Seminars of the Focus Area Complex Systems

Prof. Dr. C. Beta, Prof. Dr. K. Dethloff, Prof. Dr. R. Engbert, Prof. Dr. M. Holschneider, Prof. Dr. W. Huisinga, Prof. Dr. Ralf Metzler, Prof. Dr. A. Pikovsky, Prof. Dr. S. Reich, Prof. Dr. M. Rosenblum, Prof. Dr. G. Rüdiger, Prof. Dr. T. Scheffer, Prof. Dr. F. Scherbaum, Prof. Dr. J. Selbig, Prof. Dr. F. Spahn


Speaker: A.P. Itin, Space Research Institute, Moscow

Title: Dynamics of ultracold atoms in driven optical lattices: applying methods of classical Hamiltonian systems with slow/fast variables

Time: Wed, Mar 19, 2014, 3:15pm

Place: bldg 28, room 0.102

Ultracold atoms in optical lattices were recently used for quantum simulation of solid-state phenomena [1,2]. I present here analysis of several systems related to driven optical lattices. Firstlly, a general problem of directed transport in a fastly driven classical periodic potential is considered [3]. Using canonical perturbation theory, general expressions are derived for the drift velocity in an arbitrary potential and uniform force. Secondly, quantum systems are considered: Bose- and Fermi-Hubbard models in the presence of high-frequency driving [4,5]. While it is well-known that a high-frequency force renormalizes hopping parameters of these models, corrections due to interactions and external potentials were not known before. A method inspired by classical canonical perturbation theory is used to derive effective Hamiltonians of these systems. The presented method has cetain advantages to recent studies based on flow equation method [4].

I analyze then recent Hamburg experiments with ultracold atoms in amplitude-modulated optical lattices [1], which build quantum simulator of the phenomenon of photoconductivity, and with bosons in shaken lattices [2]. In the former experiment, fermionic atoms in optical lattices were used to simulate the phenomenon of photoconductivity. Amplitude modulation of the optical lattice induces the analog of a persistent alternating photocurrent in the atomic gas. The dynamics can be analyzed quantitatively by a semiclassical method based on Truncated Wigner Approximation. In the experiment with shaken lattices [2], high-frequency driving of the lattice creates an effective artificial gauge field. One can draw an analogy to the directed transport in driven classical periodic potential. If time allows, dynamics of quantum phase transition in Dicke models with slowly changing parameters [7] will be considered.

[1] J.Heinze, J.S.Krauser, N.Fläschner, B.Hundt, S.Götze, A.P.Itin,, Phys. Rev. Lett. 110 (2013) [2] J.Struck, Phys. Rev. Lett. 108, 225304 (2012). [3] A.P.Itin, A.I.Neishtadt, Phys.Rev.E 86, 016206 (2012). [4] A.P.Itin, A.I. Neishtadt, Phys.Lett.A 378, 822 (2014) [5] A.P.Itin, arxiv:1401.0402 (2014). [6] A. Verdeny et. al., Phys. Rev. Lett. 111, 175301 (2013). [7] A.P.Itin and P.Törmä, Phys. Rev. A 79, 055602 (2009)/arXiv:0901.4778.

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Udo Schwarz, Zentrum für Dynamik komplexer Systeme,
Universität Potsdam, Campus Golm Karl-Liebknecht-Str. 24, 14476 Potsdam, building 28, room 2.107
Phone: (+49-331) 977-1658, Fax : (+49-331) 977-1045

Email: Udo.Schwarz AT

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