title: Quantum cloning machines with phase-conjugate input modes.
abstract: A quantum cloning machine is introduced that yields M identical optimal clones from N replicas of a coherent state and N' replicas of its phase conjugate. It also optimally produces M' = M+N'-N phase-conjugate clones at no cost. For well chosen ratios N'/N, this machine is shown to provide better cloning fidelities than the standard (N+N')-->M cloner. The special cases of the optimal balanced cloner (N = N') and optimal measurement (M = infinity) are investigated.
authors.affiliation: Ecole Polytechnique, CP 165, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium.
authors.forename: N J
authors.initials: NJ
authors.lastname: Cerf
authors.forename: S
authors.initials: S
authors.lastname: Iblisdir