684 research outputs found
Macroscopic Quantum Tunneling Effect of Z2 Topological Order
In this paper, macroscopic quantum tunneling (MQT) effect of Z2 topological
order in the Wen-Plaquette model is studied. This kind of MQT is characterized
by quantum tunneling processes of different virtual quasi-particles moving
around a torus. By a high-order degenerate perturbation approach, the effective
pseudo-spin models of the degenerate ground states are obtained. From these
models, we get the energy splitting of the ground states, of which the results
are consistent with those from exact diagonalization methodComment: 25 pages, 14 figures, 4 table
Topological Mid-gap States of Topological Insulators with Flux-Superlattice
In this paper based on the Haldane model, we study the topological insulator
with superlattice of pi-fluxes. We find that there exist the mid-gap states
induced by the flux-superlattice. In particular, the mid-gap states have
nontrivial topological properties, including the nonzero Chern number and the
gapless edge states. We derive an effective tight-binding model to describe the
topological midgap states and then study the mid-gap states by the effective
tight-binding model. The results can be straightforwardly generalized to other
two dimensional topological insulators with flux-superlattice.Comment: 6 pages, 9 figure
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