Measurements of Dipole Moments for the5s5p3P1-5sns 3S1 Transitions via Autler-Townes Spectroscopy

We report on experimental measurements of the transition dipole moments(TDMs)between the intermediate state 5s5p3Pi and the triplet Rydberg series 5sns 3S1 in an ultracold strontium gas.Here n is the principal quantum number ranging from 19 to 40.The transition 5s5p 3P1-5sns 3S1 is coupled via an ultraviolet(UV)beam,inducing Autler-Townes splitting of both states.Such a splitting of the intermediate state is spectroscopically measured by using absorption imaging on a narrow transition 5s2 1S0-5s5p 3P1 in an ultracold gas of strontium atoms.The power and size of the UV beam are carefully determined,with which the TDMs are extracted from the measured Autler-Townes splitting.The experimentally obtained TDMs are compared to the calculations based on a parametric core potential,on a Coulomb potential with quantum defect,and on the open-source library Alkali Ryderg calculator,finding good agreement with the former two models and significant deviation with the latter.