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Q: Fachverband Quantenoptik und Photonik
Q 62: Ultrakalte Atome (Fallen und Kühlung)
Q 62.3: Talk
Friday, March 14, 2008, 14:30–14:45, 3B
Trapping of rubidium atoms by ac electric fields — •Sophie Schlunk1,2, Adela Marian1, Wieland Schöllkopf1, and Gerard Meijer1 — 1Fritz-Haber-Institut, Berlin, Germany — 2FOM Institute for Plasma Physics Rijnhuizen, Nieuwegein, The Netherlands
We have demonstrated trapping of ultracold ground-state Rb atoms in a macroscopic ac electric trap [S. Schlunk et al., PRL 98, 223002 (2007)]. AC electric trapping has been previously demonstrated for polar molecules [H. L. Bethlem et al., PRA 74, 063403 (2006)], as well as for Sr atoms on a chip [T. Kishimoto et al., PRL 96, 123001 (2006)], and recently for Rb atoms in a three-phase electric trap [T. Rieger et al., PRL 99, 063001 (2007)]. AC traps for neutral particles operate analogously to Paul traps for ions. A potential energy surface is created with a saddle point at the trap center, resulting in attractive forces (focusing) in one direction and repulsive forces (defocusing) along the other two directions. Alternating between the two electric field configurations leads to dynamic confinement of the particles.
In the experiment, the Rb atoms are cooled in a standard MOT and loaded into a magnetic trap. The magnetically trapped cloud is then transferred into a second vacuum chamber housing the ac trap. Stable electric trapping is observed in a narrow range of switching frequencies around 60 Hz, in agreement with trajectory calculations. We have trapped about 2 × 105 atoms with lifetimes on the order of 9 s. Absorption images of the atom cloud taken at various phases of the ac switching cycle show different shapes reflecting the focusing and defocusing forces acting on the atoms.