## SCL Seminar by Tao Wang

Tao Wang (Department of Physics, Harbin Institute of Technology, China and Department of Physics, Technical University of Kaiserslautern, Germany) presented a seminar:

**"Artificially Tuned Optical Lattices"**

**Abstract:**In this talk we will focus on two types of artificially tuned optical lattices, namely superlattices and periodically driven optical lattice systems. At first, in view of a superlattice system, we will report on a generalization of the Effective Potential Landau Theory (EPLT) for a single component [1] to multi-component case [2]. In particular, we will suggest how to experimentally realize a Kagome superlattice system where an anisotropic superfluidity should emerge due to two faces of an interaction blockade. Afterwards, we will discuss in detail an optical lattice system, where the s-wave scattering length is modulated periodically [3]. Motivated by the Floquet theory [4], we will show that for large enough driving frequencies the original time-dependent Bose-Hubbard Hamiltonian is well approximated by an effective time-independent Bose-Hubbard model. We can even conclude that the driven many-body system must have the same critical exponents as the much simpler non-driven lattice system provided that the driving amplitude is not too large. Finally, we will present initial results of calculation of the ground-state energy of the Bose-Hubbard model to high orders by invoking the process-chain approach [5]. In the outlook we will discuss the prospects of using the process-chain approach for analyzing artificially tuned optical lattices.

[1] F. E. A. Santos and A. Pelster, Phys. Rev. A 79, 013614 (2009)

[2] T. Wang, X.-F. Zhang, S. Eggert, and A. Pelster, Phys. Rev. A 87, 063615 (2013)

[3] A. Rapp, X. Deng, and L. Santos, Phys. Rev. Lett. 109, 203005 (2012)

[4] E. Arimondo, D. Ciampini, A. Eckardt, M. Holthaus, and O. Morsch, Adv. At. Mol. Opt. Phys. 61, 515 (2012)

[5] N. Teichmann, D. Hinrichs, M. Holthaus, and A. Eckardt, Phys. Rev. B 79, 224515 (2009)