Operational islands and black hole dissipation in JT gravity

TL;DR

This paper investigates entanglement islands and black hole dissipation in JT gravity, demonstrating a unitary Page curve with an island outside the horizon and analyzing black hole evolution including charge and supersymmetry effects.

Contribution

It introduces a new setup for entanglement islands in JT gravity using a fiducial detector and boundary observer's entropy, providing explicit calculations of the Page curve and black hole dissipation.

Findings

Explicit unitary Page curve with an island outside the horizon

Charged black holes grow via superradiation before dissipating

Similar dissipation behavior observed in supersymmetric black holes

Abstract

In this work, we revisit the problem of finding entanglement islands in 2d Jackiw-Teitelboim (JT) gravity. We implement the following adjustments to the traditional setup: (1) we do not explicitly couple to a non-gravitating system, instead we implement only pure absorption into a fiducial detector, (2) we utilise the operationally defined renormalised matter entanglement entropy, as defined by the boundary observer's wordline. We show that this leads to a unitary Page curve that we explicitly compute, with an island outside of the event horizon. Next, we extend the analysis to a charged and/or supersymmetric black hole. We find that in a certain regime the charged black hole grows first as it emits superradiation before eventually dissipating. We obtain similar results when embedding the system in a supersymmetric setting.