  The Bose-Einstein condensates recently created in trapped atomic gases are
mesoscopic systems, in two senses: (a) Their size fall between macroscopic and
microscopic systems; (b) They have a quantum phase that can be manipulated in
experiments. We review the theoretical and experimental facts about trapped
atomic gases, and give examples that emphasize their mesoscopic characters. One
is the dynamics of collapse of a condensate with attractive interactions. The
other is the creation of a 1D kink soliton that can be used as a mode-locked
atom laser.
