Evaluating capacities of bosonic Gaussian channels - art. no. 032312

We show how to compute or at least to estimate various capacity-related qua ntities for bosonic Gaussian channels. Among these are the coherent informa tion, the entanglement-assisted classical capacity, the one-shot classical capacity, and a quantity involving the transpose operation, shown to be a g eneral upper bound on the quantum capacity, even allowing for finite errors . All bounds are explicitly evaluated for the case of a one-mode channel wi th attenuation or amplification and classical noise.