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An extended Hubbard model with ring exchange: a route to a non-Abelian topological phase

Michael Freedman·Chetan Nayak·Kirill Shtengel
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Abstract

We propose an extended Hubbard model on a 2D Kagome lattice with an additional ring-exchange term. The particles can be either bosons or spinless fermions . At a special filling fraction of 1/6 the model is analyzed in the lowest non-vanishing order of perturbation theory. Such ``undoped'' model is closely related to the Quantum Dimer Model. We show how to arrive at an exactly soluble point whose ground state manifold is the extensively degenerate ``d-isotopy space'', a necessary precondition for for a certain type of non-Abelian topological order. Near the ``special'' values, $d = 2 \cos π/(k+2)$, this space is expected to collapse to a stable topological phase with anyonic excitations closely related to SU(2) Chern-Simons theory at level k.

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Michael Freedman, Chetan Nayak, Kirill Shtengel. 2004-11-09. An extended Hubbard model with ring exchange: a route to a non-Abelian topological phase. https://doi.org/10.1103/physrevlett.94.066401

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