High resolution magnetic vector-field imaging with cold atomic ensembles

We present a magnetic field imaging technique based on spatially resolved detection of Larmor precession. An optically trapped, elongated, and cold atomic sample of rubidium serves as magnetic field probe. We detect Larmor precession with a spatial and a temporal resolution of similar to 50 mu m and similar to 120 mu s, respectively. Projection-noise limited absorption imaging, feasible with current technologies, implies a sensitivity of similar to 10 pT/root Hz at 50 mu m resolution; addition of an optical lattice could give similar to 300 fT/root Hz sensitivity. (C) 2011 American Institute of Physics. [doi:10.1063/1.3555459]