Model of a PT-symmetric Bose-Einstein condensate in a δ-function double-well potential

The observation of PT symmetry in a coupled optical waveguide system that involves a complex refractive index has been demonstrated impressively in the experiment by Ruter et al. [Nat. Phys. 6, 192 (2010)]. This is, however, only an optical analog of a quantum system, and it would be highly desirable to observe the manifestation of PT symmetry and the resulting properties also in a real, experimentally accessible, quantum system. Following a suggestion by Klaiman et al. [Phys. Rev. Lett. 101, 080402 (2008)], we investigate a PT-symmetric arrangement of a Bose-Einstein condensate in a double-well potential, where in one well cold atoms are injected while in the other particles are extracted from the condensate. We investigate, in particular, the effects of the nonlinearity in the Gross-Pitaevskii equation on the PT properties of the condensate. To study these effects we analyze a simple one-dimensional model system in which the condensate is placed into two PT-symmetric delta-function traps. The analysis will serve as a useful guide for studies of the behavior of Bose-Einstein condensates in realistic PT-symmetric double wells.