Semi-classical thermodynamics of quantum extremal surfaces in Jackiw-Teitelboim gravity

Understand

Quantum extremal surfaces (QES), codimension-2 spacelike regions which extremize the generalized entropy of a gravity-matter system, play a key role in the study of the black hole information problem.

• The thermodynamics of QESs, however, has been largely unexplored, as a proper interpretation requires a detailed understanding of backreaction due to quantum fields.
• We investigate this problem in semi-classical Jackiw-Teitelboim (JT) gravity, where the spacetime is the eternal two-dimensional Anti-de Sitter ($\text{AdS}_{2}$) black hole, Hawking radiation is described by a conformal field theory with central charge $c$, and backreaction effects may be analyzed exactly.
• We show the Wald entropy of the semi-classical JT theory entirely encapsulates the generalized entropy - including time-dependent von Neumann entropy contributions - whose extremization leads to a QES lying just outside of the black hole horizon.