Destroying a topological quantum bit by condensing Ising vortices

作者：Hao Zhihao^*; Inglis Stephen; Melko Roger

来源：Nature Communications, 2014, 5(1): 5781.

DOI：10.1038/ncomms6781

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 harbours what is known as a Z(2) liquid phase, which encodes information via a degeneracy depending on the system%26apos;s topology. Elementary excitations of the phase are fractionally charged objects called spinons, or Ising flux vortices called 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. Here 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 beyond the description of the standard Landau paradigm.

• 出版日期2014-12