LiBEC · Light scattering in Bose Einstein Condensates

Most of the recent and striking advantages in the field of quantum and nonlinear optics weremade possible due to the development of novel optical media with unprecedentedproperties. Performing a complete investigation on the behavior of light in well-defined structures or random media has indeed a huge impact in a very broad context ranging from materials engineering to biological imaging, from astrophysics to telecommunications. Concerning this, the proposal will overcome the limitations of commonly employed solid state devices, studying light emission and propagation in the advantaged framework of ultracold atomic gases. In particular it will clarify the main mechanisms that can trap photons in three dimensions. In the realization of this proposal we will employ an ultracold cloud of Rb87 atoms, whose density and shape are highly controllable by means of laser dipole traps and optical lattices. The innovative tool that we will use is a high energy focused electron beam. The inelastic impacts of electrons and atoms cause excitations of the latter by dipole transitions and subsequent re-emission of single resonant photons inside the vapour. To our knowledge, this is the only experiment where single photons are locally generated inside a cluster of controllable scatterers. We will measure the escape rate and the time correlation of the photons produced inside the cloud with this novel technique, varying the parameters of the atomic sample (density, temperature..) and of the electronic beam (current, dwell time..). This will allow us to investigate fascinating phenomena like multiple scattering, cooperative effects and Anderson localization of light in three dimensions. We will finally extend the above analysis to the case of atoms organized in periodic structures by mean of optical lattices, in order to realize an ideal simulator for photonic crystals. The IEF project will consolidate the fellow’s aim to reach an independent position at a university in Europe.