Spin evolution in ultracold quantum gases

We discuss the static and dynamic magnetic properties of cold quantum gas systems. In particular, we investigate and analyze the ground state properties and dynamics of F = 2 spinor Bose-Einstein condensates of ⁸⁷Rb. The rich physics of these systems is governed by an interplay between mean-field-driven spin dynamics and hyperfine-changing losses in addition to interactions with atoms in the thermal cloud. We find conversion rates on the order of 10^-12 cm³ s^-1 for spin-changing collisions within the F = 2 manifold and spin-dependent loss rates on the order of 10^-13 cm³ s^-1 for hyperfine-changing collisions. Our data leads to the conclusion that the F = 2 ground state of ⁸⁷Rb is polar, while we measure the F = 1 ground state to be ferromagnetic. As remarkable features in the spin dynamics we observe spinor oscillations and a delayed formation of new m_F-condensate components.