ZERO-TEMPERATURE PROPERTIES OF A TRAPPED BOSE-CONDENSED GAS - BEYOND THE THOMAS-FERMI APPROXIMATION

We consider the leading corrections to the Thomas-Fermi approach to th e description of the properties of a magnetically trapped, Bose-conden sed cloud of atoms. Simple analytical expressions are derived for the kinetic energy in terms of an effective cutoff length, which we calcul ate numerically by considering the one-dimensional problem for a linea r-ramp potential. We also determine the lowest angular velocity at whi ch it is energetically favorable for a vortex to enter the cloud, For large clouds, our results are in excellent agreement with available nu merical calculations.