Stable three-dimensional solitons in attractive Bose-Einstein condensates loaded in an optical lattice

الأصل · EN

The existence and stability of solitons in Bose-Einstein condensates with attractive inter-atomic interactions, described by the Gross-Pitaevskii equation with a three-dimensional (3D) periodic potential, are investigated in a systematic form. We find a one-parameter family of stable 3D solitons in a certain interval of values of their norm, provided that the strength of the potential exceeds a threshold value. The minimum number of ⁷Li atoms in the stable solitons is 60, and the energy of the soliton at the stability threshold is ≈ 6 recoil energies in the lattice. The respective energy-vs.-norm diagram features two cuspidal points, resulting in a typical swallowtail pattern, which is a generic feature of 3D solitons supported by low- (2D) or fully-dimensional lattice potentials.