Ultracold quantum gases in one - dimensional optical lattice potentials – nonlinear matter wave dynamics –

We investigate experimentally and theoretically the nonlinear propagation of Rb Bose Einstein condensates in a trap with cylindrical symmetry. An additional weak periodic potential which encloses an angle with the symmetry axis of the waveguide is applied. The observed complex wave packet dynamics results from the coupling of transverse and longitudinal motion. We show that the experimental observations can be understood applying the concept of effective mass, which also allows to model numerically the three dimensional problem with a one dimensional equation. Within this framework the observed slowly spreading wave packets are a consequence of the continuous change of dispersion. The observed splitting of wave packets is very well described by the developed model and results from the nonlinear effect of transient solitonic propagation. OCIS codes: (270.5530) Pulse propagation and solitons; (020.0020) Atomic and molecular physics; (350.4990) Particles References and links 1. “Bose-Einstein condensation in atomic gases,” ed. by M. Inguscio, S. Stringari, and C. Wieman, (IOS Press, Amsterdam 1999) 2. F.S. Cataliotti, S. Burger, S. C. Fort, P. Maddaloni, F. Minardi, A. Trombettoni, A. Smerzi, and M. Ingusio, “Josephson Junction Arrays with Bose-Einstein Condensates”, Science 293 843 (2001). 3. A. Trombettoni and A. Smerzi, “Discrete Solitons and Breathers with Dilute Bose-Einstein Condensates,” Phys. Rev. Lett. 86 2353 (2001). 4. M. Steel and W. Zhang, “Bloch function description of a Bose-Einstein condensate in a finite optical lattice,” cond-mat/9810284 (1998). 5. P. Meystre, Atom Optics (Springer Verlag, New York, 2001) p 205, and references therein. 6. The experimental realization in our group will be published elsewhere. 7. V.V. Konotop, M. Salerno, “Modulational instability in Bose-Einstein condensates in optical lattices,” Phys. Rev. A 65 021602 (2002). 8. N. Ashcroft and N. Mermin, Solid State Physics (Saunders, Philadelphia, 1976). 9. A.A. Sukhorukov, D. Neshev, W. Krolikowski, and Y.S. Kivshar, “Nonlinear Bloch-wave interaction and Bragg scattering in optically-induced lattices,” nlin.PS/0309075. 10. B. Eiermann, P. Treutlein, Th. Anker, M. Albiez, M. Taglieber, K.-P. Marzlin, and M.K. Oberthaler, “Dispersion Management for Atomic Matter Waves,” Phys. Rev. Lett. 91 060402 (2003). 11. M. Kozuma, L. Deng, E.W. Hagley, J. Wen, R. Lutwak, K. Helmerson, S.L. Rolston, and W.D. Phillips, “Coherent Splitting of Bose-Einstein Condensed Atoms with Optically Induced Bragg Diffraction,” Phys. Rev. Lett. 82 871 (1999).