Rapid generation of metastable helium Bose-Einstein condensates

Abstract

We report the realization of Bose-Einstein condensation (BEC) of metastable helium atoms using an in-vacuum coil magnetic trap and a crossed-beam optical dipole trap. A quadrupole-Ioffe configuration magnetic trap made from in-vacuum hollow copper tubes provides fast switching times while generating traps with a 10-G bias, without compromising optical access. The bias enables in-trap one-dimensional Doppler cooling to be used, which is the only cooling stage between the magneto-optic trap and the optical dipole trap. This allows direct transfer to the dipole trap without the need for any additional evaporative cooling in the magnetic trap. The entire experimental sequence takes 3.3 s, with essentially pure BECs observed with ∼106 atoms after evaporative cooling in the dipole trap.