States of 2D Yang-Mills and Large-Volume Entanglement

TL;DR

This paper investigates entanglement properties in 2D Yang-Mills theory, revealing how entanglement varies with area, topological defects, and Wilson lines, and uncovering finite entanglement at infinite volume in specific configurations.

Contribution

It introduces a detailed analysis of entanglement in 2D Yang-Mills, highlighting non-monotonic behavior and finite entanglement in certain large-volume limits, with implications for confinement.

Findings

Entanglement decreases with area and defects, becoming separable at infinite area.

Wilson lines cause non-monotonic entanglement behavior.

Certain configurations maintain finite entanglement even at infinite volume.

Abstract

We study entanglement in two-dimensional Yang-Mills theory, viewed as a quasi-topological model of emergent space. The most familiar class of states in this theory are states defined by Euclidean path integrals over Riemann surfaces. Bipartite states of this class have thermofield double structure, with entanglement consistently reducing with total area and the number of topological defects, turning separable in the infinite-area limit. In contrast, Wilson lines and loops generate rich non-monotonic behavior of the entanglement entropy. Most notably, we find that for a certain discrete set of configurations, entanglement remains finite at infinite area. The reduced density matrices, in such configurations, take the form of finite-dimensional projectors onto non-trivial vacuum sectors. We also discuss the implications of the large-volume effects for confinement and find that special asymptotic configurations are related to transitions in the confining force.