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Radiation, entanglement and islands from a boundary local quench

by Lorenzo Bianchi, Stefano De Angelis, Marco Meineri

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Submission summary

Authors (as registered SciPost users): Lorenzo Bianchi · Stefano De Angelis · Marco Meineri
Submission information
Preprint Link:  (pdf)
Date accepted: 2023-04-06
Date submitted: 2023-02-07 20:12
Submitted by: De Angelis, Stefano
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • High-Energy Physics - Theory
Approach: Theoretical


We study the entanglement and the energy density of the radiation emitted after a local quench in a boundary conformal field theory. We use the operator product expansion (OPE) to predict the early- and late-time behavior of the entanglement entropy and we find, under mild assumptions, a universal form for the leading term, which we test on some treatable two-dimensional examples. We also derive a general upper bound on the entanglement, valid along the full time evolution. In two dimensions, the bound is computed analytically, while in higher dimensions it is evaluated at early and late time via the OPE. These CFT predictions are then compared with a doubly-holographic setup where the CFT is interpreted as a reservoir for the radiation produced on an end-of-the-world brane. After finding the gravitational dual of a boundary local quench, we compute the time evolution of the holographic entanglement entropy, whose late-time behavior is in perfect agreement with the CFT predictions. In the brane+bath picture, unitarity of the time evolution is preserved thanks to the formation of an island. The holographic results can be recovered explicitly from the island formula, in the limit where the tension of the brane is close to the maximal value.

Published as SciPost Phys. 14, 148 (2023)

Reports on this Submission

Anonymous Report 1 on 2023-2-8 (Invited Report)


The authors have added the clarifying comments I requested (and much more). I am now happy to recommend the paper for publication.

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