Magneto-optical trap operating on a magnetically induced level-mixing effect

Abstract

In this work we point out a theoretical picture accounting for some unpredicted trapping conditions that have been observed---but not satisfactorily explained---in the past and have been recently confirmed by our experiments. We have realized a sodium magneto-optical trap working on the ${3}^{2}{S}_{1/2}(F=1)\ensuremath{\rightarrow}{3}^{2}{P}_{3/2}{(F}^{\ensuremath{'}}=0)$ transition that, according to the usually accepted model, should not work. Our results, with respect to the previous unexplained observations, support more stringent conclusions because our experimental setup gives us the possibility to repump atoms from the $F=2$ state using ${D}_{1}$ transitions. This definitely excludes that the repumping frequency may play a role in the trap dynamics. A peculiar perturbation approach allows us to demonstrate that the confinement force originates, in this case, from a magnetically induced level-mixing effect. Moreover, we describe separately the nature of damping and confining forces and we recognize that in this case they are due to different transitions. Trap simulations based on a dynamical three-dimensional model are presented, which quantitatively reproduce our experimental results.