@article {1839, title = {Beyond the spin model approximation for Ramsey spectroscopy}, journal = {Phys. Rev. Lett.}, volume = {112}, year = {2014}, pages = {123001}, url = {http://link.aps.org/doi/10.1103/PhysRevLett.112.123001}, author = {A P Koller and M Beverland and Alexey V. Gorshkov and A M Rey} }