Dynamic self-trapping and non-exponential tunneling in spinor gases

We utilize a quantum simulator to realize the first observations of nonexponential tunneling within a spinor system.  We examine the polarization of the induced tunneling and investigate the effect of nonlinearity upon the tunneling rate for each spin component revealing the presence of near identical nonexponential tunneling for all spin populations. In contrast to prior work studying tunneling dynamics of scalar Bose Einstein condenstates, the spin degrees of freedom in spinor gases realize a nonlinear six-state Landau-Zener model. We find that, for the parameters considered, the observed nonlinear tunneling dynamics are well described by a reduced spin-independent two-state model involving a pair of states labelled only by their momenta. Combined with our demonstration that an evolution of the spatial density profile can be used to manipulate spin dynamics, our results imply an asymmetrical coupling between the spin and spatial degrees of freedom.