The achievement of excellent control of the motional and the internal quantum states of ultracold neutral atoms and ions has opened intriguing possibilities for quantum simulation and quantum computation. In quantum degenerate neutral atoms many-body effects have been explored with hundreds of thousands of atoms and coherent light-matter interfaces have been built. Single or few trapped ions have been employed to demonstrate universal quantum computing algorithms and to detect variations of fundamental constants in precision atomic clocks. Until now quantum gases and single trapped ions have been disconnected in experiments. Their complementarities suggest, however, that they could be advantageously combined into one hybrid system. We have explored the immersion of a single trapped ion into a Bose-Einstein condensate of neutral atoms. We demonstrate the full independent control over the two systems, study the fundamental interaction processes, and observe sympathetic cooling of a single ion by immersion into a Bose-Einstein condensate. Our experiment opens possibilities for continuous cooling of a quantum computer and for exploring entanglement in hybrid quantum systems.
10 min talk title: Large spin relaxation rates in trapped submerged-shell atoms