arXiv subjects

Michael Höning

Publications and source records attributed to Michael Höning.

2 recordsLinked to original sources

arXiv2014

Realization of Fractional Chern Insulators in the Thin-Torus-Limit with Ultracold Bosons

Topological states of interacting many-body systems are at the focus of current research due to the exotic properties of their elementary excitations. In this paper we suggest a realistic experimental setup for the realization of a simple version of such a phase. We show how delta-interacting bosons hopping on the links of a one-dimensional (1D) ladder can be used to simulate the thin-torus-limit of the two-dimensional (2D) Hofstadter-Hubbard model at one-quarter magnetic flux per plaquette. Bosons can be confined to ladders by optical superlattices, and synthetic magnetic fields can be realized by far off-resonant Raman beams. We show that twisted boundary conditions can be implemented, enabling the realization of a fractionally quantized Thouless pump. Using numerical density-matrix-renormalization-group (DMRG) calculations we show that the groundstate of our model is an incompressible symmetry-protected topological charge density wave (CDW) phase at average filling $ρ= 1/8$ per lattice site, related to the 1/2 Laughlin-type state of the corresponding 2D model.

cond-mat.quant-gas↗

arXiv2013

Topological edge states in the one-dimensional super-lattice Bose-Hubbard model

We analyze interacting ultra-cold bosonic atoms in a one-dimensional (1D) super-lattice potential with alternating tunneling rates t_1 and t_2 and inversion symmetry, which is the bosonic analogue of the Su-Schrieffer-Heeger (SSH) model. A Z2 topological order parameter is introduced which is quantized for the Mott insulating (MI) phases. Depending on the ratio t_1/t_2 the n=1/2 MI phase is topologically non-trivial, which results in many-body edge states at open boundaries. In contrast to the SSH model the bosonic counterpart lacks chiral symmetry and the edge states are no longer mid-gap. This leads to a generalization of the bulk-edge correspondence, which we discuss in detail. The edge states can be observed in cold atom experiments by creating a step in the effective confining potential, e.g. by a second heavy atom species, which leads to an interface between two MI regions with filling n=1 and n=1/2. Shape and energy of the edge states as well as conditions for their occupation are determined analytically in the strong coupling limit and in general by density-matrix renormalization group (DMRG) simulations.

cond-mat.quant-gas↗