Imaging the static magnetic field distribution in a vapor cell atomic clock

We use a Ramsey-type interaction scheme to measure spatially-resolved images of the static magnetic field (C-field) amplitude B_dc applied across the Rb cell in the physics package of a high-performance vapor-cell atomic clock. Low field variations of <; 0.5% are found across the recorded images, and Fourier analysis of the data indicates low variations of B_dc also along the direction of laser propagation. Images of the T₂ relaxation time are obtained in a similar way, and show a distribution that correlates with the B_dc distribution. This indicates inhomogeneous dephasing due to C-field gradients, which also results in spatial variation of the T₂ time for the clock transition.