Rapid generation of metastable helium Bose-Einstein condensates

Abstract

We report the realisation of Bose-Einstein condensation (BEC) of metastable helium atoms using an in-vacuum coil magnetic trap and a crossed beam optical dipole trap. A novel quadrupole-Ioffe configuration (QUIC) magnetic trap made from in-vacuum hollow copper tubes provides fast switching times while generating traps with a 10G bias, without compromising optical access. The bias enables in-trap 1D doppler cooling to be used, which is the only cooling stage between the magneto-optic trap (MOT) 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 seconds, with essentially pure BECs observed with $\sim 10^6$ atoms after evaporative cooling in the dipole trap.