title: Optimal filters for photon cloning with an optical amplifier.
abstract: We study the performance of a practical quantum cloning scheme consisting of a continuously pumped broadband optical amplifier followed by optimal spectral and temporal filters for spontaneous emission suppression. Our simulation results demonstrate that the fidelity of this system is no better than a random cloning machine when the average input photon number is below one, but asymptotically approaches the quantum limit of an optimal quantum cloning machine as the input photon number increases. We also show that this system has a better fidelity than cloning based on state estimation, though for a large number of clones both cloning methods asymptotically approach the quantum limit.
authors.affiliation: Department of Physics and Department of Electrical and Computer Engineering, University of Toronto, Toronto, Canada. bqi@physics.utoronto.ca
authors.forename: Bing
authors.initials: B
authors.lastname: Qi
authors.forename: Li
authors.initials: L
authors.lastname: Qian