Figure 1: False-color plots of ⁸⁷Rb atoms undergoing Bose-Einstein condensation in a combined magnetic and optical potential. The atom number in the BEC is ~2 &times 10⁵.

Atom: ⁸⁷Rb, |F=1, m_F = -1>

Trap: Combined magnetic and optical potential. Radial confinement is produced by a single dipole beam with a 65 &microm waist. The beam is positioned ~75 &microm below the field zero of a quadrupole field such that the quadrupole potential provides axial confinement.

Method:

• 4 &times 10⁸ atoms are loaded into a UHV MOT from a pyramid MOT, 60% are transferred into a magnetic quadrupole trap. At 187 G/cm T = 160 &microK and PSD ~ 10^-7.
• After 30 s of RF evaporation in the quadrupole trap N = 2.6 &times 10⁷, T = 30 &microK and PSD ~ 10^-4.
• 20% of the atoms are transferred into the combined potential by ramping the axial quadrupole gradient down to 29 G/cm. Here T = 6 &microK and PSD ~ 10^-3.
• Evaporative cooling, by ramping down the dipole beam power, for 23 s enables us to reach BEC.
• The onset of BEC is observed with N ~ 10⁶ and the critical temperature ~ 350 nK. The pure condensate atom number ~ 2 x 10⁵.

  
  Figure 2: The team from L to R: Daniel Jenkin, Simon Cornish, Hung Wen Cho and Danny McCarron.