Multi-species atom interferometry

Our nanograting atom interferometer now works with Na, K, and Rb atom beams. We also have studied diffraction of Li, Sr, and He* in the same apparatus. Comparing results from several atomic species provides new scientific opportunities. We measured ratios of atomic polarizabilities ($\alpha_{\textrm{K}} / \alpha_{\textrm{Na}}$, $\alpha_{\textrm{Rb}} / \alpha_{\textrm {Na}}$ , and $\alpha_{\textrm{Rb}} / \alpha_{\textrm{K}}$) each with 0.3\% uncertainty. We also measured the ratios of van der Waals atom-surface interaction strengths ($C_3$ values) for Na, K, and Rb with 3\% uncertainty. Many sources of systematic uncertainty such as atomic velocity or surface geometry are common-mode and cancel out when reporting these ratios. Our measurements with a multi-species atom interferometer therefore serve as improved tests of atomic structure calculations.