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Condensed Matter > Strongly Correlated Electrons

Title:Sudden expansion and domain-wall melting of strongly interacting bosons in two-dimensional optical lattices and on multileg ladders

Abstract: We numerically investigate the expansion of clouds of hard-core bosons in the two-dimensional square lattice using a matrix-product-state based method. This nonequilibrium set-up is induced by quenching the trapping potential to zero and our work is specifically motivated by a recent experiment with interacting bosons in an optical lattice [Ronzheimer et al., Phys. Rev. Lett. 110, 205301 (2013)]. As the anisotropy of the amplitudes $J_x$ and $J_y$ for hopping in different spatial directions is varied from the one- to the two-dimensional case, we observe a crossover from a fast ballistic expansion in the one-dimensional limit $J_x \gg J_y$ to much slower dynamics in the isotropic two-dimensional limit $J_x=J_y$. We further study the dynamics on multi-leg ladders and long cylinders. For these geometries we compare the expansion of a cloud to the melting of a domain wall, which helps us to identify several different regimes of the expansion as a function of time. By studying the dependence of expansion velocities on both the anisotropy $J_y/J_x$ and the number of legs, we observe that the expansion on two-leg ladders, while similar to the two-dimensional case, is slower than on wider ladders. We provide a qualitative explanation for this observation based on an analysis of the rung spectrum.
Comments: 16 pages, 13 figures
Subjects: Strongly Correlated Electrons (cond-mat.str-el); Quantum Gases (cond-mat.quant-gas)
Journal reference: Phys. Rev. A 92, 053629 (2015)
DOI: 10.1103/PhysRevA.92.053629
Cite as: arXiv:1509.00696 [cond-mat.str-el]
  (or arXiv:1509.00696v2 [cond-mat.str-el] for this version)

Submission history

From: Johannes Hauschild [view email]
[v1] Wed, 2 Sep 2015 13:36:34 UTC (2,413 KB)
[v2] Wed, 9 Dec 2015 14:26:19 UTC (3,145 KB)