Probabilistic Cloning of Coherent States without a Phase Reference
  We present a probabilistic cloning scheme operating independently of any phase reference. The scheme is based solely on a phase-randomized displacement and photon counting, omitting the need for non-classical resources and non-linear materials. In an experimental implementation, we employ the scheme to clone coherent states from a phase covariant alphabet and demonstrate that the cloner is capable of outperforming the hitherto best-performing deterministic scheme. An analysis of the covariances between the output states shows that uncorrelated clones can be approached asymptotically. An intriguing feature is that the trade-off between success rate and achieved fidelity can be optimized even after the cloning procedure. 
Christian R. M\"uller, Christoffer Wittmann, Petr Marek, Radim Filip,   Christoph Marquardt, Gerd Leuchs and Ulrik L. Andersen
quant-ph