Population dynamics in a metastable neon magneto-optical trap

Abstract

We observe the population dynamics within a metastable neon magneto-optical trap (MOT) through the measurement of the average squared Clebsch-Gordan coefficient C 2 over a range of laser detunings. The magnitude of C 2 is dependent on the internal quantum state of an atom interacting with the light field and is found to show a strong dependence on the applied laser detuning. Previously it has been reported [Townsend et al., Phys. Rev. A 52, 1423 (1995)] that trapped atoms in a MOT are pumped towards the states that interact most strongly with the local field and therefore the measured value of C 2 is larger than the average over all possible transitions. For the 3 P 2 -to- 3 D 3 cooling transition in metastable neon the average C 2 value is equal to 0.46; however, we have measured 0.29 ± 0.03 < C 2 < 0.73 ± 0.09 . We explain this range of values for C 2 by considering the possible transition rates between the different magnetic sublevels in the system. This result has significant consequences when trap populations are measured via fluorescence in a MOT.