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Quantum cloning of orthogonal qubits

J. Fiurasek·S. Iblisdir·S. Massar·N. J. Cerf
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Abstract

An optimal universal cloning transformation is derived that produces M copies of an unknown qubit from a pair of orthogonal qubits. For M>6, the corresponding cloning fidelity is higher than that of the optimal copying of a pair of identical qubits. It is shown that this cloning transformation can be implemented probabilistically via parametric down-conversion by feeding the signal and idler modes of a nonlinear crystal with orthogonally polarized photons.

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J. Fiurasek, S. Iblisdir, S. Massar, N. J. Cerf. 2001-10-02. Quantum cloning of orthogonal qubits. https://doi.org/10.1103/physreva.65.040302

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