  We study the Braunstein-Kimble setup for teleportation of quantum state of a
single mode of optical field. We assume that the sender and receiver share a
two-mode Gaussian state and we identify optimum local Gaussian operations that
maximize the teleportation fidelity. We consider fidelity of teleportation of
pure Gaussian states and we also introduce fidelity of the teleportation
transformation. We show on an explicit example that in some cases the optimum
local operation is not a simple unitary symplectic transformation but some more
general completely positive map.
