TY - JOUR T1 - Number Fluctuations and Energy Dissipation in Sodium Spinor Condensates JF - Physical Review Letters Y1 - 2009 A1 - Yingmei Liu A1 - Eduardo Gomez A1 - Stephen E. Maxwell A1 - Lincoln D. Turner A1 - Eite Tiesinga A1 - Paul D. Lett AB - We characterize fluctuations in atom number and spin populations in F=1 sodium spinor condensates. We find that the fluctuations enable a quantitative measure of energy dissipation in the condensate. The time evolution of the population fluctuations shows a maximum. We interpret this as evidence of a dissipation-driven separatrix crossing in phase space. For a given initial state, the critical time to the separatrix crossing is found to depend exponentially on the magnetic field and linearly on condensate density. This crossing is confirmed by tracking the energy of the spinor condensate as well as by Faraday rotation spectroscopy. We also introduce a phenomenological model that describes the observed dissipation with a single coefficient. VL - 102 UR - http://arxiv.org/abs/0906.2110v1 CP - 22 J1 - Phys. Rev. Lett. U5 - 10.1103/PhysRevLett.102.225301 ER -