2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/28578The particle distribution in a Bose condensate under the trapping potential and its time evolution after switching off the trapping potential suddenly are calculated. We investigate the problem from the viewpoint of quantum field theory,using a model of self-interacting neutral boson field. Within the approximation of retainng the most dominant term in the Hamiltonian after applying the Bogoliubov replacement, we can calculate analytically the particle distribution as a function of space and time coordinates.4 pages, LaTeXCondensed Mattertext