https://doi.org/10.1140/epjd/e2010-00032-9
High-fidelity copies from a symmetric 1→2 quantum cloning machine
1
Max-Planck-Institut für Kernphysik, Postfach 103980, 69029 Heidelberg, Germany
2
Physikalisches Institut, Heidelberg
Universität, 69120 Heidelberg, Germany
3
Department of Physical Sciences, P.O. Box 3000, University of Oulu, 90014 Oulu, Finland
4
Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany
Corresponding author: siomau@physi.uni-heidelberg.de
Received:
15
December
2009
Revised:
25
January
2010
Published online:
16
February
2010
A symmetric 1→2 quantum cloning machine
(QCM) is presented that provides high-fidelity copies with
0.90≤ F≤0.95 for all pure (single-qubit) input states
from a given meridian of the Bloch sphere. Emphasize is placed
especially on the states of the (so-called) Eastern meridian, that
includes the computational basis states |0〉,|1〉
together with the diagonal state , for which suggested cloning
transformation is shown to be optimal. In addition, we also show
how this QCM can be utilized for eavesdropping in Bennett's B92
protocol for quantum key distribution with a substantial higher
success rate than obtained for universal or equatorial quantum
copying.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2010