Abstract

The magneto-optical trap (MOT),¹ has found widespread use for trapping neutral atoms. The increasing possibility of employing cold atoms in a variety of experiments² has driven some effort to obtain simpler and more efficient trapping configurations with peculiar properties not attained in the usual MOT.³ However, the implement of new trap designs is rather complicated, due to the necessity of providing three-dimensional cooling andconfinement.⁴ We report on the experimental realization of new schemes for magneto-optical trapping of neutral atoms, using either two or four laser beams. The two-beam trap (TBT) consists of just one pair of focused, red-detuned, laser beams having opposite circular polarizations in a quadrupole magnetic field. The four-beam trap (FBT) needs one additional pair of counter propagating laser beams added perpendicularly to the direction of the focused beams as shown schematically in Fig. 1. The laser polarizations are arranged similar to the usual MOT. For the TBT, z-di-rection stability is achieved by the conventional MOT trapping force, which can overcome the nonrestoring force, due to intensity imbalance. However, transverse confinement is basically due to the spontaneous force associated with the beam geometry. We notice that the existing cooling along z-direction might be expected to be weaker in the transverse direction.

© 1994 IEEE