Fidelity of an Optical Memory Based on Stimulated Photon Echoes

We investigated the preservation of information encoded into the relative phase and amplitudes of optical pulses during storage and retrieval in an optical memory based on stimulated photon echo. By interfering photon echoes produced in a single-mode $\mathrm{Ti}\mathrm{\text{:}}\mathrm{Er}\mathrm{\text{:}}{\mathrm{LiNbO}}_{3}$ waveguide, we found that decoherence in the medium translates only as loss and not as degradation of information. We measured a visibility for interfering echoes close to 100%. These results may have important implications for future long-distance quantum communication protocols.