Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 49: Quantum gases: Lattices I

Q 49.5: Talk

Thursday, March 20, 2014, 17:30–17:45, UDL HS2002

Bulk Phases and Topological Edge State in the extended 1D Superlattice Bose-Hubbard Model — •Hsiang-Hua Jen, Michael Höning, Fabian Grusdt, and Michael Fleischhauer — Department of Physics, Technische Universität Kaiserslautern, Kaiserslautern, Germany

We investigate ultracold bosonic atoms in a one-dimensional (1D) superlattice with alternating hopping rates, nearest neighbor (NN), and next NN interactions. Motivated by the nontrivial topological edge states in the n=1/2 Mott-insulating (MI) phase [1], we study the quarter filling phase with a fixed ratio of hopping rates (t1/t2) with open boundaries. Depending on the position of the boundary we find localized edge state as well as delocalized single quasihole or quasiparticle states in the bulk. The local excitation at the edge can be melted into the bulk as the hopping increases, and a delocalized quasiparticle emerges.

We use DMRG to analyze the grand canonical phase diagram with sharp boundaries. Within the lobe of the n=1/4 MI phase, a transition from single quasihole to quasiparticle states in the bulk occurs. The existence of this transition is a result of the fractional charge excitations and therefore of nontrivial topology.

[1] F. Grusdt, M. Höning, and M. Fleischhauer, Phys. Rev. Lett. 110, 260405 (2013).