Abstract
Recently, the stability of certain topological phases of matter under weak perturbations was proven. Here, we present a short, alternate proof of the same result. We consider models of topological quantum order for which the unperturbed Hamiltonian H 0 can be written as a sum of local pairwise commuting projectors on a D-dimensional lattice. We consider a perturbed Hamiltonian H = H 0 + V involving a generic perturbation V that can be written as a sum of short-range bounded-norm interactions. We prove that if the strength of V is below a constant threshold value then H has well-defined spectral bands originating from the low-lying eigenvalues of H 0. These bands are separated from the rest of the spectrum and from each other by a constant gap. The width of the band originating from the smallest eigenvalue of H 0 decays faster than any power of the lattice size.
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Communicated by I.M. Sigal
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Bravyi, S., Hastings, M.B. A Short Proof of Stability of Topological Order under Local Perturbations. Commun. Math. Phys. 307, 609–627 (2011). https://doi.org/10.1007/s00220-011-1346-2
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DOI: https://doi.org/10.1007/s00220-011-1346-2