Figure 2

Figure 2: The viscosity of a cold atomic Fermi gas can be determined by analyzing the gas as it expands. The top row of images shows the expansion of the gas after it is released from a nonrotating trap (the time after release is shown above). The bottom two rows show the expansion when the gas is released from a rotating trap. The rotational frequency (left axis) is given in units of the axial trap frequency. (From Ref. [8].)