Characterization of a Static Magnetic Field with Two-Photon Rotational Spectroscopy of Cold Trapped HD+

Two-photon rotational spectroscopy of cold trapped HD⁺ ions may be exploited for characterization of the magnitude and orientation of a static magnetic field in the ion trap. The experimental setup and the approach for calibration of the magnetic field vector are described. A sensitivity at the 10^-11 T level may be reached with Zeeman spectroscopy of a hyperfine component of the (v,L) = (0,0)→(0,2) transition. The orientation of a magnetic field with a magnitude at the 1 μT level may be characterized with an uncertainty better than 30 mrad.