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Holographic entanglement entropy refers to the expression of entanglement entropy of quantum field theories expressed “holographically” via a version of AdS-CFT duality in terms of the geometry of a higher-dimensional bulk spacetime
For quantum field theories that are exhibited as boundary field theories on the asymptotic boundary $A$ of an approximately anti de Sitter spacetime via some approximation to AdS-CFT duality (for instance for QCD via AdS-QCD duality) their entanglement entropy of a given bounded domain $B\subset A$ turns out to be proportional to the area of the minimal-area surface inside the bulk spacetime that has the same boundary $\partial B$ (see Nishioka-Ryu-Takayanagi 09 (3.3) for review of the formula and Lewkowycz-Maldacena 13 for a conceptual explanation).
graphics grabbed from Nishioka-Ryu-Takayanagi 09
This relation is known as the Ryu-Takayanagi formula (Ryu-Takayanagi 06a, Ryu-Takayanagi 06b) for holographic computation of entanglement entropy, or holographic entanglement entropy, for short.
This is a generalization of the proportionality of black hole entropy to the area of its event horizon. Indeed, AdS-CFT duality applies to the near horizon geometry of black branes, the higher-dimensional generalizations of black holes and reduces 4d black holes under suitable KK-compactification (see also at black holes in string theory)
graphics grabbed from Nishioka-Ryu-Takayanagi 09
In fact quantum corrections to the black hole entropy in the presence of matter fields is equal to the entanglement entropy. (Ryu-Takayanagi 06a, p. 13)
Various properties of entanglement entropy find immediate geometric interpretations this way, for instance subadditivity
graphics grabbed from Nishioka-Ryu-Takayanagi 09
Further discussion of implications of the Ryu-Takayanagi formula in van Raamsdonk 10 suggested that the logic may also be turned around: Instead of computing entanglement entropy of a given boundary field theory from known bulk geometry, conversely the bulk spacetime may be reconstructed from knowledge of the entanglement entropy of a boundary field theory.
Talking this perspective to the extreme suggests a description of bulk spacetimes entirely in terms of information theory/entanglement-relations of a boundary QFT (“tensor networks”, Swingle 09, Swingle 12, and quantum error correction codes ADH 14, PYHP 15, see Harlow 18 for review).
graphics grabbed from Harlow 18
graphics grabbed from Harlow 18
In this context the Ryu-Takayanagi formula for holographic entanglement entropy (above) has an exact proof PYHP 15, Theorem 2.
gravitational entropy
The original article are
Shinsei Ryu, Tadashi Takayanagi, Holographic Derivation of Entanglement Entropy from AdS/CFT, Phys. Rev. Lett. 96:181602, 2006 (arXiv:hep-th/0603001)
Shinsei Ryu, Tadashi Takayanagi, Aspects of Holographic Entanglement Entropy, JHEP 0608:045, 2006 (arXiv:hep-th/0605073)
A proposal for a conceptual explanation is made in
Review is in
Survey talks include
Meyers, Holographic entanglement entropy, (pdf slides)
Shinsei Ryu, Holographic geometry in Entanglement Renormalization (pdf slides)
Juan Jottar, (Entanglement) Entropy in three-dimensional higher spin theories (pdf slides)
Matthew Headrick, Entanglement entropies in holographic field theory (pdf slides)
Tadashi Takayanagi, Entanglement Entropy and Holography (Introductory review) (pdf slides)
An influential argument that this relation implies that entanglement in the boundary theory is what makes spacetime as such appear in the bulk theory is due to
Mark Van Raamsdonk, Building up spacetime with quantum entanglement, Gen.Rel.Grav.42:2323-2329,2010; Int.J.Mod.Phys.D19:2429-2435,2010 (arXiv:1005.3035)
Mark Van Raamsdonk, Building up spacetime with quantum entanglement II: It from BC-bit (arXiv:1809.01197)
reviewed in
TASI 2015 Proceedings of the 2015 Theoretical Advanced Study Institute in Elementary Particle Physics 2015 Theoretical Advanced Study Institute in Elementary Particle Physics (arXiv:1609.00026)
Relation to renormalization of entanglement and tensor networks is due to
Brian Swingle, Entanglement Renormalization and Holography (arXiv:0905.1317)
Brian Swingle, Constructing holographic spacetimes using entanglement renormalization (arXiv:1209.3304)
and further in terms of quantum error correcting codes due to
Ahmed Almheiri, Xi Dong, Daniel Harlow, Bulk Locality and Quantum Error Correction in AdS/CFT, JHEP 1504:163,2015 (arXiv:1411.7041)
Fernando Pastawski, Beni Yoshida, Daniel Harlow, John Preskill, Holographic quantum error-correcting codes: Toy models for the bulk/boundary correspondence, JHEP 06 (2015) 149 (arXiv:1503.06237)
reviewed in
Further debelopment of these tensor networks in
Computation of black hole entropy in 4d via AdS4-CFT3 duality from holographic entanglement entropy in the ABJM theory for the M2-brane is discussed in
Last revised on May 17, 2019 at 13:46:38. See the history of this page for a list of all contributions to it.