  The fidelity of a quantum transformation is strongly linked with the prior
partial information of the state to be transformed. We illustrate this
interesting point by proposing and demonstrating the superior cloning of
coherent states with prior partial information. More specifically, we propose
two simple transformations that under the Gaussian assumption optimally clone
symmetric Gaussian distributions of coherent states as well as coherent states
with known phases. Furthermore, we implement for the first time near-optimal
state-dependent cloning schemes relying on simple linear optics and
feedforward.
