Magnetic trapping of a cold Rb-Cs atomic mixture.

Abstract

We present an apparatus for the study of an ultracold gaseous atomic mixture of 133Cs and 87Rb. The mixture is prepared using a double magneto-optical trap (MOT) system in which a two-species pyramid MOT acts as a source of cold atoms for a `science' MOT. Measurements of the interspecies trap loss rate coe±cients ¯RbCs and ¯CsRb in the science MOT are reported. After the initial MOT phase, atoms in the mixture are optically pumped into the magnetically trappable jF = 3;mF = ¡3i and jF =1;mF =¡1i states of Cs and Rb (respectively) and loaded into an Io®e-Pritchard magnetic trap. We demonstrate a novel technique for limiting the interspecies loss rate in the science MOT by spatially separating the two trapped atom clouds, which greatly enhances the number of atoms which can be loaded into the magnetic trap.