High-precision measurements of the $^{87}$Rb vector polarizability

We report progress on an experiment to measure the vector polarizability of $^{87}$Rb atoms in the $ F = 2 $ ground hyperfine state between the $D1$ and $D2$ spectral lines. The experiment uses a condensate interferometer to measure a tune-out wavelength, the light wavelength at which the ac electric polarizability of the atom equals zero. The location of the tune-out wavelength depends on the optical polarization of the light, and the vector polarizability characterizes this dependence. This can be compared to previous measurements by our group of tune-out wavelengths for the scalar polarizability alone. Measurements of the vector polarizability and tune-out wavelengths near multiple atomic states allows the identification of individual contributions to the polarizability from higher-lying states and from the core electrons. Accurate knowledge of these contributions would be useful as a theoretical benchmark and for improved analysis of atomic parity violation experiments.