Single-Mode Approximation and Dynamical Localization in a Ferromagnetic Spin-1 Condensate

Bose condensates with internal degrees of freedom offer rich quantum dynamics due to the nonlinear spin-spin interactions and the vector properties of the condensate order parameter. Recent experiments on spin-1 condensates have revealed that the internal spin-changing collisions lead to coherent spin mixing [1]. When the size of the condensate is smaller than the spin healing length, all three Zeeman components will have the same spatial wavefunction, a condition referred to as the single-mode approximation (SMA). In this case, the coherent spin mixing in a spin-1 condensate represents a nonlinear Josephson oscillator, similar to two weakly-linked superconductors. This is an ideal system for observing Shapiro levels or the dynamical localization of the spinor system. We will report the most recent progress of our experiment.\newline \newline [1] M.-S. Chang, et al., Nat. Phys., \textbf{1}, 111 (2001)