Sensitive spatially resolved magnetometry using a Bose-condensed gas with a bright probe

We demonstrate a sensitive spatially resolved magnetometer using a spinor Bose-Einstein condensate (BEC) of ⁸⁷Rb atoms with increased probe fluence. By performing a probe parameter search using a two-polarization phase contrast imaging technique, we find that the probe-induced atom loss, a major constraint in optical magnetometry with high-density gas, can be reduced. We attain a sensitivity of 5.4(6) mrad for the phase measurement of Larmor precession using a measurement area of 1.4×10²3.33333pt0exμm² with a probe fluence of 4.1×10⁵3.33333pt0exμm^-2. A dc magnetic field sensitivity of 5.0(4)3.33333pt0expT/√Hz is attained with a probe fluence of 3.9×10⁵4pt0exμm^-2. The results should contribute to further enhancement of the sensitivity of a BEC magnetometer.