning can be implemented by a smart modification of the standard universal quantum machine by a projection of the output states over the symmetric subspace. A complete experimental realization of the protocol for polarization encoded qubits based on non-linear and linear methods will be discussed.

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Fabio Sciarrino, Francesco De Martini. 2004-12-06. Realization of the 1->3 optimal phase-covariant quantum cloning machine. https://doi.org/10.1103/physreva.72.062313

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