Precision spectroscopy and density-dependent frequency shifts in ultracold Sr

Tetsuya Ido, Thomas H. Loftus, Martin M. Boyd +3

By varying the density of an ultracold ${}^{88}$Sr sample from $10^9$ cm${}^{-3}$ to $>10^{12}$ cm${}^{-3}$, we make the first definitive measurement of the density-related frequency sh…