Finitely Correlated States Driven by Topological Dynamics

Abstract

Let $(Ω, ¶)$ be a standard probability space and let $\vartheta:Ω\to Ω$ be a measure preserving ergodic homeomorphism. Let $\mathcal{A}$ be a $C^*$-algebra with a unit and let $\mathcal{A}_{\mathbb{Z}}$ be the quasi-local algebra associated to the spin chain with one-site algebra $\mathcal{A}$. Equip $\mathcal{A}_{\mathbb{Z}}$ with the group action of translation by $k$-units, $τ_k\in Aut(\mathcal{A}_{\mathbb{Z}})$ for $k\in \mathbb{Z}$. We study the problem of finding a disordered matrix product state decomposition for disordered states $ψ(ω)$ on $\mathcal{A}_{\mathbb{Z}}$ with the covariance symmetry condition $ψ(ω) \circ τ_k = ψ(\vartheta^k ω)$. This can be seen as an ergodic generalization of the results of Fannes, Nachtergaele, and Werner [31]. To reify our structure theory, we present a disordered state $ν_ω$ obtained by sampling the AKLT model [2] in parameter space. We go on to show that $ν_ω$ has a nearest-neighbor parent Hamiltonian, its bulk spectral gap closes, but it has almost surely exponentially decaying correlations, and finally, that $ν_ω$ is time-reversal invariant with a Tasaki index of $-1$ almost surely.