  We demonstrate an experimental realization of remote state preparation via
the quantum teleportation algorithm, using an entangled photon pair in the
polarization degree of freedom as the quantum resource. The input state is
encoded on the path of one of the photons from the pair. The improved
experimental scheme allows us to control the preparation and teleportation of a
state over the entire Bloch sphere with a resolution of the degree of mixture
given by the coherence length of the photon pair. Both the preparation of the
input state and the implementation of the quantum gates are performed in a pair
of chained displaced Sagnac interferometers, which contribute to the overall
robustness of the setup. An average fidelity above 0.9 is obtained for the
remote state preparation process. This scheme allows for a prepared state to be
transmitted on every repetition of the experiment, thus giving an intrinsic
success probability of 1.
