Precise determination of atomic g-factor ratios from a dual isotope magneto-optical trap

We demonstrate a technique, for carrying out precise measurements of atomic g-factor ratios, which relies on measurements of Larmor oscillations from coherences between magnetic sublevels in the ground states of $^{85}$Rb and $^{87}$Rb atoms confined in a dual isotope magneto-optical trap. We show that a measurement of $g^{(87)}_{F} /g^{(85)}_{F}$ with a resolution of 0.69 parts per $10^6$ is possible by recording the ratio of Larmor frequencies in the presence of a constant magnetic field. This represents the most precise single measurement of $g^{(87)}_{F} /g^{(85)}_{F}$ without correcting for systematic effects (I. Chan et al., Phys. Rev. A \textbf{84}, 032509 (2011)).