Measurement of the forbidden tensor polarizability of Cs using an all-optical Ramsey resonance technique

We have measured the strongly suppressed electric tensor polarizability of the Cs ground state using an optical pump-probe technique in a thermal atomic beam. The result agrees with a previous measurement and confirms the long-standing discrepancy with a theoretical value. The anticipated future reduction of the total uncertainty to the 1% level makes this quantity a valuable test for atomic structure calculations involving short-range inner-atomic interactions.