Competition between attractive and repulsive interactions in two-component Bose-Einstein condensates trapped in an optical lattice
- Institute of Theoretical Physics, Physics Department, Warsaw University, Hoza 69, PL-00-681 Warsaw (Poland)
- Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)
We consider effects of interspecies attraction on two-component gap solitons (GSs) in the binary BEC with intraspecies repulsion, trapped in the one-dimensional optical lattice (OL). Systematic simulations of the coupled Gross-Pitaevskii equations corroborate an assumption that, because the effective mass of GSs is negative, the interspecies attraction may split the two-component soliton. Two critical values, {kappa}{sub 1} and {kappa}{sub 2}, of the OL strength ({kappa}) are identified. Two-species GSs with fully overlapping wave functions are stable in strong lattices ({kappa}>{kappa}{sub 1}). In an intermediate region, {kappa}{sub 1}>{kappa}>{kappa}{sub 2}, the soliton splits into a double-humped state with separated components. Finally, in weak lattices ({kappa}<{kappa}{sub 2}), the splitting generates a pair of freely moving single-species GSs. We present and explain the dependence of {kappa}{sub 1} and {kappa}{sub 2} on the number of atoms (total norm), and on the relative strength of the competing interspecies attraction and intraspecies repulsion. The splitting of asymmetric solitons, with unequal norms of the two species, is briefly considered too. It is found and explained that the splitting threshold grows with the increase of the asymmetry.
- OSTI ID:
- 21020821
- Journal Information:
- Physical Review. A, Vol. 76, Issue 4; Other Information: DOI: 10.1103/PhysRevA.76.043826; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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