Rapid production of large Li-7 Bose-Einstein condensates using D-1 gray molasses

Abstract

We demonstrate the production of large Li-7 Bose-Einstein condensates in an optical dipole trap using D-1 gray molasses. The sub-Doppler cooling technique reduces the temperature of 4 x 10(9) atoms to 25 mu K in 3 ms. After microwave evaporation cooling in a magnetic quadrupole trap, we transfer the atoms to a crossed optical dipole trap, where we employ a magnetic Feshbach resonance on the vertical bar F = 1, m(F) = 1 > state. Fast evaporation cooling is achieved by tilting the optical potential using a magnetic field gradient on the top of the Feshbach field. Our setup produces pure condensates with 2.7 x 10(6) atoms in the optical potential for every 11 s. The trap tilt evaporation allows rapid thermal quench, and spontaneous vortices are observed in the condensates as a result of the Kibble-Zurek mechanism.