Freiburg 2019 – wissenschaftliches Programm

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FM: Fall Meeting

FM 66: Poster: Entanglement

FM 66.1: Poster

Mittwoch, 25. September 2019, 16:30–18:30, Tents

Macroscopic boundary effects in the one-dimensional extended Bose-Hubbard model — •Sebastian Stumper, Junichi Okamoto, and Michael Thoss — University of Freiburg, Germany

The one-dimensional extended Bose Hubbard model shows various quantum phases due to its competing interactions. For large on-site interactions, a Mott insulating (MI) phase exists, while a charge density wave (CDW) phase becomes dominant for large nearest-neighbour interactions. In between these phases a topologically non-trivial phase of a Haldane insulator (HI) appears [Phys. Rev. Lett. 97, 260401 (2006)]. Ground state properties and low energy spectra are, however, very sensitive to the treatment of boundary conditions [arXiv:1403.2315 (2014)].

We study an open chain of the extended Bose Hubbard model with different edge potentials using the density matrix renormalization group method based on matrix product states [Comput. Phys. Commun. 225, 59 (2018)]. Without edge potentials, the CDW and HI phases exhibit a non-degenerate ground state, and the order parameters change signs in the middle of the chain. This feature is robust against finite size scaling and is explained by a simple effective picture for the low energy states. On the other hand, with large edge potentials, the sign change of the order parameters disappears, and we recover uniform bulk ground states. The effect of the boundary conditions on the entanglement spectrum is also investigated.

Furthermore, we elaborate on the quench dynamics and discuss the results in terms of our findings on the equilibrium phases.