Scott Holmes, Mason A. Porter, Peter Krüger, Panayotis G. Kevrekidis
We study statically homogeneous Bose-Einstein condensates with spatially inhomogeneous interactions and outline experimental realizations of compensating linear and nonlinear potentials that can yield such constant-density solutions. We illustrate how the presence of a step in the nonlinearity coefficient can be revealed dynamically by a defect-dragging experiment due to the inhomogeneity of the sound speed. We then use effective-potential theory to perform a detailed analytical investigation of the existence and stability of solitary waves in this setting, and we corroborate these results computationally using a Bogoliubov-de Gennes linear stability analysis. We find that dark solitary waves are unstable for all step widths, whereas bright solitary waves can become stable through a symmetry-breaking bifurcation as one varies the step width. We illustrate the various scenarios that permit this bifurcation by examining the phase plane of the corresponding dynamics.
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http://arxiv.org/abs/1301.1715
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