Single-beam three-axis atomic magnetometer

A single-beam atomic magnetometer being operated near zero-field and measuring three-axis fields simultaneously is demonstrated. We produce a rotating field on the x-0-y plane with the frequency of 90 Hz and a modulation field in the z axis at 130 Hz. The rotating field enables a nonzero z axis output when the transverse fields are zeroed using feedback systems. Based on the phase difference of π/2, x and y axes fields can be measured using one lock-in amplifier. Magnetic field sensitivities of 300 fT/Hz1∕2 in x and y axes and 3 pT/Hz1∕2 in the z axis are achieved.