Uniform bound of the entanglement for the ground state of the one-dimensional quantum Ising model with non-homogeneous transverse field

Abstract

We consider the ground state of the one-dimensional quantum Ising model with transverse field $h_x$ in one dimension depending on the site $x \in \mathbb Z$ in a finite volume $\Lambda_{m}:=\{-m,-m+1,\ldots,m+L\}\ $. We make suitable assumptions on the regions where the field is small and prove that if the field is sufficiently large on the complementary set, then the entanglement of the interval $\Lambda_{0}:=\left\{ 0,..,L\right\} $ relative to its complement $\Lambda_{m}\backslash\Lambda_{0}$ is bounded uniformly in $m$ and $L$. The result applies in particular to periodic transverse fields. The bound is established by means of a suitable cluster expansion.