Rapid production ofR87bBose-Einstein condensates in a combined magnetic and optical potential

Abstract

We describe an apparatus for quickly and simply producing 87 Rb Bose-Einstein condensates. It is based on a magnetic quadrupole trap and a red detuned optical dipole trap. We collect atoms in a magneto-optical trap (MOT) and then capture the atom in a magnetic quadrupole trap and force rf evaporation. We then transfer the resulting cold, dense cloud into a spatially mode-matched optical dipole trap by lowering the quadrupole field gradient to below gravity. This technique combines the efficient capture of atoms from a MOT into a magnetic trap with the rapid evaporation of optical dipole traps; the approach is insensitive to the peak quadrupole gradient and the precise trapping beam waist. Our system reliably produces a condensate with N ≈ 2 × 10 6 atoms every 16 s.

Long-time-scale dynamics of spin textures in a degenerateF=187Rb spinor Bose gas

“…[22], with initial temperatures of 30 μK and initial trap frequencies of (ω x ,ω y ,ω z ) = 2π × (220,4150,63) Hz in a focused, linearly polarized light beam with a wavelength of 1064 nm. We next prepare unmagnetized spin mixtures with fractional populations in the three Zeeman sublevels, ζ (th) m F with m F = {+1,0,−1}, by the application of resonant π/2 rf pulses in the presence of a magnetic-field gradient [8].…”

Dual-species Bose-Einstein condensate ofRb87andCs133McCarron1, Cho2, Jenkin3 et al. 2011Phys. Rev. A245122680View full textAdd to dashboardCite

“…This increase results from an effect analogous to the use of a dimple potential [28]. Adiabatic expansion of the trap volume cools the cloud in the quadrupole potential and elastic collisions transfer some atoms into the tighter harmonic optical potential [35]. The remaining atoms are lost from the quadrupole trap reservoir, removing energy in the process.…”

“…We continue this cooling until Majorana losses begin to limit the lifetime of the sample. At this stage the crossed dipole trap is loaded via elastic collisions by simply reducing the magnetic field gradient to 29 G/cm, just below the 30.5 G/cm (31.1 G/cm) required to levitate 87 Rb ( 133 Cs) [35]. At the same time the final rf frequency is adjusted to control the composition of the mixture loaded into the dipole trap.…”

Fast closed-loop optimal control of ultracold atoms in an optical lattice

“…A degenerate sample of 87 Rb is obtained in a hybrid magneto-optical trap realized with the superposition of a quadrupolar magnetic field and a focused red-detuned laser beam [27]. After evaporative cooling, we obtain a BEC of about 2 × 10 5 atoms experiencing an external harmonic potential with cylindrical symmetry [28].…”