Direct, Non-Destructive Imaging of Magnetization in a Spin-1 Bose Gas
  Polarization-dependent phase-contrast imaging is used to spatially resolve the magnetization of an optically trapped ultracold gas. This probe is applied to Larmor precession of degenerate and nondegenerate spin-1 $^{87}$Rb gases. Transverse magnetization of the Bose-Einstein condensate persists for the condensate lifetime, with a spatial response to magnetic field inhomogeneities consistent with a mean-field model of interactions. Rotational symmetry implies that the Larmor frequency of a spinor condensate be density-independent, and thus suitable for precise magnetometry with high spatial resolution. In comparison, the magnetization of the noncondensed gas decoheres rapidly. 
J. M. Higbie, L. E. Sadler, S. Inouye, A. P. Chikkatur, S. R. Leslie,   K. L. Moore, V. Savalli, and D. M. Stamper-Kurn