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Resonant scattering of matter wave gap-solitons by optical lattice defects

By: Valeriy Brazhnyy
From: Univ. Oporto
At: Instituto de Investigação Interdisciplinar, Anfiteatro
[2011-05-12] 11:30

The physical mechanism underlying scattering properties of matter wave gap-solitons by linear optical lattice defects will be discussed. The occurrence of repeated reflection, transmission and trapping regions for increasing  strengths of an optical lattice defect are shown to be due to  impurity modes inside the defect potential with chemical potentials and numbers of atoms matching corresponding quantities  of an incoming gap-soliton. For gap-solitons with chemical potentials very close to band edges, the number of  resonances observed in the scattering coincides with  the number of bound states which can exist in the defect potential for the given defect strength.  The dependence of the positions  and widths of the transmission resonant on the incoming gap-soliton velocities are investigated by means of a defect mode analysis and effective mass theory. The comparisons  with direct integrations of the Gross-Pitaevskii equation provide a very good agreement confirming the correctness of our interpretation. The possibility of multiple resonant transmission through arrays of optical lattice defects is also demonstrated. In particular, we show that it is possible to  design the strength of the defects so to balance the velocity detunings and to allow the resonant transmission through a larger number of defects. The possibility of using these results for precise gap-soliton dynamical filters is suggested.