Cancellation of nonlinear Zeeman shifts with light shifts

Nonlinear Zeeman (NLZ) shifts arising from magnetic-field mixing of the two hyperfine ground states in alkali-metal atoms lead to splitting of magnetic-resonance lines. This is a major source of sensitivity degradation and the so-called “heading errors” of alkali-metal-vapor atomic magnetometers operating in the geophysical field range (B≈0.2–0.7 G). Here, it is shown theoretically and experimentally that NLZ shifts can be effectively canceled by light shifts caused by a laser field of appropriate intensity, polarization, and frequency, a technique that can be readily applied in practical situations.