Observation of quantum diffractive collisions using shallow atomictraps

Monday, May 11, 2009 (All day)
Dr. Kirk Madison

We discuss measurements and calculations of the trap loss rate for laser cooled 87Rb atoms confined in either a magneto-optic or a magnetic quadrupole trap when exposed to a room temperature background gas of Ar. We study the loss rate as a function of trap depth and find that copious glancing collisions, which occur in the so-called quantum-diffractive regime and impart very little energy to the trapped atoms, result in significant differences in the loss rate for the MOT compared to a pure magnetic trap due solely to the difference in potential depth.  This finding highlights the importance of knowing the trap depth when attempting to infer the total collision cross section from measurements of atom trap loss rates.  More than just a nuisance, this variation with trap depth can be used to extract information about the differential cross section from measurements of trap loss rates.