2015/01/31 by Jacob C. Bridgeman, Aroon O’Brien, Aroon O'Brien +2 · 1 citation
Physics and Astronomy · #Ansatz #Boson #Conformal field theory #Conformal map #Critical phenomena #Global symmetry #Mathematical physics #Orbifold #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum #Quantum and electron transport phenomena #Quantum entanglement #Quantum many-body systems #Quantum mechanics #Renormalization group #Spin (aerodynamics) #Spontaneous symmetry breaking #Symmetry breaking #Theoretical physics #cond-mat.str-el #quant-ph
paper · pdf · doi:10.1103/physrevb.91.165129
published as Phys. Rev. B 91, 165129 (2015) · 13 pages, 11 figures, comments welcome; v2 published version
openalex publication_date 2015/04/24 · arxiv created 2015/04/26 · arxiv updated 2015/04/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We use the multiscale entanglement renormalization ansatz (MERA) to numerically investigate three critical quantum spin chains with Z2\ifmmode×\else\texttimes\fiZ2 on-site symmetry: a staggered XXZ model, a transverse field cluster model, and the quantum Ashkin-Teller model. All three models possess a continuous one-parameter family of critical points. Along this critical line, the thermodynamic limit of these models is expected to be described by classes of c=1 conformal field theories (CFTs) of two possible types: the S1 free boson and its Z2 orbifold. Our numerics using MERA with explicitly enforced Z2\ifmmode×\else\texttimes\fiZ2 symmetry allow us to extract conformal data for each model, with strong evidence supporting the identification of the staggered XXZ model and critical transverse field cluster model with the S1 boson CFT, and the Ashkin-Teller model with the Z2-orbifold boson CFT. Our first two models describe the phase transitions between symmetry-protected topologically ordered phases and trivial phases, which lie outside the usual Landau-Ginsburg-Wilson paradigm of symmetry breaking. Our results show that a range of critical theories can arise at the boundary of a single symmetry protected phase.