Heidelberg 2015 – wissenschaftliches Programm

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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 Schützhold11Fakultät 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)

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