Islands in Flat-Space Cosmology

TL;DR

This paper resolves the information paradox in flat-space cosmologies by applying the island proposal, demonstrating that the entropy of Hawking radiation follows a Page curve and enabling information extraction via quantum teleportation.

Contribution

It introduces the island proposal to flat-space cosmologies, showing how to resolve the information paradox and proposing a quantum teleportation protocol for information retrieval.

Findings

Entropy of radiation follows a Page curve with islands.

Adding islands resolves the information paradox.

Quantum teleportation can extract information from islands.

Abstract

Flat-space cosmologies (FSC) are solutions to three dimensional theories of gravity without cosmological constant that have cosmological horizons. A detector located near the time-like singularity of the spacetime can absorb Hawking modes that are created near the horizon. Continuation of this process will eventually cause the entropy of the radiation to be larger than the entropy of the FSC, which leads to the information paradox. In this paper, we resolve this paradox for the FSC using the island proposal. To do this, we couple an auxiliary flat bath system to this spacetime in timelike singularity so that Hawking modes are allowed to enter the bath and the entropy of radiation can be measured in its asymptotic region where gravity is also weak. We show that adding island regions that receive the partners of Hawking modes cause the entropy of radiation to follow a Page curve which leads to resolving the information paradox. Moreover, we design a quantum teleportation protocol by which one can extract the information residing in islands.