Experiments to Control Atom Number and Phase-Space Density in ...

Figure 8.11: Different shapes of MOT compression curves. The detuning of the MOT
beams is ramped linearly in all of these cases.
(black) leads to the best atom number in the optical dipole trap. (The number of atoms
in the MOT before loading, and the final MOT beam detuning is kept constant to ensure
fair comparison.) Table 8.1 summarizes the different shapes of the compression curves
used and the corresponding atom number loaded into the optical dipole trap. The atom
number is determined after 1 second holding in the CO2 dipole trap. This ensures that
all atoms not captured in the dipole trap are removed. This data was taken before
the problem of the optical dipole trap lifetime was solved, see section 8.5, and thus the
number loaded into the trap was actually larger than the numbers reported in table 8.1.
Curve Fitted curve shape atom number
1 6.22−6.20·sin 2 (0.00115·(t+55.199) 2 ) (8.19±0.72)×10 5
2 5.80−0.340·exp( t
3.53
) (3.38 ± 0.04)×105
3 0.0146+646·(1−exp(− (t+4.30)
2.51 )) 7.69 · exp(− (t+4.30)
1.32 ) (5.34±0.68)×10 5
4 −0.160+5.69·sin 2 (0.147(t+10.5)) (7.97± 0.60)×10 5
5 5.51−0.549·t (3.78±0.56)×10 5
Table 8.1: Transfer into optical dipole trap for different compression curves. The atom
number is determined 1 second after the MOT has been turned off, to ensure that only
atoms in the optical dipole trap are counted.
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