Large atom-density change at constant temperature by varying trap anisotropy in a dilute magneto-optical trap

We show that it is possible to vary the number density of a trapped sample of laser-cooled atoms in a dilute magneto-optical trap by over an order of magnitude while keeping the temperature constant. This can be accomplished by varying the relative intensity of the trapping laser beams, such that the total intensity (sum of all six beams) remains fixed. This makes the trap anisotropic, i.e., causes the shape of the cloud to be deformed, but leaves the total number N of trapped atoms unchanged, thus leading to a change in the number density. The temperature does not change because the total laser intensity, the laser detuning, and all other trap parameters stay fixed throughout the experiment.