Real-time vector field tracking with a cold-atom magnetometer

We demonstrate a fast three-axis optical magnetometer using cold, optically trapped Rb-87 gas as a sensor. By near-resonant Faraday rotation we record the free-induction decay of a spin polarized ensemble following optical to obtain the three field components and one gradient component. A single measurement achieves shot-noise limited sub-nT sensitivity in 1 ms, with transverse spatial resolution of similar to 20 mu m. We make a detailed analysis of the shot-noise-limited sensitivity. (C) 2013 AIP Publishing LLC.