A quantum phase transition in the bose-einstein condensates

Quantum phase transition and dynamical stability in Bose-Einstein condensates (BECs) are studied within the framework of the Cornwall-Jackiw-Tomboulis (CJT) effective action approach. The effective potential is found in the double-bubble diagram approximation. Numerical results show that in this approximation stability is strongly influenced by the chemical potential and the quantum phase transition is of second order.