Characterization of topological phases in the compass ladder model
Abstract
The phase diagram of the quantum compass ladder model is investigated through numerical density matrix renormalization group based on infinite matrix product state algorithm and analytic effective perturbation theory. For this model we obtain two symmetryprotected topological phases, protected by a {{Z}_{2}}× {{Z}_{2}} symmetry, and a topologicallytrivial Z _{2}symmetrybreaking phase. The symmetryprotected topological phases—labeled by symmetry fractionalization—belong to different topological classes, where the complexconjugate symmetry uniquely distinguishes them. An important result of this classification is that, as revealed by the nature of the Z _{2}symmetrybreaking phase, the associated quantum phase transitions are accompanied by an explicit symmetry breaking, and thus a localorder parameter conclusively identifies the phase diagram of the underlying model. This is in stark contrast to previous studies which require a nonlocal string order parameter to distinguish the corresponding quantum phase transitions. We numerically examine our results and show that the localorder parameter is related to the magnetization exponent 0.12+/ 0.01 .
 Publication:

Journal of Physics Condensed Matter
 Pub Date:
 May 2016
 DOI:
 10.1088/09538984/28/17/176001
 arXiv:
 arXiv:1509.00207
 Bibcode:
 2016JPCM...28q6001H
 Keywords:

 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 10 pages, 6 figures