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DATE | 2018-06-11 |

TIME | 12:10 |

PLACE | R49223, Second Physics Building , NCKU |

FIELD | Quantum Information Science |

SPEAKER | Prof. Ching-Yu Huang - 國家理論科學研究中心 |

TITLE | Classifying quantum states andUniversal measurement-based quantum computationby using tensor-network state |

ABSTRACT | Symmetry-protected topological (SPT) phases exhibit nontrivial order if symmetry is respected but are adiabatically connected to the trivial product phase if symmetry is not respected. However, unlike the symmetry breaking phase, there is no local order parameter for SPT phases. Here we employ a tensor-network method to compute the topological invariants characterized by the simulated modular S and T matrices to study transitions in a few families of two-dimensional (2D) wave functions which are ZN (N = 2 and 3) symmetric. We find that in addition to the topologically ordered phases, the modular matrices can be used to identify nontrivial SPT phases and detect transitions between different SPT phases as well as between symmetric and symmetry-breaking phases. Therefore modular matrices can be used to characterize various types of gapped phases in a unifying way.On the other hand,the quantum computational power appears to lose its universality at the boundary between the SPT and the symmetry-breaking phases. |