Evaluation of Alternative Designs for a Magneto-Optical Trap

Yiyi Deng, Dr. John Noe, Professor Harold Metcalf
Laser Teaching Center, Stony Brook University

This report examines several alternative designs for a rubidium magneto-optical trap (MOT) suitable for construction in an undergraduate laboratory. The analysis compares the characteristics of each design in terms of variables such as laser power, trapping capability, stability, ease of control, and monetary cost.

A magneto-optical trap consists of three orthogonal pairs of counter-propagating circularly polarized laser beams in an anti-Helmholtz magnetic field. Within the trap, atoms are cooled down by exchange of momentum with the photons they absorb during their random motion. The Doppler effect, resulting from laser detuning and atomic motion, generates a velocity dependent force, while the Zeeman effect, resulting from the inhomogeneous magnetic field created by the anti-Helmholtz configuration, generates a position dependent force. The ability of the MOT to cool and physically confine atoms has made possible many novel projects not otherwise possible, such as Bose-Einstein condensation, atomic lasers, and studies of the atomic spectra of radioactive isotopes such as Francium (Fr).

Despite the great complexity of a working MOT, there are a number of MOT setups which have been successfully developed in small undergraduate laboratories at, for example, Truman State University, Amherst College, and Bryn Mawr. This analysis presents a optimized hybrid design incorporating features of each setup that would be most suitable for construction in the Laser Teaching Center.

This work was supported by NSF Grant PHY 0243935