Islands and mixed states in closed universes

Fallows, Seamus; Ross, Simon F.

Abstract

We investigate the appearance of islands when a closed universe with gravity is entangled with a non-gravitating quantum system. We use braneworlds in three-dimensional multiboundary wormhole geometries as a model to explore what happens when the non-gravitating system has several components. The braneworld can be either completely contained in the entanglement wedge of one of the non-gravitating systems or split between them. In the former case, entanglement with the other system leads to a mixed state in the closed universe, unlike in simpler setups with a single quantum system, where the closed universe was necessarily in a pure state. We show that the entropy of this mixed state is bounded by half of the coarse-grained entropy of the effective theory on the braneworld.

Citation

Fallows, S., & Ross, S. F. (2021). Islands and mixed states in closed universes. Journal of High Energy Physics, 2021(7), Article 22. https://doi.org/10.1007/jhep07%282021%29022

• Journal Article Type: Article
• Acceptance Date: Jun 17, 2021
• Online Publication Date: Jul 6, 2021
• Publication Date: 2021
• Deposit Date: Jul 9, 2021
• Publicly Available Date: Oct 21, 2021
• Journal: Journal of High Energy Physics
• Print ISSN: 1126-6708
• Electronic ISSN: 1029-8479
• Publisher: Scuola Internazionale Superiore di Studi Avanzati (SISSA)
• Peer Reviewed: Peer Reviewed
• Volume: 2021
• Issue: 7
• Article Number: 22
• DOI: https://doi.org/10.1007/jhep07%282021%29022
• Public URL: https://durham-repository.worktribe.com/output/1272597
• Related Public URLs: https://arxiv.org/abs/2103.14364