  We report on the coherent quantum state transfer from a two-level atomic
system to a single photon. Entanglement between a single photon (signal) and a
two-component ensemble of cold rubidium atoms is used to project the quantum
memory element (the atomic ensemble) onto any desired state by measuring the
signal in a suitable basis. The atomic qubit is read out by stimulating
directional emission of a single photon (idler) from the (entangled) collective
state of the ensemble. Faithful atomic memory preparation and read-out are
verified by the observed correlations between the signal and the idler photons.
These results enable implementation of distributed quantum networking.
