Figure 1

(Color online) The metastable Bose-Einstein condensate. (a) Atoms are transferred from an optically plugged trap (potential $V1$) into a purely linear trap (potential $V2$) by slowly reducing the plug intensity to zero. (b) The transfer of purely thermal atoms cooled to a final rf value of $0.35\mathrm{MHz}$, and (c) the transfer of Bose-Einstein condensates at $0.25\mathrm{MHz}$ rf. Each image was taken along the $\widehat{z}$ axis after $20\mathrm{ms}$ TOF, and is $\mathrm{1.6}\times 1.6\mathrm{mm}$. Below each image is a slice through the data as well as a fit to the thermal wings (dashed lines). (d) The view perpendicular to the $\widehat{z}$ axis shows anisotropic expansion of the BEC after $15\mathrm{ms}$ TOF. The image is $0.5\times 0.7\mathrm{mm}$.Reuse & Permissions

Figure 2

(Color online) The decay in the linear trap. (a) The condensate number is plotted against hold time for traps with axial magnetic field gradients of $21\mathrm{G}∕\mathrm{cm}$ (filled circles) and $13\mathrm{G}∕\mathrm{cm}$ (open circles). (b) The decay of purely thermal clouds with field gradients of $21\mathrm{G}∕\mathrm{cm}$ (open circles) and $105\mathrm{G}∕\mathrm{cm}$ (filled circles), corresponding to measured temperatures of $2.7\mu \mathrm{K}$ and $8.2\mu \mathrm{K}$, respectively. The solid lines are fits to a single exponential, as described in the text.Reuse & Permissions

Figure 3

(Color online) The ring-shaped expansion of a BEC. (a) The images of a condensate after various hold times (given below each image) and times of flight (given above). (b) The slice through the data at $30\mathrm{ms}$ TOF shows a high-contrast density minimum on top of the thermal background. (c) The radius of the central hole (filled squares) and the condensate (open circles) vs time of flight. The velocities of expansion are $14\mathrm{mm}∕\mathrm{s}$ and $3.5\mathrm{mm}∕\mathrm{s}$, respectively.Reuse & Permissions