English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The island rule for the entanglement entropy is applied to an eternalReissner-Nordstr\"om black hole. The key ingredient is that the black hole isassumed to be in thermal equilibrium with a heat bath of an arbitrarytemperature and so the generalized entropy is treated as being off-shell.Taking the on-shell condition to the off-shell generalized entropy, we find thegeneralized entropy and then obtain the entanglement entropy following theisland rule. For the non-extremal black hole, the entanglement entropy growslinearly in time and can be saturated after the Page time as expected. Theentanglement entropy also has a well-defined Schwarzschild limit. In theextremal black hole, the island prescription provides a logarithmically growingentanglement entropy in time and a constant entanglement entropy after the Pagetime. In the extremal black hole, the boundary of the island hits the curvaturesingularity where the semi-classical approximations appear invalid. To avoidencountering the curvature singularity, we apply this procedure to the Haywardblack hole regular at the origin. Consequently, the presence of the island inextremal black holes can provide a finite entanglement entropy, which mightimply non-trivial vacuum configurations of extremal black holes.

Entanglement entropy of asymptotically flat non-extremal and extremal black holes with an island