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A: Fachverband Atomphysik

A 22: Ultra-cold atoms, ions and BEC III (with Q)

A 22.5: Vortrag

Mittwoch, 25. März 2015, 12:00–12:15, M/HS1

Expansion of ultracold bosons in anisotropic two-dimensional optical lattices — •Konstantin Krutitsky¹, Friedemann Queisser², Patrick Navez³, and Ralf Schützhold¹ — ¹Fakultät für Physik, Universität Duisburg-Essen, Duisburg, Germany — ²Department of Physics, University of British Columbia, Vancouver, Canada — ³Department of Physics, University of Crete, Greece

Motivated by experiments on the expansion of ultracold ³⁹K atoms in anisotropic two-dimensional optical lattices [1], we present a systematic theory of this phenomenon. Initially, the atoms are prepared in the Mott-insulator state with one atom per lattice site in a finite spatial region determined by a harmonic trap. The expansion is initiated by switching-off the harmonic potential and decreasing the amplitude of the optical lattice. The system is described by an anisotropic Bose-Hubbard Hamiltonian with local interaction and two in general different tunneling rates J₁ and J₂. We investigate the dependence of the expansion speed on the lattice anisotropy J₁/J₂ and the effects of multiple occupancy of the lattice sites. Our method is based on the truncated system of equations for the local and nonlocal reduced density matrices which allows efficient treatment of large lattice systems not only in one dimension but also in higher dimensions [2,3].

[1] J. P. Ronzheimer et al, Phys. Rev. Lett. 110, 205301 (2013)

[2] F. Queisser, K. V. Krutitsky, P. Navez, and R. Schützhold, Phys. Rev. A 89, 033616 (2014)

[3] K. V. Krutitsky, P. Navez, F. Queisser, and R. Schützhold, EPJ Quantum Technology 1:12 (2014)