An ultra-cold Rb-Cs mixture in a magnetic trap

This works reports on using laser cooling and evaporative cooling to create an ultra-cold mixture of ⁸⁷Rb and ¹³³Cs atoms inside the conservative potential of a time-averaged orbiting potential (TOP) magnetic trap. We were able to observe sympathetic cooling of Cs through collisional energy exchange with the Rb atoms, thus reaching Cs temperatures of ≈ 5 μK.