Very high precision bound state spectroscopy near a 85 Rb Feshbach resonance
N. R. Claussen, S. J. J. M. F. Kokkelmans, S. T. Thompson, E. A. Donley, C. E. Wieman
Abstract
We precisely measured the binding energy of a molecular state near the Feshbach resonance in a
85
Rb Bose-Einstein condensate (BEC). Rapid magnetic field pulses induced coherent atom-molecule oscillations in the BEC. We measured the oscillation frequency as a function of B-field and fit the data to a coupled-channels model. Our analysis constrained the Feshbach resonance position [155.041(18) G], width [10.71(2) G], and background scattering length [-443(3) a
0
] and yielded new values for
v
DS
,
v
DT
, and
C
6
. These results improved our estimate for the stability condition of an attractive BEC. We also found evidence for a mean-field shift to the binding energy.