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arXiv · 1403.3982

Destroying a topological quantum bit by condensing Ising vortices

Zhihao Hao·Stephen Inglis·Roger Melko
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Abstract

The imminent realization of topologically-protected qubits in fabricated systems will provide not only an elementary implementation of fault-tolerant quantum computing architecture, but also an experimental vehicle for the general study of topological order. The simplest topological qubit harbors what is known as a Z$_2$ liquid phase, which encodes information via a degeneracy depending on the system's topology. Elementary excitations of the phase are fractionally charged objects called {\it spinons}, or Ising flux vortices called {\it visons}. At zero temperature a Z$_2$ liquid is stable under deformations of the Hamiltonian until spinon or vison condensation induces a quantum phase transition destroying the topological order. In this paper, we use quantum Monte Carlo to study a vison-induced transition from a Z$_2$ liquid to a valence-bond solid in a quantum dimer model on the kagome lattice. Our results indicate that this critical point is controlled by a new universality class beyond the standard Landau paradigm.

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Zhihao Hao, Stephen Inglis, Roger Melko. 2014-12-17. Destroying a topological quantum bit by condensing Ising vortices. https://doi.org/10.1038/ncomms6781

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