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Above threshold scattering about a Feshbach resonance for ultracold atoms in an optical collider



Eite Tiesinga, Milena S. Horvath, Ryan Thomas, Amita B. Deb, Niels Kjaergaard


Studies of magnetically tunable Feshbach resonances in ultracold atomic gases have predominantly been car- ried out in the zero collision-energy limit. Here, we explore above threshold collisions at well-defined energies in the vicinity of a narrow magnetic Feshbach resonance by means of a laser-based collider. Our experiment focuses on collisions between ground-state 87Rb atoms in the |F = 2,mF = 0⟩ and |F = 1,mF = 1⟩ hyperfine states, which have a known s-wave resonance at 9.040(7) G at threshold that strongly couples to inelastic chan- nels, where 1 G = 10−4 T. Using our collider we can track the magnetic field shift in resonance position as the energy is tuned. This presents a challenge due to the narrow width of the resonance in conjunction with inherent broadening mechanisms of the collider. We find, however, that the narrow Feshbach scattering feature becomes imprinted on the spatial distribution of atoms in a fashion that allows for an accurate determination of resonance position as a function of collision energy through a shift in center-of- mass position of the outgoing clouds. This shift has a dispersive line shape with a zero value at the resonance position. We obtain excellent agreement with theory on the resonance position.
Nature Communications


ultracold atoms, feshbach resonances, optical collider


Tiesinga, E. , Horvath, M. , Thomas, R. , Deb, A. and Kjaergaard, N. (2017), Above threshold scattering about a Feshbach resonance for ultracold atoms in an optical collider, Nature Communications, [online], (Accessed April 15, 2024)
Created September 6, 2017, Updated November 10, 2018