arXiv:physics/0410110 · Physical Review Letters
Precision Spectroscopy and Density-Dependent Frequency Shifts in Ultracold Sr
T. Ido, Thomas H. Loftus, Martin M. Boyd, Andrew D. Ludlow, Kevin W. Holman, Jun Ye
Abstract
By varying the density of an ultracold $^{88}\mathrm{Sr}$ sample from ${10}^{9}$ to$>{10}^{12}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}3}$, we make the first definitive measurement of the density-related frequency shift and linewidth broadening of the $^{1}S_{0}\mathrm{\text{\ensuremath{-}}}^{3}P_{1}$ optical clock transition in an alkaline earth system. In addition, we report the most accurate measurement to date of the $^{88}\mathrm{Sr}$ $^{1}S_{0}\mathrm{\text{\ensuremath{-}}}^{3}P_{1}$ optical clock transition frequency. Including a detailed analysis of systematic errors, the frequency is $[434\text{ }\text{ }829\text{ }\text{ }121\text{ }\text{ }312\text{ }\text{ }334\ifmmode\pm\else\textpm\fi{}20(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}33(\mathrm{syst})]\text{ }\text{ }\mathrm{Hz}$.