Two-dimensional magneto-optical trap for neutral atoms

摘要

A two-dimensional (2D) magneto-optical trap (MOT) for alkali neutral atoms establishes a zero magnetic field along the longitudinal symmetry axis. Two of three pairs of trapping laser beams do not follow the symmetry axes of the quadruple magnetic field and are aligned with a large non-zero degree angles to the longitudinal axis. In a dark-line 2D MOT configuration, there are two orthogonal repumping beams. In each repumping beam, an opaque line is imaged to the longitudinal axis, and the overlap of these two line images creates a dark line volume in the longitudinal axis where there is no repumping light. The zero magnetic field along the longitudinal axis allows the cold atoms maintain a long ground-state coherence time without switching off the MOT magnetic field, which makes it possible to operate the MOT at a high repetition rate and a high duty cycle.