Large-$d$ phase transitions in holographic mutual information

TL;DR

This paper analyzes phase transitions in holographic mutual information within the AdS/CFT framework, deriving analytical results in the large-$d$ limit and providing numerical insights for various spacetime dimensions.

Contribution

It provides the first analytical computation of the mutual information phase transition in the large-$d$ limit and compares it with numerical results across multiple dimensions.

Findings

Distant regions cannot develop large correlations without occupying the entire boundary volume in large-$d$.

Analytical results in the large-$d$ limit show decoupling of correlations.

Numerical results for dimensions 4 to 21 support and extend the analytical findings.

Abstract

In the AdS/CFT correspondence, the entanglement entropy of subregions in the boundary CFT is conjectured to be dual to the area of a bulk extremal surface at leading order in $G_N$ in the holographic limit. Under this dictionary, distantly separated regions in the CFT vacuum state have zero mutual information at leading order, and only attain nonzero mutual information at this order when they lie close enough to develop significant classical and quantum correlations. Previously, the separation at which this phase transition occurs for equal-size ball-shaped regions centered at antipodal points on the boundary was known analytically only in $3$ spacetime dimensions. Inspired by recent explorations of general relativity at large-$d$, we compute the separation at which the phase transition occurs analytically in the limit of infinitely many spacetime dimensions, and find that distant regions cannot develop large correlations without collectively occupying the entire volume of the boundary theory. We interpret this result as illustrating the spatial decoupling of holographic correlations in the large-$d$ limit, and provide intuition for this phenomenon using results from quantum information literature. We also compute the phase transition separation numerically for a range of bulk spacetime dimensions from $4$ to $21$, where analytic results are intractable but numerical results provide insight into the dimension-dependence of holographic correlations. For bulk dimensions above $5$, our exact numerical results are well approximated analytically by working to next-to-leading order in the large-$d$ expansion.