Here, we consider atom-atom interactions. In a cold gas, for atoms confined in a magneto-optical trap, two types of interactions can be considered. First, we have the close range atom-atom collisions. Second, we have the long range interactions mediated by scattered photons. The atomic collisions play an important role in atom detrapping, in the gas thermalization during evaporative cooling, in the plasma ionization processes, and in the formation of Bose-Einstein condensates. Atom-atom collisions at very low energies have specific properties which have be studied by many authors (see for a review [1, 2]). After reviewing the basic properties of atomic collisions in the low energy limit, we discuss the Feshbach resonances, which result from the coupling with a discrete bound state. In the experiments, such resonances can be controlled by externally applied magnetic fields, and allow to control the atomic collision cross sections.
KeywordsFeshbach Resonance Resonant Scattering Atomic Cloud Laser Beam Intensity Trapping Force
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