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Cosmology from random entanglement

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arxiv 2307.14416 v4 pith:EL2Z2O7Z submitted 2023-07-26 hep-th gr-qc

classification hep-thgr-qc
keywords cosmologyentanglementcftsbulkcosmology-to-boundarynon-isometricstatesacting
verification ladder T0 review T1 audit T2 compute T3 formal
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We construct entangled microstates of a pair of holographic CFTs whose dual semiclassical description includes big bang-big crunch AdS cosmologies in spaces without boundaries. The cosmology is supported by inhomogeneous heavy matter and it partially purifies the bulk entanglement of two disconnected auxiliary AdS spacetimes. We show that the island formula for the fine grained entropy of one of the CFTs follows from a standard gravitational replica trick calculation. In generic settings, the cosmology is contained in the entanglement wedge of one of the two CFTs. We then investigate properties of the cosmology-to-boundary encoding map, and in particular, its non-isometric character. Restricting our attention to a specific class of states on the cosmology, we provide an explicit, and state-dependent, boundary representation of operators acting on the cosmology. Finally, under genericity assumptions, we argue for a non-isometric to approximately-isometric transition of the cosmology-to-boundary map for ``simple'' states on the cosmology as a function of the bulk entanglement, with tensor network toy models of our setup as a guide.

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Cited by 7 Pith papers

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