arXiv:0807.1691 · Physical Review A

Role of particle interactions in a many-body model of Feshbach-molecule formation in bosonic systems

Jing Li, Difa Ye, Chao Ma, Libin Fu, Jie Liu

Published Feb 24, 2009• 27 citations

Abstract

We investigate a generalized many-body model of Feshbach molecule formation that includes the atom-atom, atom-molecule, and molecule-molecule interactions. We show that the picture of two-body molecule production depicted by the Landau-Zener model is significantly altered by the particle interactions. In the adiabatic limit, we work out a formula for the ceiling of conversion efficiency when the interaction strength is larger than a critical value. In the sudden limit, we derive a closed equation for the conversion efficiency using stationary phase approximation. Our theory predicts a significant role of the particle interactions in atom-molecule conversion when the atom density is high and the Feshbach resonance width is narrow.

DOI: 10.1103/physreva.79.025602

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arXiv:0807.1691 · Physical Review A

Role of particle interactions in a many-body model of Feshbach-molecule formation in bosonic systems

Jing Li, Difa Ye, Chao Ma, Libin Fu, Jie Liu

Published Feb 24, 2009• 27 citations

arXiv HTML PDF

Abstract

DOI: 10.1103/physreva.79.025602

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We investigate magnetoassociation of ultracold fermionic Feshbach molecules in a mixture of

{}^{40}

K and

{}^{87}

Rb atoms, where we can create

{}^{40}

{}^{87}

Rb molecules with a conversion efficiency as high as 45%. In the limit of fast magnetic sweeps and small molecule fraction, we find that the time scale of molecule production is accurately predicted by a parameter-free model that uses only the atomic densities, masses, and the known Feshbach resonance parameters. We find that molecule production efficiency saturates for slower magnetic sweeps, at which point the maximum number of Feshbach molecules depends primarily on the atoms' phase-space density. At higher temperatures, our measurements agree with a phenomenological model that successfully describes the formation of bosonic molecules from either Bose or Fermi gases. However, for quantum degenerate atom gas mixtures, we measure significantly fewer molecules than this model predicts.