Journal of the Korean Physical Society

Systematic study of the rf-induced evaporation of 87Rb atoms in a spherical magnetic quadrupole trap

Dahyun Yum, Jina Park, Wanhee Lee, Wonho Jhe

Published Jan 1, 2012• 5 citations

Abstract

We trap 87 Rb atoms in a spherical magnetic quadrupole potential consisting of a pair of anti-Helmholtz coils. The number of trapped atoms is 2.16(7)×10 8 , and the lifetime is 26 seconds. The number, the temperature and the size of the atoms in a magnetic trap are controlled by the forced rfevaporative cooling technique. We obtain a sub-Doppler temperature of 33.7(5) μK in these atoms at an evaporation frequency of 4.2 MHz in the magnetic quadrupole trap. We discuss the properties of the atoms in the spherical magnetic quadrupole trap and the results of the rf-evaporation process.

DOI: 10.3938/jkps.60.1

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Journal of the Korean Physical Society

Systematic study of the rf-induced evaporation of 87Rb atoms in a spherical magnetic quadrupole trap

Dahyun Yum, Jina Park, Wanhee Lee, Wonho Jhe

Published Jan 1, 2012• 5 citations

Publisher

Abstract

DOI: 10.3938/jkps.60.1

Related papers

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We report on an efficient rf-induced forced evaporative cooling of an ensemble of

^{87}\mathrm{Rb}

atoms in state $|F=2,{m}_{F}=2\ensuremath{\rangle}$ magnetically trapped in a quadrupole-Ioffe configuration trap. The cigar-shaped trap is oriented with its weak confining axis along the direction of gravity leading to, first, a significant separation of the trapping positions for low-field-seeking atoms with different

{m}_{F}

value and, second, a reduced resonance volume for rf-induced evaporation confined to a small region around the lower tip of the cigar-shaped ensemble. This results in an enhancement of the evaporation efficiency $\ensuremath{\alpha}\ensuremath{\equiv}d\mathrm{ln}T/(d\mathrm{ln}N)$ due to either reduced or completely vanishing scattering events between cooled and evaporated atoms. We present data illustrating this effect.

{}^{87}\mathrm{Rb}

atoms are first loaded into the linear trapping potential of a magnetic quadrupole, which is then converted into the parabolic geometry of an Ioffe trap. During this process two spherical quadrupole traps with perpendicular axes merge and the trapped atomic cloud moves close to the magnetic field producing coils, resulting in tight confinement of the atoms while the power dissipation of the trap remains low. The magnetically trapped atoms are cooled to below the phase transition of Bose-Einstein condensation by rf-induced evaporation.