Process-optimized phase covariant quantum cloning
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.
Cite
@article{arxiv.2107.03042,
title = {Process-optimized phase covariant quantum cloning},
author = {Chloe Kim and Eric Chitambar},
journal= {arXiv preprint arXiv:2107.03042},
year = {2022}
}