We propose a simple mean-field ansatz to study phase transitions from a topological phase to a trivial phase. We probe the efficiency of this approach by considering the string-net model in the presence of a string tension for any anyon theory. Such a perturbation is known to be responsible for a deconfinement-confinement phase transition which is well described by the present variational setup. We argue that mean-field results become exact in the limit of large total quantum dimension.

arXiv:1506.03259Physical Review BSep 29, 201521 citations

arXiv:1401.1033 · Physical Review B

Ising anyons with a string tension

Marc Daniel Schulz, Sébastien Dusuel, Grégoire Misguich, Kai Phillip Schmidt, Julien Vidal

Published May 7, 2014• 33 citations

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Abstract

DOI: 10.1103/physrevb.89.201103

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({\mathbb{Z}}_{2})

and non-Abelian $(\text{Ising}\ifmmode\times\else\texttimes\fi{}\overline{\text{Ising}})$ topologically ordered phases, as well as phases with broken translational symmetry. Interestingly, one of these phases simultaneously exhibits (Abelian) topological order and long-ranged order due to translational symmetry breaking, with nontrivial interactions between excitations in the topological order and defects in the long-ranged order. We introduce a variety of effective models, valid along certain lines in the phase diagram, which can be used to characterize both topological and symmetry-breaking order in these phases and in many cases allow us to characterize the phase transitions that separate them. We use exact diagonalization and high-order series expansion to study areas of the phase diagram where these models break down and to approximate the location of the phase boundaries.

{\mathbb{Z}}_{2}

string nets and capture the second-order phase transition which is well known from the exact mapping onto the transverse-field Ising model. More interestingly, for Fibonacci string nets, we obtain first-order transitions in contrast with previous studies but in qualitative agreement with mean-field results.