Optical pumping and relaxation of atomic population in assorted conditions

Precise control and knowledge over atomic dynamics is central to the advancement of quantum technology. The different experimental conditions namely, atoms in a vacuum, antirelaxation coated and buffer gas filled atomic cells provide complementary platforms for such investigations. The extent of changes in optical pumping, velocity changing collision and hyperfine changing collision rates associated with these conditions are discussed. There is a phenomenal change in the optical density by a factor of >25 times in the presence of a control field in a buffer gas environment. We found confinement induced enhanced optical pumping as the mechanism behind the observed transparency in buffer gas cell. The diffusive velocity of atoms were measured to be similar to 25 +/- 12 m s(-1) and <= 8 +/- 4 m s(-1) for antirelaxation coated and buffer gas filled cells respectively. The measurements were carried out for Rb-85 atoms in natural isotopic composition using pump-probe spectroscopy. The studies will have useful application in measurements of relaxation rates, quantum memory, quantum repeaters and atomic devices.