Quantum corrections to the groundstate energy of a trapped BoseEinstein condensate: A diffusion Monte Carlo calculation
Abstract
The diffusion Monte Carlo method is applied to describe a trapped atomic BoseEinstein condensate at zero temperature, fully quantum mechanically and nonperturbatively. For low densities, n(0)a^{3}<=2×10^{3} [n(0), peak density; a, swave scattering length], our calculations confirm that the exact groundstate energy for a sum of twobody interactions depends to a good approximation on only the atomicphysics parameter a, and no other details of the twobody model potential. Corrections to the meanfield GrossPitaevskii energy range from being essentially negligible to about 20% for N=250 particles in the trap with positive swave scattering length a=10010 000 a.u. Our numerical calculations confirm that inclusion of an additional effective potential term in the meanfield equation, which accounts for quantum fluctuations [see, e.g., E. Braaten and A. Nieto, Phys. Rev. B 56, 14 745 (1997)], leads to a greatly improved description of trapped Bose gases.
 Publication:

Physical Review A
 Pub Date:
 June 2001
 DOI:
 10.1103/PhysRevA.63.063601
 arXiv:
 arXiv:condmat/0009220
 Bibcode:
 2001PhRvA..63f3601B
 Keywords:

 03.75.Fi;
 02.70.Rr;
 05.30.Jp;
 General statistical methods;
 Boson systems;
 Condensed Matter
 EPrint:
 7 pages, 4 figures