Method for measuring the 6S1/2 ⇆ 5D3/2 magnetic-dipole-transition moment in Ba+

We propose a method for measuring the magnetic dipole (M1) transition moment of the 6S(1/2)(m = -1/2) <-> 5D(3/2)(m = -1/2) transition in single trapped Ba+ by exploiting different symmetries in the electric quadrupole (E2) and M1 couplings between the states. The technique is adapted from a previously proposed method for measuring atomic parity nonconservation in a single trapped ion [N. Fortson, Phys. Rev. Lett. 70, 2383 (1993)]. Knowledge of M1 is crucial for any parity nonconservation measurement in Ba+, as laser coupling through M1 can mimic the parity-violating signal. The magnetic moment for the transition has been calculated by atomic theory and found to be dominated by electron-electron correlation effects [B. K. Sahoo et al., Phys. Rev. A 74, 062504 (2006)]. To date the value has not been verified experimentally. This proposed measurement is therefore an essential step toward a parity nonconservation experiment in the ion that will also test current many-body theory. The technique can be adapted for similar parity nonconservation experiments using other atomic ions, where the magnetic dipole moment could present similar complications.