NANOFI · Nanofiber-Trapped Cold Atoms and Applications

Nanofiber-Trapped Cold Atoms and Applications

In quantum information science, two important challenges are the development of efficient optical quantum memories and reliable sources of single-photons. A promising category of such devices is based on ensembles of cold neutral atoms. The motivation comes from the fact that collective effects related to large number of atoms make it much easier to achieve a strong and controllable coupling between the medium and the light. The NANOFI project realised at Laboratoire Kastler Brossel in Paris aimed at addressing those problems, by performing experiments based on an ensemble of cold atoms trapped in the vicinity of a nanofiber, which will enable to obtain a larger optical thickness, a better coupling between collective excitations and light modes, and thus a larger efficiency than previous ensemble-based implementations. The project investigated this platform for light-matter interfacing and its possible applications. Three overall objectives were pursued and obtained. The first one was the implementation of an all-fibered trap for atoms around a nanofiber where not only large optical thicknes was observed but also atomic ordering was achieved. Using this trap, and in particular, the atomic ordering, it was possible to create conditions for a Bragg reflection from the trapped atoms, where reflections as high as 75% were observed for pulses at the single-photon level. Finally, using this setting, heralding and retrieval of single excitations into atomic chains were observed, and the generation of high-purity heralded single photons was achieved.

Data: CORDIS, © European Union