Competition between attractive and repulsive interactions in two-component Bose-Einstein condensates trapped in an optical lattice

Michal Matuszewski, Boris A. Malomed, and Marek Trippenbach
Phys. Rev. A 76, 043826 – Published 18 October 2007

Abstract

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, κ1 and κ2, of the OL strength (κ) are identified. Two-species GSs with fully overlapping wave functions are stable in strong lattices (κ>κ1). In an intermediate region, κ1>κ>κ2, the soliton splits into a double-humped state with separated components. Finally, in weak lattices (κ<κ2), the splitting generates a pair of freely moving single-species GSs. We present and explain the dependence of κ1 and κ2 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.

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  • Received 13 July 2007

DOI:https://doi.org/10.1103/PhysRevA.76.043826

©2007 American Physical Society

Authors & Affiliations

Michal Matuszewski1, Boris A. Malomed2, and Marek Trippenbach1,3

  • 1Institute of Theoretical Physics, Physics Department, Warsaw University, Hoża 69, PL-00-681 Warsaw, Poland
  • 2Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
  • 3Soltan Institute for Nuclear Studies, Hoża 69, PL-00-681 Warsaw, Poland

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Issue

Vol. 76, Iss. 4 — October 2007

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