We consider the equilibration rate for fermions in Bose-Fermi mixtures undergoing cross-dimensional rethermalization. Classical Monte Carlo simulations of the relaxation process are performed over a wide range of parameters, focusing on the effects of the mass difference between species and the degree of initial departure from equilibrium. A simple analysis based on Enskog's equation is developed and shown to be accurate over a variety of different parameter regimes. This allows predictions for mixtures of commonly used alkali-metal atoms.We consider the equilibration rate for fermions in Bose-Fermi mixtures undergoing cross-dimensional rethermalization. Classical Monte Carlo simulations of the relaxation process are performed over a wide range of parameters, focusing on the effects of the mass difference between species and the degree of initial departure from equilibrium. A simple analysis based on Enskog's equation is developed and shown to be accurate over a variety of different parameter regimes. This allows predictions for mixtures of commonly used alkali-metal atoms.

arXiv:cond-mat/0501095Physical Review AApr 21, 200518 citations

Measurement of the interaction strength in a Bose-Fermi mixture with Rb 87 and K 40

J. Goldwin, S. Inouye, M. L. Olsen +3 more

A quantum degenerate, dilute gas mixture of bosonic and fermionic atoms was produced using $^{87}\mathrm{Rb}$ and $^{40}\mathrm{K}$ . The onset of degeneracy was confirmed by observing the spatial distribution of the gases after time-of-flight expansion. Furthermore, the magnitude of the interspecies scattering length between the doubly spin-polarized states of $^{87}\mathrm{Rb}$ and $^{40}\mathrm{K}$ , $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}$, was determined from cross-dimensional thermal relaxation. The uncertainty in this collision measurement was greatly reduced by taking the ratio of interspecies and intraspecies relaxation rates, yielding $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}=250\ifmmode\pm\else\textpm\fi{}30\phantom{\rule{0.3em}{0ex}}{a}_{0}$, which is a lower value than what was reported in [M. Modugno et al., Phys. Rev. A 68, 043626 (2003)]. Using the value for $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}$ reported here, current $T=0$ theory would predict a threshold for mechanical instability that is inconsistent with the experimentally observed onset for sudden loss of fermions in [G. Modugno et al., Science 297, 2240 (2002)].A quantum degenerate, dilute gas mixture of bosonic and fermionic atoms was produced using $^{87}\mathrm{Rb}$ and $^{40}\mathrm{K}$. The onset of degeneracy was confirmed by observing the spatial distribution of the gases after time-of-flight expansion. Furthermore, the magnitude of the interspecies scattering length between the doubly spin-polarized states of $^{87}\mathrm{Rb}$ and $^{40}\mathrm{K}$, $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}$, was determined from cross-dimensional thermal relaxation. The uncertainty in this collision measurement was greatly reduced by taking the ratio of interspecies and intraspecies relaxation rates, yielding $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}=250\ifmmode\pm\else\textpm\fi{}30\phantom{\rule{0.3em}{0ex}}{a}_{0}$, which is a lower value than what was reported in [M. Modugno et al., Phys. Rev. A 68, 043626 (2003)]. Using the value for $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}$ reported here, current $T=0$ theory would predict a threshold for mechanical instability that is inconsistent with the experimentally observed onset for sudden loss of fermions in [G. Modugno et al., Science 297, 2240 (2002)].

arXiv:cond-mat/0405419Physical Review AAug 11, 2004110 citations

Quantum Phase Transitions in a Bose-Fermi Mixture

Eric Duchon, Shizhong Zhang, S.-L. Chang +2 more

Bulletin of the American Physical SocietyMar 21, 20130 citations

A quantum degenerate, dilute gas mixture of bosonic and fermionic atoms was produced using

^{87}\mathrm{Rb}

and

^{40}\mathrm{K}

. The onset of degeneracy was confirmed by observing the spatial distribution of the gases after time-of-flight expansion. Furthermore, the magnitude of the interspecies scattering length between the doubly spin-polarized states of

^{87}\mathrm{Rb}

and

^{40}\mathrm{K}

, $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}$, was determined from cross-dimensional thermal relaxation. The uncertainty in this collision measurement was greatly reduced by taking the ratio of interspecies and intraspecies relaxation rates, yielding $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}=250\ifmmode\pm\else\textpm\fi{}30\phantom{\rule{0.3em}{0ex}}{a}_{0}$, which is a lower value than what was reported in [M. Modugno et al., Phys. Rev. A 68, 043626 (2003)]. Using the value for $\ensuremath{\mid}{a}_{\mathrm{RbK}}\ensuremath{\mid}$ reported here, current

T=0

theory would predict a threshold for mechanical instability that is inconsistent with the experimentally observed onset for sudden loss of fermions in [G. Modugno et al., Science 297, 2240 (2002)].