Feshbach resonances and the asymptotic bound state model

S. J. J. M. F. Kokkelmans

Shina Tan

Jason A. Young, Clifford M. Surko

M. R. Goosen, T. G. Tiecke, Jook T. M. Walraven +5 more

eshbach resonances play a central role in the manipulation of the interparticle interaction in ultracold atomic gases. The Asymptotic Bound-state Model (ABM) [1,2] is a powerful and easy-to-use tool to predict properties of these Feshbach resonances. This model exploits the fact that only the least bound states in the interaction potential determine the low energy interaction properties. These bound states are coupled by hyperfine and Zeeman interactions, and the intersection of these coupled bound states with the scattering threshold determine the position of these Feshbach resonances. The high accuracy of this model was clearly demonstrated when assigning 13 resonances in the 6Li-40K mixture by using only two bound state parameters [1]. Here we discuss the extension of the ABM by the including threshold effects, which allow for the prediction of the resonance width as well.

M. R. Goosen, Sjjmf Servaas Kokkelmans

We present an Asymptotic Bound state Model (ABM), which is useful to predict Feshbach resonances. The model utilizes asymptotic properties of the interaction potentials to represent coupled molecular wavefunctions. The bound states of this system give rise to Feshbach resonances, localized at the magnetic fields of intersection of these bound states with the scattering threshold. This model was very successful to assign measured Feshbach resonances in an ultra cold mixture of ^6Li and ^40K atomsootnotetextE. Wille, F.M. Spiegelhalder, G. Kerner, D. Naik, A. Trenkwalder, G. Hendl, F. Schreck, R. Grimm, T.G. Tiecke, J.T.M. Walraven, S.J.J.M.F. Kokkelmans, E. Tiesinga, P.S. Julienne, arXiv:0711.2916. For this system, the accuracy of the determined scattering lengths is comparable to full coupled channels results. However, it was not possible to predict the width of the resonances. We discuss how an incorporation of threshold effects will improve the model, and we apply it to a mixture of ^87Rb and ^133Cs atoms, where recently Feshbach resonances have been measured.

Raffaele Carlone, M. Correggi, D. Finco +1 more