Optimal phase-covariant quantum cloning

Abstract

Abstract:

In quantum information science, quantum cloning theory is a basic one that provides an absolute security of quantum cryptography. We derive the explicit transformations of the optimal 1→M=d+1 phase-covariant quantum cloning in d dimensions, and then generalize this kind of cloning machine to the 1→M=kd+1 (k integer) case and obtain the explicit transformation. By exploiting the formulation of the nonoptimal 2→M=2k+1 phase-covariant quantum cloning in 2 dimensions, we derive the optimal cloning transformation. The copy fidelities of the two kinds of cloning machines are coincident with the theoretical values found.

Key words: Quantum information, Quantum cryptography, Quantum cloning, Universal quantum cloning, Phase-covariant quantum cloning

CLC Number:

O431

Zhang Gang, Pan Guozhu, Yuan Hao. Optimal phase-covariant quantum cloning[J]. J4, 2015, 32(4): 438-444.

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