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arXiv:cond-mat/0501095 · Physical Review A

Cross-dimensional relaxation in Bose-Fermi mixtures

J. Goldwin, S. Inouye, M. L. Olsen, D. S. Jin

Published Apr 21, 2005• 18 citations
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Abstract

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.

DOI
10.1103/physreva.71.043408

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The study of ultracold optically trapped atoms has opened new vistas in the physics of correlated quantum systems. Much attention has now turned to mixtures of bosonic and fermionic atoms. A central puzzle is the disagreement between the experimental observation of a reduced bosonic visibility Vb{\mathcal{V}}_{b}Vb​, and quantum Monte Carlo (QMC) calculations which show Vb{\mathcal{V}}_{b}Vb​ increasing. In this paper, we present QMC simulations which evaluate the density profiles and Vb{\mathcal{V}}_{b}Vb​ of mixtures of bosons and fermions in one-dimensional optical lattices. We resolve the discrepancy between theory and experiment by identifying parameter regimes where Vb{\mathcal{V}}_{b}Vb​ is reduced, and where it is increased. We present a simple qualitative picture of the different response to the fermion admixture in terms of the superfluid and Mott-insulating domains before and after the fermions are included. Finally, we show that Vb{\mathcal{V}}_{b}Vb​ exhibits kinks which are tied to the domain evolution present in the pure case, and also additional structure arising from the formation of boson-fermion molecules, a prediction for future experiments.
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