Collective processes in a large atomic laser cooling experiment

摘要

We introduce an hydrodynamic description of a laser cooled gas. In large traps, with as much as 10~(10) atoms, multiple scattering of light leads to a collective interaction field which can be described by a Poisson-like equation, included in our formulation. A behaviour similar to a one-component trapped plasma should then be observed. By considering equilibrium conditions we extract the theoretical atomic density profiles and, in particular, its dependence on the effective plasma frequency of the system. The model is compared with experimentally measured profiles with an extraordinary agreement, thus corroborating both the plasma nature of the dynamics in the gas as well as the validity of the hydrodynamic formulation introduced here.