The Entanglement Renyi Entropies of Disjoint Intervals in AdS/CFT

TL;DR

This paper investigates entanglement Renyi entropies for disjoint intervals in 1+1 dimensional CFTs with gravity duals, identifying specific bulk solutions and relating their classical actions to entanglement measures.

Contribution

It introduces two families of handlebody solutions in AdS3 gravity that correspond to entanglement Renyi entropies of disjoint intervals, maintaining replica symmetry.

Findings

Derived a simple numerical prescription for the classical action of bulk solutions.

Connected the classical action to entanglement Renyi entropies at leading order.

Reproduced the Ryu-Takayanagi formula for entanglement entropy in the limit n -> 1.

Abstract

We study entanglement Renyi entropies (EREs) of 1+1 dimensional CFTs with classical gravity duals. Using the replica trick the EREs can be related to a partition function of n copies of the CFT glued together in a particular way along the intervals. In the case of two intervals this procedure defines a genus n-1 surface and our goal is to find smooth three dimensional gravitational solutions with this surface living at the boundary. We find two families of handlebody solutions labelled by the replica index n. These particular bulk solutions are distinguished by the fact that they do not spontaneously break the replica symmetries of the boundary surface. We show that the regularized classical action of these solutions is given in terms of a simple numerical prescription. If we assume that they give the dominant contribution to the gravity partition function we can relate this classical action to the EREs at leading order in G_N. We argue that the prescription can be formulated for non-integer n. Upon taking the limit n -> 1 the classical action reproduces the predictions of the Ryu-Takayanagi formula for the entanglement entropy.