Physical Review A
Asymptotic formula for the condensate wave function of a trapped Bose gas
Dionisios Margetis
Abstract
An analytical property is pointed out for the universal differential equation first derived by Dalfovo, Pitaevskii, and Stringari for the condensate wave function at the boundary of a trapped Bose gas. Specifically, the constant multiplying the Airy function of the solution asymptotically outside the trap is $\sqrt{2}.$ Accordingly, the Wentzel-Kramers-Brillouin approximation is determined in the case of a spherically symmetric harmonic potential. This calculation is related to Josephson-type currents flowing between well-separated traps.