Interaction-driven Dynamics of 40K / 87Rb Fermi-Bose Gas Mixtures in the Large Particle Number Limit

摘要

We have studied effects of interspecies attraction in a Fermi-Bose mixtureover a large regime of particle numbers in the 40K / 87Rb system. We report onthe observation of a mean field driven collapse at critical particle numbers of1.2 million 87Rb atoms in the condensate and 750,000 40K atoms consistent withmean field theory for an interspecies scattering length of -281(15) Bohr radii[S. Inouye et al., Phys. Rev. Lett. 93, 183201 (2004)]. For overcriticalparticle numbers, we see evidence for revivals of the collapse. Before andafter the collapse, the axial expansion profileof the 40K cloud is stronglymodified and reflects the in-trap density profile distorted by the mean fieldinterspecies attraction. Part of our detailed study of the decay dynamics andmechanisms is a measurement of the (87Rb - 87Rb- 40K) three-body losscoefficient K3=(2.8+-1.1)*10^-28 cm^6/s, which is an important input parameterfor dynamical studies of the system.