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Symmetry protection of topological phases in one-dimensional quantum spin systems

2012; American Physical Society; Volume: 85; Issue: 7 Linguagem: Inglês

10.1103/physrevb.85.075125

1550-235X

Frank Pollmann, Erez Berg, Ari M. Turner, Masaki Oshikawa,

Quantum and electron transport phenomena

We discuss the characterization and stability of the Haldane phase in integer spin chains on the basis of simple, physical arguments. We find that an odd-$S$ Haldane phase is a topologically nontrivial phase which is protected by any one of the following three global symmetries: (i) the dihedral group of $\ensuremath{\pi}$ rotations about the $x$, $y$, and $z$ axes, (ii) time-reversal symmetry ${S}^{x,y,z}\ensuremath{\rightarrow}\ensuremath{-}{S}^{x,y,z}$, and (iii) link inversion symmetry (reflection about a bond center), consistent with previous results [Phys. Rev. B 81, 064439 (2010)]. On the other hand, an even-$S$ Haldane phase is not topologically protected (i.e., it is indistinct from a trivial, site-factorizable phase). We show some numerical evidence that supports these claims, using concrete examples.