Fabian Grusdt, Michael Hoening, Michael Fleischhauer
We analyze the ground state of interacting ultra-cold bosonic atoms in a one-dimensional (1D) super-lattice potential with alternating tunneling rates t_1 and t_2. A topological order parameter is introduced which is quantized in units of pi for the Mott insulating (MI) phases. A step in the effective confining potential created e.g. by a second heavy atom species can lead to an interface between two MI regions with filling n=1 and n=1/2. Depending on the ratio t_1/t_2 the n=1/2 MI phase is topologically non-trivial which results in localized, protected many-body edge states. Density-matrix renormalization group (DMRG) simulations show that the edge states manifest themselves either in localized density minima or localized density maxima at the interface, which can easily be detected. 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 DMRG simulations.
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http://arxiv.org/abs/1301.7242
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