Magic wavelengths of the Sr ($5s^2\;^1\!S_0$--$5s5p\;^3\!P_1$) intercombination transition near the $5s5p\;^3\!P_1$--$5p^2\;^3\!P_2$ transition

Abstract: Predicting magic wavelengths accurately requires precise knowledge of electric-dipole matrix elements of nearby atomic transitions. As a result, measurements of magic wavelengths allow us to test theoretical predictions for the matrix elements that frequently can not be probed by any other methods. Here, we calculate and measure a magic wavelength near $473$ nm of the $5s^2\,^1!S_0 - 5s5p\,^3!P_1$ intercombination transition of ${}^{88}$Sr. Experimentally, we find $473.361(4)$ nm for $\Delta m=0$ ($\pi$ transition) and $473.133(14)$ nm for $\Delta m=-1$ ($\sigma^{-}$ transition). Theoretical calculations yield $473.375(22)$~nm and $473.145(20)$ nm, respectively. The $^3!P_1$ polarizability is dominated by the contributions to the $5p^2\, ^3!P$ levels and excellent agreement of theory and experiment validates both theoretical values of these matrix elements and estimates of their uncertainties.