Condensed Matter Physics, 2019, vol. 22, No. 1, 13001
DOI:10.5488/CMP.22.13001           arXiv:1903.11457

Title: On the finite-size effects in two segregated Bose-Einstein condensates restricted by a hard wall
Author(s):
  H.V. Quyet (Department of Physics, Hanoi Pedagogical University 2, Hanoi, Vietnam) ,
  N.V. Thu (Department of Physics, Hanoi Pedagogical University 2, Hanoi, Vietnam) ,
  D.T. Tam (Tay Bac University, Son La, Vietnam) ,
  T.H. Phat (Vietnam Atomic Energy Commission, 59 Ly Thuong Kiet, Hanoi, Vietnam)

The finite-size effects in two segregated Bose-Einstein condensates (BECs) restricted by a hard wall is studied by means of the Gross-Pitaevskii equations in the double-parabola approximation (DPA). Starting from the consistency between the boundary conditions (BCs) imposed on condensates in confined geometry and in the full space, we find all possible BCs together with the corresponding condensate profiles and interface tensions. We discover two finite-size effects: a) The ground state derived from the Neumann BC is stable whereas the ground states derived from the Robin and Dirichlet BCs are unstable. b) Thereby, there equally manifest two possible wetting phase transitions originating from two unstable states. However, the one associated with the Robin BC is more favourable because it corresponds to a smaller interface tension.

Key words: finite-size effect, Bose-Einstein condensates, boundary condition, double-parabola approximation
PACS: 03.75.Hh, 05.30.Jp, 68.03.Cd, 68.08.Bc


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