Correlations of mixed systems in confining backgrounds

TL;DR

This paper investigates how entanglement measures like entanglement of purification and critical distance between mixed systems can reveal phase structures in confining backgrounds relevant to QCD, using numerical calculations across various geometries.

Contribution

It introduces the use of entanglement of purification and critical distance as probes for phase transitions in confining geometries, providing new tools for understanding QCD-like backgrounds.

Findings

Critical distance vanishes at phase transition points.

Entanglement of purification relates to confinement scales.

Crofton forms exhibit universal behavior around IR walls.

Abstract

We show that the entanglement of purification and the critical distance between the two mixed systems is a powerful measure in probing the phase structures of QCD and confining backgrounds, as it can distinguish the scale of chiral symmetry breaking versus the scale of confinement/deconfinement phase transitions. For two symmetric strips with equal and finite width and infinite length, and in the background of several confining geometries, we numerically calculate the critical distance between them where the mutual information vanishes and show that this quantity can probe the very rich phase structures of these backgrounds. The geometries that we study here are AdS-soliton, Witten Sakai Sugimoto and deformed Sakai-Sugimoto, Witten-QCD, Klebanov-Strassler, Klebanov-Tseytlin, Klebanov-Witten, Maldacena-Nunez, Nunez-Legramandi metric, and Domain-Wall QCD model. For each background we also present the relation for the entanglement of purification. Finally, we show that the Crofton forms of these geometries also behave in a universal form where a "well" is being observed around the IR wall, and therefore for all confining backgrounds, the Crofton form would also be capable of distinguishing the confining versus conformal backgrounds as it is also a tool in the reconstruction of various bulk geometries.