We have developed and characterized an atom-guiding technique that loads 3 × 10 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 3.0 % 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 hollowcore fibres.

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We present an optical approach to compensating for spatially varying ac-Stark shifts that appear on atomic ensembles subject to strong optical control or trapping fields. The introduction of an additional weak light field produces an intentional perturbation between atomic states that is tuned to suppress the influence of the strong field. The compensation field suppresses sensitivity in one of the transition frequencies of the trapped atoms to both the atomic distribution and motion. We demonstrate this technique in a cold rubidium ensemble and show a reduction in inhomogeneous broadening in the trap. This two-colour approach emulates the magic trapping approach that is used in modern atomic lattice clocks but provides greater flexibility in choice of atomic species, probe transition, and trap wavelength.

We develop a method for extracting the physical parameters of interest for a conventional dipoletrapped cold atomic ensemble. This technique uses the spatially dependent ac-Stark shift of the trap itself to project the atomic distribution onto a light-shift broadened transmission spectrum. We develop a model that connects the atomic distribution with the expected transmission spectrum. We then demonstrate the utility of the technique by deriving the temperature, trap depth, lifetime, and trapped atom number from data that was taken in a single shot experimental measurement.

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