Long-time-scale dynamics of spin textures in a degenerateF=187Rb spinor Bose gas

Abstract

We investigate the long-term dynamics of spin textures prepared by cooling unmagnetized spinor gases of $F=1$ ${}^{87}$Rb to quantum degeneracy, observing domain coarsening and a strong dependence of the equilibration dynamics on the quadratic Zeeman shift $q$. For small values of $|q|$, the textures arrive at a configuration independent of the initial spin-state composition, characterized by large length-scale spin domains and the establishment of easy-axis (negative $q$) or easy-plane (positive $q$) magnetic anisotropy. For larger $|q|$, equilibration is delayed as the spin-state composition of the degenerate spinor gas remains close to its initial value. These observations support the mean-field equilibrium phase diagram predicted for a ferromagnetic spinor Bose-Einstein condensate and also illustrate that equilibration is achieved under a narrow range of experimental settings, making the $F=1$ ${}^{87}$Rb gas more suitable for studies of nonequilibrium quantum dynamics.