All-Optical Realization of an Atom Laser

We demonstrate an atom laser using all-optical techniques. A Bose-Einstein condensate of rubidium atoms is created by direct evaporative cooling in a quasistatic dipole trap realized with a single, tightly focused ${\mathrm{C}\mathrm{O}}_2$-laser beam. An applied magnetic field gradient allows the formation of the condensate in a field-insensitive $m_F=0$ spin projection only, which suppresses fluctuations of the chemical potential from stray magnetic fields. A collimated and monoenergetic beam of atoms is extracted from the Bose-Einstein condensate by continuously lowering the dipole trapping potential in a controlled way to form a novel type of atom laser.