Inelastic Atom–Atom Collisions in an External Electromagnetic Field: Cooling of Dense Atomic Gases

Abstract

Inelastic atom-atom collisions accompanied by absorption or emission of photons of the applied electromagnetic field are discussed. It is shown that depending on the sign (positive or negative) of the detuning between the atomic frequency and the frequency of the electromagnetic field, the system can be cooled down or heated up. The equations describing the cooling rate of atoms are derived and analyzed. It is shown that the atoms' statistics plays a crucial role in the discussed processes. Particularly, the cooling (heating) rate of the system of Bose atoms decreases with the decrease of the temperature, whereas under some conditions, the cooling (heating) rate of the system of Fermi atoms increases with the decrease of the temperature. Various scenarios due to different possible numerical ratios between the atoms' system and electromagnetic field parameters are discussed.