title: Cloning of continuous quantum variables
abstract: The cloning of quantum variables with continuous spectra is analyzed. A Gaussian quantum cloning machine is exhibited that copies equally well the states of two conjugate variables such as position and momentum. It also duplicates all coherent states with a fidelity of 2/3. More generally, the copies are shown to obey a no-cloning Heisenberg-like uncertainty relation.
authors.affiliation: Ecole Polytechnique, CP 165, Universite Libre de Bruxelles, 1050 Brussels, Belgium and Information and Computing Technologies Research Section, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA.
authors.initials: NJ
authors.lastname: Cerf
authors.initials: A
authors.lastname: Ipe
authors.initials: X
authors.lastname: Rottenberg