2021/03/31 by Seamus Fallows, Simon F. Ross
Physics and Astronomy · #Black Holes and Theoretical Physics #Bounded function #Cosmology and Gravitation Theories #Entropy (arrow of time) #Noncommutative and Quantum Gravity Theories #Quantum #Quantum entanglement #Quantum gravity #Squashed entanglement #Universe #Wedge (geometry) #Wormhole #hep-th
paper · pdf · doi:10.1007/jhep07(2021)022
21 pages, v2: reference added, v3: clarifying comments added in response to referee report
openalex created_date 2021/04/13 · arxiv created 2021/06/01 · openalex publication_date 2021/07/01 · arxiv updated 2021/07/21 · openalex updated_date 2026/08/05
A bstract 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.