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 Bdc 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 Bdc 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 Bdc distribution. This indicates inhomogeneous dephasing due to C-field gradients, which also results in spatial variation of the T2 time for the clock transition.