TY - JOUR T1 - Beyond the spin model approximation for Ramsey spectroscopy JF - Phys. Rev. Lett. Y1 - 2014 A1 - A P Koller A1 - M Beverland A1 - Alexey V. Gorshkov A1 - A M Rey VL - 112 U4 - 123001 UR - http://link.aps.org/doi/10.1103/PhysRevLett.112.123001 ER -