Janus Black Holes

TL;DR

This paper studies Janus black holes in AdS3, exploring their solutions, thermodynamics, and entropy, revealing how the black hole entropy relates to entanglement entropy in interface conformal field theories.

Contribution

It provides approximate, numerical, and exact solutions for Janus black holes, and analyzes their thermodynamics and entropy, linking gravitational and quantum entanglement aspects.

Findings

Entropy equals the sum of undeformed black hole entropy and defect entanglement entropy.

Constructed approximate solutions using perturbation theory.

Derived exact solutions valid for all parameters.

Abstract

In this paper Janus black holes in AdS3 are considered. These are static solutions of an Einstein-scalar system with broken translation symmetry along the horizon. These solutions are dual to interface conformal field theories at finite temperature. An approximate solution is first constructed using perturbation theory around a planar BTZ black hole. Numerical and exact solutions valid for all sets of parameters are then found and compared. Using the exact solution the thermodynamics of the system is analyzed. The entropy associated with the Janus black hole is calculated and it is found that the entropy of the black Janus is the sum of the undeformed black hole entropy and the entanglement entropy associated with the defect.