442 research outputs found
Holographic tensor network models and quantum error correction: A topical review
Recent progress in studies of holographic dualities, originally motivated by
insights from string theory, has led to a confluence with concepts and
techniques from quantum information theory. A particularly successful approach
has involved capturing holographic properties by means of tensor networks which
not only give rise to physically meaningful correlations of holographic
boundary states, but also reproduce and refine features of quantum error
correction in holography. This topical review provides an overview over recent
successful realizations of such models. It does so by building on an
introduction of the theoretical foundations of AdS/CFT and necessary quantum
information concepts, many of which have themselves developed into independent,
rapidly evolving research fields.Comment: 43 pages, 12 figure
TT and EE, with implications for (A)dS subregion encodings
We initiate a study of subregion dualities, entropy, and redundant encoding of bulk points in holographic theories deformed by TT and its generalizations. This includes both cut off versions of Anti de Sitter spacetime, as well as the generalization to bulk de Sitter spacetime, for which we introduce two additional examples capturing different patches of the bulk and incorporating the second branch of the square root dressed energy formula. We provide new calculations of entanglement entropy (EE) for more general divisions of the system than the symmetric ones previously available. We find precise agreement between the gravity side and deformed-CFT side results to all orders in the deformation parameter at large central charge. An analysis of the fate of strong subadditivity for relatively boosted regions indicates nonlocality reminiscent of string theory. We introduce the structure of operator algebras in these systems. The causal and entanglement wedges generalize to appropriate deformed theories but exhibit qualitatively new behaviors, e.g. the causal wedge may exceed the entanglement wedge. This leads to subtleties which we express in terms of the Hamiltonian and modular Hamiltonian evolution. Finally, we exhibit redundant encoding of bulk points, including the cosmological case
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