Landé g Factor Measurement of ^{48}Ti^{+} Using Simultaneous Comagnetometry and Quantum Logic Spectroscopy.

We present a quantum logic scheme mitigating systematic effects in the measurement of magnetic properties of ions caused by temporal magnetic field fluctuations through comagnetometry. This is achieved through simultaneous interrogation of a spectroscopy ion and a cotrapped reference ion with a precisely known g factor confined in a Paul trap. This allows measurement of the ground state g factors of a single ^{48}Ti^{+} ion with uncertainties at the 10^{-6} level in the weak B-field regime. The experimental scheme can be applied to many ions, including those that cannot be directly laser cooled. We compare the experimentally determined g factors of ^{48}Ti^{+} with new theoretical predictions using a combination of configuration interaction and second-order many-body perturbation theory. Theory and experiment agree within the expected level of accuracy.