Coherent spin mixing dynamics in a spin-1 atomic condensate
  We study the coherent off-equilibrium spin mixing inside an atomic condensate. Using mean field theory and adopting the single spatial mode approximation (SMA), the condensate spin dynamics is found to be well described by that of a nonrigid pendulum, and displays a variety of periodic oscillations in an external magnetic field. Our results illuminate several recent experimental observations and provide critical insights into the observation of coherent interaction-driven oscillations in a spin-1 condensate. 
Wenxian Zhang, D. L. Zhou, M. -S. Chang, M. S. Chapman, and L. You