Посилання:Phonons and rotons of trapped atoms in gravitational field / D.B. Baranov V.S. Yarunin // Физика низких температур. — 2003. — Т. 29, № 6. — С. 674-677. — Бібліогр.: 7 назв. — англ.
The excitations of trapped atoms with a Bose-Einstein condensate in a trap are determined by the conservation of common phonon and roton numbers of atomic motion, and these properties depend on the presence of gravitational field.