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Stable periodic density waves in dipolar Bose-Einstein condensates trapped in optical lattices


  Aleksandra Maluckov [1]  ,  Goran Gligorić [2]  ,  Lj. Hadžievski [3]  ,  Boris A. Malomed [4]  ,  Tilman Pfau [5]  
 [1] Faculty of Sciences and Mathematics, University of Niš, P. O. B. 224, 18000 Niš, Serbia
[2] Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, D-01187 Dresden, Germany
[3] Vinča Institute of Nuclear Sciences, University of Belgrade, P. O. B. 522,11001 Belgrade, Serbia
[4] Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
[5] Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany

Density-wave patterns in dipolar Bose-Einstein condensates (BECs), loaded into a deep one-dimensional (1D) optical lattice (OL), are investigated my means of analytical and numerical methods in the tight-binding (discrete) limit. Patterns featuring multiple periodicities, with respect to the period of the underlying OL, can be generated by the modulational instability (MI) of the continuous-wave (CW) state, whose period is identical to that of the OL. We conclude that stable double- and triple- period patterns (DPPs and TPPs) exist, provided that the dipole-dipole (DD) interactions are repulsive and sufficiently strong, in comparison with the local repulsive nonlinearity. Unlike the DPPs, whose stability region is relatively narrow with respect to the DD interaction strength, a vast stability region for the TPPs is identified in the systems' parameter space.