Transit time corrections to the diffusion of atomic lattices

We present transit time corrections for the diffusive decay of an atomic ground-state population grating formed by spatially periodic optical pumping. We present results corresponding to two configurations, the first of which involves a population grating with a Gaussian envelope that is weakly probed using coherent scattering by a laser beam with a Gaussian spatial profile. The second configuration involves a population grating with a rectangular envelope that is weakly probed using coherent scattering by a laser beam with an idealized rectangular spatial profile of the same size. Recently, these corrections have been used to quantify systematic effects in measurements of Rb-inert gas diffusion coefficients near room temperature. Rubidium diffusion can be used to realize a quantum pressure sensor.