Ground-state energy of a homogeneous Bose-Einstein condensate beyond BogoliubovC. Weiss and A. Eckardt
Institut für Physik, Carl von Ossietzky Universität - D-26111 Oldenburg, Germany
received 12 May 2004; accepted in final form 30 July 2004
The standard calculations of the ground-state energy of a homogeneous Bose gas rely on approximations which are physically reasonable but difficult to control. Lieb and Yngvason (Phys. Rev. Lett. 80 (1998) 2504) have proved rigorously that the commonly accepted leading-order term of the ground-state energy is correct in the zero-density limit. Here, strong indications are given that also the next-to-leading term is correct. It is shown that the first terms obtained in a perturbative treatment provide contributions which are lost in the Bogoliubov approach.
03.75.Hh - Static properties of condensates; thermodynamical, statistical and structural properties.
67.40.Db - Quantum statistical theory; ground state, elementary excitations.
05.30.Jp - Boson systems.
© EDP Sciences 2004