High-efficiency cold-atom transport into a waveguide trap

Abstract

We have developed and characterized an atom-guiding technique that loads $3\times10^6$ cold rubidium atoms into hollow-core optical fibre, an order-of-magnitude larger than previously reported results. This result was possible because it was guided by a physically realistic simulation that could provide the specifications for loading efficiencies of 3% and a peak optical depth of 600. The simulation further showed that the demonstrated loading efficiency is limited solely by the geometric overlap of the atom cloud and the optical guide beam, and is thus open to further improvement with experimental modification. The experimental arrangement allows observation of the real-time effects of light-assisted cold atom collisions and background gas collisions by tracking the dynamics of the cold atom cloud as it falls into the fibre. The combination of these observations, and physical understanding from the simulation, allows estimation of the limits to loading cold atoms into hollow-core fibres.