A ring magneto-optical trap

D. Felinto, Luís Gustavo Marcassa, Vanderlei Salvador Bagnato +1 more

The spatial ring-shaped distribution of atoms in a magneto-optical trap, produced by misaligned Gaussian laser beams, is investigated with respect to the increase in the number of trapped atoms. Experimental observation of the bifurcation of a single ring into a double-ring structure is reported and explained using a model that includes radiation force due to reabsorption of photons together with the conventional radiative force.

Raymond Newell

Cameron S. Fletcher, Jessica Lye, Nicholas P. Robins +1 more

I. Guedes, M. T. de Araújo, D. M. B. P. Milori +3 more

We investigated how the size of ring-shaped clouds of cold, magneto-optically trapped sodium atoms depends on the trapping parameters: magnetic-field gradient and laser intensity, detuning, and misalignment. The experiments were carried out in the low-density regime (N < 106 atoms), and the ring radius was shown to be independent of the number of trapped atoms. The results are explained with a simple model including a coordinate-dependent vortex force and the usual magneto-optical trap forces.

Martine Chevrollier, E. G. Lima, Orlando Di Lorenzo +2 more

Makoto Morinaga

We propose and experimentally demonstrate a novel scheme to magneto-optically trap neutral atoms in a ring shaped trap that can be used to transfer atoms into a circular magnetic trap with high density. This inturn enables to evaporatively cool atoms and study the behaviour of ultra cold gases in a periodic 2-dimensional potential. The circular magneto-optical trap itself is also of interest to investigate the properties of magneto-optical trap of deformed shape, such as reduction of photon-reabsorption.