Nonground State Condensates of Ultracold Trapped Atoms

The population dynamics of a trapped Bose-Einstein condensate, subject to the action of an oscillatory field, is studied. This field produces a modulation of the trapping potential with the frequency close to the transition frequency between the ground state and an excited energy level. Unusual critical effects are found exhibiting sharp qualitative changes in the population dynamics. An effective averaged system is constructed explicitly illustrating the occurrence of critical phenomena. The related critical indices are calculated.