Large-bandwidth photonic storage and manipulation with cold and ultracold atoms

In the quest for optical quantum memories that are compatible with common single-photon sources, and which can be integrated into land- and satellite-based optical quantum communications networks, atoms play an important role for providing large-bandwidth and long storage time possibilities, using wavelengths that can be integrated into anticipated standard systems. In our experiments, we use both the conventional "fast" and the Autler-Townes protocols to realize large-bandwidth storage and manipulations of photonic signals, leading to fast and relatively low-noise signals, all of which can be implemented using minimal experimental resources. We demonstrated these protocols using laser-cooled and Bose-condensed atoms as the storage medium, and explored how the performance of each approach could be optimised [in terms of noise, efficiency, and resource requirements (laser power/optical depth)] under realistic parameters. Looking forward, we consider the potential for these protocols to contribute to tasks including wavelength conversion, multimode storage, and quantum information processing.