Effective Width and Expansion Energy of the Interacting Condensed 87Rb Bose Gas with Finite Size Effects

This work is devoted to study the temperature dependence of the effective width and expansion energy on the finite size and interaction effects (repulsive interactions). It is found that the effective size (r^2), and expansion energy in the radial direction Ey of a Bose gas follow a characteristic temperature dependence, i.e. (r^2), Ey proportional to (T/T0)4 if T0 T and (r^2), Ey proportional to (T/T0) if T0 T. Our results show that these two parameters increases with the number of atoms, and with increasing repulsive interaction strength at temperature less than the transition temperature, (T To ); yet it has little effect at temperatures higher than the transition temperature (T To ). The obtained results are compared with the available experimental data for 87Rb directly, full agreement is obtained.