Laser pumped ⁴He magnetometer with light shift suppression

We report a laser-pumped ⁴He atomic magnetometer with light shift suppression through the atomic sensor itself. A linearly polarized light is used to optically align the ⁴He metastable atoms and we monitor the magneto-optical double resonance (MODR) signals produced by the left- and right-circularly orthogonal components. It is shown that light shift leads to the atomic alignment to orientation conversion effect, and thus, the difference between the two MODR signals. One of these two MODR signals is locked at the Larmor frequency and is used to measure the ambient magnetic field, while the differential signal is, simultaneously, fed back to suppress the light shift. The scheme could be of the advantage to the design of compact magnetometers by reducing the systematic errors due to light shift.