arXiv:1512.05229 · Physical review. B./Physical review. B
Chiral Haldane phases of SU(N) quantum spin chains
Abhishek Roy, Thomas Quella
Abstract
Gapped quantum spin chains with symmetry $\text{PSU}(N)=\text{SU}(N)/{\mathbb{Z}}_{N}$ are known to possess $N$ distinct symmetry protected topological phases. Besides the trivial phase, there are $N\ensuremath{-}1$ Haldane phases which are distinguished by the occurrence of massless boundary spins. We give an expression for a universal AKLT Hamiltonian for an arbitrary symmetry group, including the case where inversion symmetry is broken. Using a diagrammatic method, we construct Hamiltonians for two of the topological classes in $\text{SU}(N)$ that arise when the physical spin is in the adjoint representation. Since our results are valid for all $N$, we also discuss the large-$N$ limit.