Figure 1

Magnetic field ramp sequence for producing molecules and measuring their decay rate. The Feshbach resonance is indicated by the dashed line. The field is first swept as quickly as possible from the evaporation field to the opposite side of the resonance. A second ramp back across the resonance converts some atoms to molecules. The molecules are then held at a constant field above the resonance for a variable amount of time. A third ramp across the resonance then converts any remaining molecules back into atoms and the magnetic trap is turned off.Reuse & Permissions

Figure 2

Measurements of molecular lifetime. (a) Number of atoms remaining after holding the system at 156.6 G as a function of the hold time. The decay fits nicely to an exponential and from this we get a lifetime of 10.4(1.7) ms. The error represents the statistical error from the exponential fit to the data. The baseline indicates we have converted 30% of the atoms into molecules. (b) Number of atoms remaining after holding at 155.5 G as a function of the hold time. In this case atoms are being lost from the trap during the hold time due to three-body collisions and we never observe a horizontal baseline. Analyzing the data taking into account this atom loss we get a molecule lifetime of 24.7(6.4) ms.Reuse & Permissions

Figure 3

Molecule lifetime as a function of magnetic field. The experimental data are represented by the closed points. The two lines are the results of theoretical calculations with no free parameters by Köhler et al. (Ref. 19) in which molecules spontaneously decay due to inelastic spin relaxation. The solid line arises from an exact coupled channels scattering calculation. The dashed line results from a simpler calculation in which the detailed nature of the interatomic potentials is ignored, resulting in an analytic solution for the molecular lifetime. The inset shows the discrepancy between experiment and theory close to the 155.04 G Feshbach resonance.Reuse & Permissions