Longitudinal Spin Diffusion of a Two-Domain Ultracold Non-Degenerate Bose Gas

Synopsis

We explore the effects of domain wall width on a two-domain ultracold nondegenerate trapped gas of Rubidium-87. A gas of Rubidium-87 atoms is evaporatively cooled to just above quantum degeneracy. Atoms are then prepared in a configuration of two longitudinal spin domains separated by a coherent helical domain wall, and spin diffusion is observed. We demonstrate the slowing of spin wave oscillations as domain wall width is increased, as a result of increased coherent spin interactions. In the presence of a linear potential gradient, spin domains are stabilized and reach a maximum lifetime near the equilibrium domain wall width. Equilibrium domain wall widths are determined through analysis of the domain wall width relaxation rate and results show good agreement with hydrodynamic approximations of the quantum Boltzmann equation.