Unshielded three-axis vector operation of a spin-exchange-relaxation-free atomic magnetometer

We describe a vector alkali-metal magnetometer that simultaneously and independently measures all three components of the magnetic field. Using a feedback system, the total field at the location of the magnetometer is kept near zero, suppressing the broadening due to spin-exchange collisions. The resonance linewidth and signal strength of the magnetometer compare favorably with two different scalar operation modes in which spin-exchange relaxation is only partially suppressed. Magnetic field sensitivity on the order of 1 pT/rootHz is demonstrated in a laboratory environment without magnetic shields. (C) 2004 American Institute of Physics.