Islands and dynamics at the interface

TL;DR

This paper explores a holographic model with two coupled CFT$_2$s separated by an interface, using a lower-dimensional JT gravity framework to compute entanglement entropy and Page curves, confirming results with bulk geometry calculations.

Contribution

It introduces a novel effective JT gravity model for interface CFTs and demonstrates precise agreement with bulk holographic computations for entanglement entropy.

Findings

Agreement between island prescription and bulk calculations in large brane tension limit

Explicit derivation of Page curves for Hawking radiation in the model

Effective lower-dimensional description captures interface dynamics accurately

Abstract

We investigate a family of models described by two holographic CFT$_2$s coupled along a shared interface. The bulk dual geometry consists of two AdS$_3$ spacetimes truncated by a shared Karch-Randall end-of-the-world (EOW) brane. A lower dimensional effective model comprising of JT gravity coupled to two flat CFT$_2$ baths is subsequently realized by considering small fluctuations on the EOW brane and implementing a partial Randall-Sundrum reduction where the transverse fluctuations of the EOW brane are identified as the dilaton field. We compute the generalized entanglement entropy for bipartite states through the island prescription in the effective lower dimensional picture and obtain precise agreement in the limit of large brane tension with the corresponding doubly holographic computations in the bulk geometry. Furthermore, we obtain the corresponding Page curves for the Hawking radiation in this JT braneworld.