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Optimal Non-Universally Covariant Cloning

G. M. D'Ariano·P. Lo Presti
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Abstract

We consider non-universal cloning maps, namely cloning transformations which are covariant under a proper subgroup G of the universal unitary group U(d), where d is the dimension of the Hilbert space H of the system to be cloned. We give a general method for optimizing cloning for any cost-function. Examples of applications are given for the phase-covariant cloning (cloning of equatorial qubits) and for the Weyl-Heisenberg group (cloning of "continuous variables").

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G. M. D'Ariano, P. Lo Presti. 2001-01-19. Optimal Non-Universally Covariant Cloning. https://doi.org/10.1103/physreva.64.042308

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