Spatially resolved measurement of relaxation times in a microfabricated vapor cell

We present a new characterisation technique for atomic vapor cells, combining time-domain measurements with absorption imaging to obtain spatially resolved information on decay times, atomic diffusion and coherent dynamics. The technique is used to characterise a microfabricated Rb vapor cell, with N₂ buffer gas, placed inside a microwave cavity. High-resolution images of the population (T₁) and coherence (T₂) lifetimes in the cell are presented. Atom-wall collisions and atomic diffusion result in a `skin´ of reduced T₁ and T₂ times around the edge of the cell. The technique also allows polarisation-resolved imaging of the microwave magnetic field inside the cell. Our technique is useful for vapor cell characterisation in atomic clocks, atomic sensors, and quantum information experiments.