Bulk locality and asymptotic causal diamonds

In AdS/CFT, the non-uniqueness of the reconstructed bulk from boundary subregions has motivated the notion of code subspaces. We present some closely related structures that arise in flat space. A useful organizing idea is that of an $asymptotic$ causal diamond (ACD): a causal diamond attached to...

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Main Author: Chethan Krishnan
Format: Article
Language:English
Published: SciPost 2019-10-01
Series:SciPost Physics
Online Access:https://scipost.org/SciPostPhys.7.4.057
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author Chethan Krishnan
author_facet Chethan Krishnan
author_sort Chethan Krishnan
collection DOAJ
description In AdS/CFT, the non-uniqueness of the reconstructed bulk from boundary subregions has motivated the notion of code subspaces. We present some closely related structures that arise in flat space. A useful organizing idea is that of an $asymptotic$ causal diamond (ACD): a causal diamond attached to the conformal boundary of Minkowski space. The space of ACDs is defined by pairs of points, one each on the future and past null boundaries, ${\cal I}^{\pm}$. We observe that for flat space with an IR cut-off, this space (a) encodes a preferred class of boundary subregions, (b) is a plausible way to capture holographic data for local bulk reconstruction, (c) has a natural interpretation as the kinematic space for holography, (d) leads to a holographic entanglement entropy in flat space that matches previous definitions and satisfies strong sub-additivity, and, (e) has a bulk union/intersection structure isomorphic to the one that motivated the introduction of quantum error correction in AdS/CFT. By sliding the cut-off, we also note one substantive way in which flat space holography differs from that in AdS. Even though our discussion is centered around flat space (and AdS), we note that there are notions of ACDs in other spacetimes as well. They could provide a covariant way to abstractly characterize tensor sub-factors of Hilbert spaces of holographic theories.
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spelling doaj.art-902ed2a645b749e0b6c5019ceb5750792022-12-21T23:55:25ZengSciPostSciPost Physics2542-46532019-10-017405710.21468/SciPostPhys.7.4.057Bulk locality and asymptotic causal diamondsChethan KrishnanIn AdS/CFT, the non-uniqueness of the reconstructed bulk from boundary subregions has motivated the notion of code subspaces. We present some closely related structures that arise in flat space. A useful organizing idea is that of an $asymptotic$ causal diamond (ACD): a causal diamond attached to the conformal boundary of Minkowski space. The space of ACDs is defined by pairs of points, one each on the future and past null boundaries, ${\cal I}^{\pm}$. We observe that for flat space with an IR cut-off, this space (a) encodes a preferred class of boundary subregions, (b) is a plausible way to capture holographic data for local bulk reconstruction, (c) has a natural interpretation as the kinematic space for holography, (d) leads to a holographic entanglement entropy in flat space that matches previous definitions and satisfies strong sub-additivity, and, (e) has a bulk union/intersection structure isomorphic to the one that motivated the introduction of quantum error correction in AdS/CFT. By sliding the cut-off, we also note one substantive way in which flat space holography differs from that in AdS. Even though our discussion is centered around flat space (and AdS), we note that there are notions of ACDs in other spacetimes as well. They could provide a covariant way to abstractly characterize tensor sub-factors of Hilbert spaces of holographic theories.https://scipost.org/SciPostPhys.7.4.057
spellingShingle Chethan Krishnan
Bulk locality and asymptotic causal diamonds
SciPost Physics
title Bulk locality and asymptotic causal diamonds
title_full Bulk locality and asymptotic causal diamonds
title_fullStr Bulk locality and asymptotic causal diamonds
title_full_unstemmed Bulk locality and asymptotic causal diamonds
title_short Bulk locality and asymptotic causal diamonds
title_sort bulk locality and asymptotic causal diamonds
url https://scipost.org/SciPostPhys.7.4.057
work_keys_str_mv AT chethankrishnan bulklocalityandasymptoticcausaldiamonds