Abstract

Shimizu et al. [1] demonstrated an alternative of the usual six beam magneto-optical trap (MOT), using four independent beams in a tetrahedral configuration. We demonstrate an novel version of the four beam MOT using a triplet of mirrors, as shown in Fig. 1, to split and steer an incoming beam into three parts such that all four beams cross in the correct configuration. The polarization of each reflected beam has a circular component along the local magnetic field that generates a position-dependent force. In addition, the perfect tetrahedral configuration offers a uniformly balanced radiation pressure area, and becomes suitable for efficient sub-Doppler cooling, benefiting also from the absence of retro-reflected beams. The beam overlap volume extends above the top of the mirrors, allowing scaling to smaller dimensions, as shifting the MOT center allows optical addressing from the side. In the usual pyramid configuration [2,3], the MOT forms below the top surface of the pyramid and the absence of optical access strongly reduces any manipulation of the cold atomic cloud. In addition, a micro-fabricated tetrahedral configuration offers an ideal tool for a high phase stability optical lattice, with the benefit of fixed lattice geometry.

© 2009 IEEE