Quantum Black Hole Evaporation

TL;DR

This paper presents a quantum model of two-dimensional black hole evaporation that reproduces thermal radiation, incorporates acausal effects near the singularity, and demonstrates information preservation in the final state.

Contribution

It introduces a full quantum description with boundary conditions, showing how information is preserved and how corrections to Hawking radiation arise from strong coupling effects.

Findings

Outgoing radiation is approximately thermal, matching semi-classical predictions.

Acausal effects near the singularity modify the Hawking spectrum.

The final state retains all initial information, indicating unitarity.

Abstract

We investigate a recently proposed model for a full quantum description of two-dimensional black hole evaporation, in which a reflecting boundary condition is imposed in the strong coupling region. It is shown that in this model each initial state is mapped to a well-defined asymptotic out-state, provided one performs a certain projection in the gravitational zero mode sector. We find that for an incoming localized energy pulse, the corresponding out-going state contains approximately thermal radiation, in accordance with semi-classical predictions. In addition, our model allows for certain acausal strong coupling effects near the singularity, that give rise to corrections to the Hawking spectrum and restore the coherence of the out-state. To an asymptotic observer these corrections appear to originate from behind the receding apparent horizon and start to influence the out-going state long before the black hole has emitted most of its mass. Finally, by putting the system in a finite box, we are able to derive some algebraic properties of the scattering matrix and prove that the final state contains all initial information.