Figure 1

Schematic diagram of energy levels for molecules and atoms. The diabatic energy levels are shown as dashed lines. The adiabatic curves (solid lines) include the atom-molecule coupling. When the magnetic field is swept from positive to negative scattering length, dissociated molecules end up in one or several atomic states, depending on the ramp rate of the magnetic field. The spheres represent the distribution of the population before and after the ramp.Reuse & Permissions

Figure 2

Dissociation energy of molecules as a function of magnetic field ramp rate. The dashed line represents the linear relation described in Ref. 16, the solid line shows the result of our model using a theoretical value for $\Delta B=0.98\mathrm{G}$ and $a_{\mathrm{bg}}=3.4\mathrm{nm}$, and the dotted line shows a curve with the product $a_{\mathrm{bg}}\Delta B$ as a fitting parameter.Reuse & Permissions

Figure 3

Temperature of the molecular cloud. After 15 ms, the temperature saturates at $\sim 250\mathrm{nK}$. Error bars represent the statistical error (standard deviation). The inset shows finer resolution data for holding times up to 6 ms. The solid line is a guide to the eye.Reuse & Permissions

Figure 4

Decay of ultracold molecules trapped alone (a) or together with atoms (b). The solid lines in (a) and (b) are fits of Eqs. (9, 10) to data, which assume vibrational relaxation in the collision of m olecules (a) or collisions between molecules and atoms (b). The insets illustrate the experimental sequences.Reuse & Permissions

Figure 5

Conversion of atoms to molecules for various ramp times. During a given time, the magnetic field was swept by 10 G. (a) and (b) show absorption images taken after 14 ms time of flight. The molecules (bottom) were radially separated from the atoms (top) by a field gradient of $2.8\mathrm{G}/\mathrm{cm}$. The molecules were converted back to atoms only 0.5 ms before imaging by ramping the magnetic field back across the Feshbach resonance. This time was chosen to be long enough for any transient field fluctuations to damp out, but short enough such that the size of the imaged cloud reflected the molecular temperature, not the dissociation energy. (a) The atoms remained in the trap. (b) The atoms were removed by a resonant laser pulse immediately after the magnetic field ramp. (c) Number of molecules as a function of ramp time for (a) (open circles) and (b) (closed circles).Reuse & Permissions