Near Extremal Black Hole Entropy as Entanglement Entropy via AdS2/CFT1

TL;DR

This paper demonstrates that the entropy of near extremal black holes can be understood as entanglement entropy in dual conformal quantum mechanics, providing explicit calculations and clarifying the thermal-entanglement entropy relationship.

Contribution

It establishes a connection between black hole entropy and entanglement entropy via AdS2/CFT1, supported by explicit examples and analytical computations.

Findings

Black hole entropy can be interpreted as entanglement entropy in dual CFT.

Explicit calculation for near extremal BTZ black holes supports the interpretation.

Analytical results for free Dirac fermion CFT clarify thermal and entanglement entropy relation.

Abstract

We point out that the entropy of (near) extremal black holes can be interpreted as the entanglement entropy of dual conformal quantum mechanics via AdS2/CFT1. As an explicit example, we study near extremal BTZ black holes and derive this claim from AdS3/CFT2. We also analytically compute the entanglement entropy in the two dimensional CFT of a free Dirac fermion compactified on a circle at finite temperature. From this result, we clarify the relation between the thermal entropy and entanglement entropy, which is essential for the entanglement interpretation of black hole entropy.