Sudden expansion of Mott insulators in one dimension

Vidmar, L., Langer, S., McCulloch, I. P., Schneider, U., Schollwoeck, U. and Heidrich-Meisner, F. (2013) Sudden expansion of Mott insulators in one dimension. Physical Review B, 88 23: 235117.1-235117.16. doi:10.1103/PhysRevB.88.235117

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Author Vidmar, L.
Langer, S.
McCulloch, I. P.
Schneider, U.
Schollwoeck, U.
Heidrich-Meisner, F.
Title Sudden expansion of Mott insulators in one dimension
Journal name Physical Review B   Check publisher's open access policy
ISSN 1098-0121
1550-235X
Publication date 2013-12
Sub-type Article (original research)
DOI 10.1103/PhysRevB.88.235117
Open Access Status File (Publisher version)
Volume 88
Issue 23
Start page 235117.1
End page 235117.16
Total pages 16
Place of publication College Park, MD, United States
Publisher American Physical Society
Collection year 2014
Language eng
Abstract We investigate the expansion of bosons and fermions in a homogeneous lattice after a sudden removal of the trapping potential using exact numerical methods. As a main result, we show that in one dimension, both bosonic and fermionic Mott insulators expand with the same velocity, irrespective of the interaction strength, provided the expansion starts from the ground state of the trapped gas. Furthermore, their density profiles become identical during the expansion; the asymptotic density dynamics is identical to that of initially localized, noninteracting particles, and the asymptotic velocity distribution is flat. The expansion velocity for initial correlated Mott insulating states is therefore independent of the interaction strength and particle statistics. Interestingly, this nonequilibrium dynamics is sensitive to the interaction driven quantum phase transition in the Bose-Hubbard model; while being constant in the Mott phase, the expansion velocity decreases in the superfluid phase and vanishes for large systems in the noninteracting limit. These results are compared to the setup of a recent experiment [Ronzheimer et al., Phys. Rev. Lett. 110, 205301 (2013)], where the trap opening was combined with an interaction quench from infinitely strong interactions to finite values. In the latter case, the interaction quench breaks the universal dynamics in the asymptotic regime and the expansion depends on the interaction strength. We carry out an analogous analysis for a two-component Fermi gas, with similar observations. In addition, we study the effect of breaking the integrability of hard-core bosons in different ways; while the fast ballistic expansion from the ground state of Mott insulators in one dimension remains unchanged for finite interactions, we observe strong deviations from this behavior on a two-leg ladder even in the hard-core case. This change in dynamics bares similarities with the dynamics in the dimensional crossover from one to two dimensions observed in the aformentioned experimental study.
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Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2014 Collection
 
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