Deceleration and trapping of polar molecules

Summary form only given. There is currently a rapidly growing interest in the physics of cold molecules in general, and in the physics of cold polar gases in particular. This interest stems, for instance, from the anticipated importance of the anisotropic interaction between electric dipoles on the formation of a molecular Bose Einstein condensate, from the possibility to use single component cold polar gases for the observation of the superfluid transition, and from the possibility to use arrays of trapped polar molecules for quantum computation. There are now three techniques via which samples of trapped cold molecules have been produced. Photo association of trapped alkali atoms has been used to produce translationally cold alkali dimers, which have subsequently been trapped in a far off resonance optical trap and, more recently, in a quadrupole magnetic trap. Magnetic trapping of paramagnetic molecules thermalized in a He buffer gas has been demonstrated as well. In the third method, explored in our laboratory and detailed in this presentation, time varying electric fields are used to first decelerate pulsed beams of polar molecules, after which bunches of these slow molecules are electrostatically confined. Inthe most recent experiments, it is demonstrated that in a single deceleration and loading cycle, both (bosonic) 14ND3 and (fermionic) 15ND3 ammonia isotopomers can be trapped, even simultaneously, at densities higher than 10 cm³ and at temperatures of around 25 mK.