https://doi.org/10.1007/s100510051077
A remark on the optimal cloning of an N-level quantum system
1
Institut für Angewandte Mathematik, Universität Bonn,
53115 Bonn,
Fakultät für Mathematik, Ruhr-Universität Bochum,
44780 Bochum, Germany
2
Institute of Physics,
Chinese Academy of Science, Beijing, P.R. China
Received:
21
September
1999
Published online: 15 April 2000
We study quantum cloning machines (QCM) that act on an unknown N-level quantum state and make M copies. We give a formula for the maximum of the fidelity of cloning and exhibit the unitary transformations that realize this optimal fidelity. We also extend the results to treat the case of M copies from N' (M>M') identical N-level quantum systems.
PACS: 03.67.-a – Quantum information / 89.70.+c – Information science / 03.65.-w – Quantum mechanics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000
