Process-optimized phase covariant quantum cloning

• URL: http://arxiv.org/abs/2107.03042v2
• Date: Thu, 7 Oct 2021 04:15:04 GMT
• Title: Process-optimized phase covariant quantum cloning
• Abstract summary: We compute the optimal global fidelity for phase-covariant cloning machines via semi-definite programming optimization. We also consider optimal simulations of the cloning and transpose cloning map, both by a direct optimization and by a composition of component-wise QCMs.
• Score: 4.974890682815778
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: After the appearance of the no-cloning theorem, approximate quantum cloning machines (QCMs) have become one of the most well-studied subject in quantum information theory. Among several measures to quantify the performance of a QCM, single-qudit fidelity and global fidelity have been most widely used. In this paper we compute the optimal global fidelity for phase-covariant cloning machines via semi-definite programming optimization, thereby completing a remaining gap in the previous results on QCMs. We also consider optimal simulations of the cloning and transpose cloning map, both by a direct optimization and by a composition of component-wise optimal QCMs. For the cloning map the composition method is sub-optimal whereas for the transpose cloning map the method is asymptotically optimal.

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