A physical protocol for  observers near the boundary to obtain bulk information in quantum gravity

Chowdhury, Chandramouli; Papadoulaki, Olga; Raju, Suvrat

doi:10.21468/scipostphys.10.5.106

Cited by 48 publications

(73 citation statements)

References 46 publications

(85 reference statements)

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“…. For an operator φ ∈ A E that is not in the causal wedge and a local boundary operator O ∈ A, we know from bulk causality that O cannot detect a φ insertion to leading order in G N , 23 ∀O ∈ A, ψ e −i φ Oe i φ ψ ≈ ψ|O|ψ .…”

Section: Connection Between Bulk and Boundary Cocycle Flowmentioning

confidence: 99%

Seeing the entanglement wedge

Levine

Shahbazi-Moghaddam

Soni³

2021

J. High Energ. Phys.

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We study the problem of revealing the entanglement wedge using simple operations. We ask what operation a semiclassical observer can do to bring the entanglement wedge into causal contact with the boundary, via backreaction.In a generic perturbative class of states, we propose a unitary operation in the causal wedge whose backreaction brings all of the previously causally inaccessible ‘peninsula’ into causal contact with the boundary. This class of cases includes entanglement wedges associated to boundary sub-regions that are unions of disjoint spherical caps, and the protocol works to first order in the size of the peninsula. The unitary is closely related to the so-called Connes Cocycle flow, which is a unitary that is both well-defined in QFT and localised to a sub-region. Our construction requires a generalization of the work by Ceyhan & Faulkner to regions which are unions of disconnected spherical caps. We discuss this generalization in the appendix. We argue that this cocycle should be thought of as naturally generalizing the non-local coupling introduced in the work of Gao, Jafferis & Wall.

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Section: Connection Between Bulk and Boundary Cocycle Flowmentioning

confidence: 99%

Seeing the entanglement wedge

Levine

Shahbazi-Moghaddam

Soni³

2021

J. High Energ. Phys.

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“…However, this is forbidden in any quantum system undergoing a unitary time evolution [6]. The recent resolution to this puzzle has revealed a novel formula for the fine-grained entropy of the Hawking radiation which involves extremization over regions in black hole spacetime known as the "Islands" (1) 1 A different approach towards the resolution to the information loss puzzle has been explored in [11,12]. According to this approach, a copy of the information inside the black hole is always available outside and hence the Page curve is trivial ( See [13] for a recent review.)…”

Section: Introductionmentioning

confidence: 99%

Islands for entanglement negativity

et al. 2022

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We advance two alternative proposals for the island contributions to the entanglement negativity of various pure and mixed state configurations in quantum field theories coupled to semiclassical gravity. The first construction involves the extremization of an algebraic sum of the generalized Renyi entropies of order half. The second proposal involves the extremization of the sum of the effective entanglement negativity of quantum matter fields and the backreacted area of a cosmic brane spanning the entanglement wedge cross section which also extremizes the generalized Renyi reflected entropy of order half. These proposals are utilized to obtain the island contributions to the entanglement negativity of various pure and mixed state configurations involving the bath systems coupled to extremal and non-extremal black holes in JT gravity demonstrating an exact match with each other. Furthermore, the results from both the proposals match precisely with the island contribution to half the Renyi reflected entropy of order half providing a strong consistency check. We then allude to a possible doubly holographic picture of our island proposals and provide a derivation of the first proposal by determining the corresponding replica wormhole contributions.

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“…Roughly speaking, we can view the effective entropy as the entropy of a "conditional state" of low energy degrees of freedom, with the condition that a classical background geometry is observed by a family of observers in the bath region. It is unclear to the author how this discussion will be modified if we more rigorously taken into account the nonlocality of quantum gravity Hilbert space [43][44][45][46]. For example, we notice that ref.…”

Section: Jhep01(2022)085mentioning

confidence: 99%

Entanglement island, miracle operators and the firewall

2022

J. High Energ. Phys.

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In this paper, we obtain some general results on information retrieval from the black hole interior, based on the recent progress on quantum extremal surface formula and entanglement island. We study an AdS black hole coupled to a bath with generic dynamics, and ask whether it is possible to retrieve information about a small perturbation in the interior from the bath system. We show that the one-norm distance between two reduced states in a bath region A is equal to the same quantity in the bulk quantum field theory for region AI where I is the entanglement island of A. This is a straightforward generalization of bulk-boundary correspondence in AdS/CFT. However, we show that a contradiction arises if we apply this result to a special situation when the bath dynamics includes a unitary operation that carries a particular measurement to a region A and send the result to another region W. Physically, the contradiction arises between transferability of classical information during the measurement, and non-transferability of quantum information which determines the entanglement island.We propose that the resolution of the contradiction is to realize that the state reconstruction formula does not apply to the special situation involving interior-information-retrieving measurements. This implies that the assumption of smooth replica AdS geometry with boundary condition set by the flat space bath has to break down when the particular measurement operator is applied to the bath. Using replica trick, we introduce an explicitly construction of such operator, which we name as “miracle operators”. From this construction we see that the smooth replica geometry assumption breaks down because we have to introduce extra replica wormholes connecting with the “simulated blackholes” introduced by the miracle operator. We study the implication of miracle operators in understanding the firewall paradox.

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A physical protocol for observers near the boundary to obtain bulk information in quantum gravity

Cited by 48 publications

References 46 publications

Seeing the entanglement wedge

Seeing the entanglement wedge

Islands for entanglement negativity

Entanglement island, miracle operators and the firewall

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