Experimental Single-Impulse Magnetic Focusing of Launched Cold Atoms

Three-dimensional magnetic focusing of cold atoms with a single magnetic impulse has been observed for the first time. We load 7×10 Rb atoms into a magneto-optical trap, precool the atoms with optical molasses, then use moving molasses to launch them vertically through 20.5 cm to the apex of flight. In transit the atoms are optically pumped, prior to the single magnetic lens impulse that occurs 16.5 cm above the MOT. Fluorescence images at the apex of flight characterise the widths of the focussed cloud. Results were obtained for four different configurations of the baseball lens, which tuned the relationship between the axial and radial frequencies of the lens. Compact focused clouds were seen for all four configurations. PACS numbers: 03.75.Be, 32.80.Pj, 39.25.+k