Cooling of Sr to high phase-space density by laser and sympathetic cooling in isotopic mixtures

Based on an experimental study of two-body and three-body collisions in ultracold strontium samples, a novel optical-sympathetic cooling method in isotopic mixtures is demonstrated. Without evaporative cooling, a phase-space density of 6x10(-2) is obtained with a high spatial density that should allow us to overcome the difficulties encountered so far to reach quantum degeneracy for Sr atoms.