Manipulating and measuring single atoms in the Maltese cross geometry

Abstract

We describe optical methods for trapping, cooling, and observing single $^{87}$Rb atoms in a four-lens "Maltese cross" geometry (MCG). The use of four high numerical-aperture lenses in the cardinal directions enables efficient collection of light from non-collinear directions, but also restricts the optical access for cooling and optical pumping tasks. We demonstrate three-dimensional atom localization with sub-wavelength precision, and present measurements of the trap lifetime, temperature and transverse trap frequency in this geometry. We observe a trap performance comparable to what has been reported for single-atom traps with one- or two-lens optical systems, and conclude that the additional coupling directions provided by the MCG come at little cost to other trap characteristics.