Quantum cloning of orthogonal qubits

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.

4 pages, 1 figure, RevTeX 4

References in corpus (3)

• Optimizing Completely Positive Maps using Semidefinite Programming
• Extremal equation for optimal completely-positive maps
• Phase-Conjugated Inputs Quantum Cloning Machines

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• The roles of quantum correlations in quantum cloning