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REVIEW 3 major objections 3 minor 111 references

After the Page time, the correct Page curve for an eternal black hole appears precisely when either two exterior regions lose all mutual information or the island and radiation become infinitely entangled; the two conditions are equivalent

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

T0 review · grok-4.5

2026-07-11 14:49 UTC pith:DHV2YGNC

load-bearing objection Clean incremental observation: the same scrambling-time locus that kills I(B+:B−) makes I(I:R) diverge, plus a usable closed form for the tripartite I(I:R+:R−), all inside pure eternal JT. the 3 major comments →

arxiv 2607.04706 v1 pith:DHV2YGNC submitted 2026-07-06 hep-th

New insights on mutual information in the island approach to the Page curve

classification hep-th
keywords Page curveisland formulamutual informationtripartite informationeternal black holeJackiw-Teitelboim gravityscrambling timegeometric entanglement
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper argues that the post-Page-time Page curve of an eternal black hole is controlled by how mutual information is shared among regions on a single Cauchy slice. Earlier work showed that the mutual information between the two exterior intervals B+ and B- vanishes at scrambling time, producing a time-independent matter entropy and thereby the flat Page curve. The new observation is that the identical time condition forces the mutual information between the island and the full radiation region to diverge, so the island and radiation become maximally entangled. The authors interpret this as a conservation of geometric entanglement: when one bipartition disconnects, another becomes infinitely correlated. They also derive an explicit formula for the tripartite mutual information among the island and the two radiation halves, finding it always negative and therefore monogamous.

Core claim

Reproducing the expected Page curve after the Page time requires that either I(B+:B-)=0 or I(I:R) o infinity; these two conditions are mathematically equivalent under the pure-state property of the Cauchy slice and together rewrite the island formula so that the matter-entropy term becomes time-independent.

What carries the argument

The rewritten island formula that replaces the matter entropy S(I\cup R) by the entropy of B+\cup B- evaluated either at vanishing I(B+:B-) or at divergent I(I:R). The explicit expression for I(I:R) diverges exactly when ta-tb equals the absolute difference of tortoise coordinates of the island and radiation endpoints.

Load-bearing premise

The full Cauchy slice that contains the island, the radiation, and the complementary exterior regions must be in a pure quantum state, so the entropy of island-plus-radiation equals the entropy of the complementary pair of exterior intervals.

What would settle it

In any concrete model where the global state on the Cauchy slice is mixed (or the island and radiation do not exhaust a pure slice), compute both mutual informations at the putative scrambling time and check whether vanishing of one still forces divergence of the other and still yields a flat post-Page entropy.

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • The Page curve can be obtained by demanding infinite island-radiation mutual information instead of vanishing exterior mutual information.
  • Geometric correlations on a Cauchy slice are conserved: loss of correlation in one bipartition is compensated by maximal entanglement in another.
  • The tripartite information I(I:R+:R-) is always negative, so island degrees of freedom are encoded nonlocally across both radiation halves rather than redundantly in either half alone.
  • The same pair of equivalent conditions may determine the Page curve for evaporating black holes once the calculation is extended beyond the eternal case.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If the conservation relation survives in dynamical evaporating geometries, one could track the Page curve solely through the growth of I(I:R) without repeatedly locating quantum extremal surfaces.
  • The observed monogamy of I(I:R+:R-) implies that partial access to only one radiation half cannot reconstruct the island, a multipartite security feature that may be testable in toy qubit models of black-hole evaporation.
  • The divergence of I(I:R) at scrambling time offers a diagnostic for the onset of replica-wormhole dominance that is independent of the area term in the island formula.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

3 major / 3 minor

Summary. The paper studies mutual information for subsystems on a Cauchy slice in the island approach to the Page curve of an eternal black hole in JT gravity with a flat thermal bath. Building on the authors’ earlier results that I(B+:B−) vanishes at the scrambling time ta−tb=|r∗(a)−r∗(b)| (yielding a time-independent matter entropy and the correct post-Page Page curve), it shows that the identical geometric condition makes I(I:R) diverge. This is interpreted as conservation of geometric correlation among regions on the slice. Using free-CFT entropy formulas and purity of the full Cauchy slice, the authors also derive a closed-form expression for the tripartite mutual information I(I:R+:R−), demonstrate that it is always negative (monogamous/superextensive), and plot its dependence on island and observer times.

Significance. The dual conditions I(B+:B−)=0 or I(I:R)→∞ give an alternative phrasing of the island contribution that produces the Page curve and may be useful for evaporating black holes (as the authors suggest). The explicit tripartite formula and its monogamy property are a concrete new result in the island literature, obtained cleanly from standard Calabrese–Cardy distance formulas and Cauchy-slice purity. The algebraic steps are elementary and transparent. The work is incremental relative to the authors’ prior series, so overall novelty is moderate, but the multipartite perspective is a welcome addition if the claims are carefully stated.

major comments (3)
  1. [Section III, eqs. (22)–(30) and claim (2)] The claimed equivalence of I(B+:B−)=0 and I(I:R)→∞ (eq. (2)) and the rewritten island formula (30) rest entirely on the pure-state identity S_vN(I∪R)=S_vN(B+∪B−) used after eq. (22) and again for (23) and (30). This identity is valid inside the eternal pure-state setup, but the ‘conservation of geometric correlation’ is then essentially a rewriting of that identity rather than an independent principle. The purity assumption must be stated explicitly, and the manuscript should clarify that the two conditions share the same critical surface only because of it; otherwise the central interpretive claim overreaches.
  2. [Section IV, eq. (47) and Fig. 3] Eq. (47) for I(I:R+:R−) depends only on ta, a and the outer endpoint e (with te apparently fixed at 0); it is independent of observer time tb and of b. Fig. 3b nevertheless plots the same quantity versus tb (fixed b=10 r+). This is inconsistent. Either the analytic expression must be corrected to include the times of e±, an unstated relation (e.g., te=tb or ta−tb fixed) must be specified for the plot, or the figure must be replaced. In addition, the outer points e± are never defined in the text or shown in Fig. 2, yet they control both the formula and the numerical values in Fig. 3.
  3. [Abstract, Introduction and Conclusion] The language of ‘conservation of geometrical entanglement’ and ‘deep insights about the conservation of geometrical entanglement’ (abstract, Introduction, Conclusion) is not supported by any quantitative conservation law (no relation such as a sum or product of mutual informations remaining constant is derived). The actual observation is that the same geometric locus makes one mutual information vanish and the other diverge. The claims should be rephrased more precisely to ‘complementary behaviour under the scrambling-time condition’ or equivalent.
minor comments (3)
  1. [Throughout] Numerous formatting artifacts appear throughout (e.g., ‘COMPUT A TION’, ‘GRA VITY’, ‘INFORMA TION’) together with minor typos (Conclusion: ‘I(R+:R−) diverges’ should read I(I:R); stray capitalisation such as ‘An important observation’). These should be cleaned for the final version.
  2. [Fig. 2 and Section IV] The outer endpoints e± of the radiation regions R± should be indicated on the Penrose diagram (Fig. 2) and defined in the text at first use, since they enter the tripartite formula and the plots.
  3. [References and Introduction] The paper relies heavily on the authors’ own prior works [86–90] for the Page-curve interpretation. A more balanced discussion of the broader island literature would improve the presentation.

Circularity Check

2 steps flagged

Page-curve interpretation of the shared critical surface rests on self-cited prior works; the new divergence and tripartite formulas are independently computed algebra under the model's purity assumption.

specific steps
  1. self citation load bearing [Abstract; Introduction (paragraphs after eq. (1)); rewritten island formula (30)]
    "In our earlier works, we have shown how the saturation of mutual information between two specific subsystems plays a vital role in obtaining the correct Page curve for the eternal black hole. In those works, we have shown that the mutual information between B+ and B−, that is, I(B+:B−), vanishes at scrambling time, which leads to the correct Page curve. ... = min ext_I {A(∂I)/4GN + S_vN(B+∪B−)|I(B+:B−)=0} = min ext_I {A(∂I)/4GN + S_vN(B+∪B−)|I(I:R)→∞}."

    The physical claim that vanishing I(B+:B−) (or the newly observed divergence of I(I:R)) yields the correct Page curve is justified solely by citation to the authors' own prior papers [86–90]. The present algebra shows only that the two mutual informations share the same critical surface; the Page-curve interpretation of that surface is imported by self-citation and is load-bearing for the strongest claim (eqs. (2) and (30)).

  2. other [Section III, eqs. (21), (28)–(29) and the purity step after (22)]
    "ta−tb=|r∗(a)−r∗(b)|. ... I(B+:B−)|ta−tb=|r∗(a)−r∗(b)|=0. ... I(I:R)|ta−tb=|r∗(a)−r∗(b)|→∞. ... from the pure state property of the von-Neumann entropy, we can write SvN(I∪R)=SvN(B+∪B−)."

    Once purity is used to replace S(I∪R) by S(B+∪B−), the identical geometric locus that nullifies the numerator/denominator combination in I(B+:B−) automatically sends the denominator of I(I:R) to zero. The claimed 'equivalence' and 'conservation of geometric correlation' therefore hold by construction inside the pure-state model; they are not an independent dynamical prediction.

full rationale

The paper's new algebraic results (explicit formula for I(I:R) in (26)–(27), its divergence under the geometric locus (29), and the tripartite expression (44)–(47)) are derived from standard 2d CFT distance formulas and the pure-state identity S(I∪R)=S(B+∪B−) that is native to the eternal JT+bath setup. These steps do not reduce to fitted parameters or to a definitional tautology. The interpretive claim that either I(B+:B−)=0 or I(I:R)→∞ is necessary and sufficient for the correct post-Page Page curve (eqs. (2), (30)) does, however, import its physical meaning wholesale from the authors' earlier series [86–90]. That is ordinary self-citation of prior results rather than a uniqueness theorem or an ansatz smuggled by citation, so the circularity burden remains modest. No fitted-input-as-prediction or renaming-of-known-result patterns appear. Score 3 reflects one load-bearing self-citation chain that is not the sole content of the paper.

Axiom & Free-Parameter Ledger

0 free parameters · 4 axioms · 0 invented entities

The paper works entirely within the standard island-formula and free-2d-CFT toolkit. No free parameters are fitted; the only inputs are the JT metric, the free-CFT entropy formulas, and the pure-state property of a Cauchy slice. No new entities are postulated.

axioms (4)
  • domain assumption Von Neumann entropy of free 2d CFT intervals is given by the Calabrese–Cardy logarithmic distance formulas (eqs. (13), (24), (25), (36)–(39)).
    Invoked throughout §§III–IV; standard but essential for every explicit expression.
  • domain assumption The full Cauchy slice is in a pure state, so S(I∪R)=S(B+∪B−).
    Used immediately after eq. (22) and again to obtain eq. (43); without it the mutual-information identities collapse.
  • domain assumption The island formula (1) correctly computes the fine-grained entropy of Hawking radiation.
    Background assumption of the entire program; not re-derived here.
  • ad hoc to paper The geometric condition ta−tb=|r∗(a)−r∗(b)| is the scrambling time at which I(B+:B−) vanishes.
    Taken from the authors’ earlier series and re-used as the trigger for the new divergence claim.

pith-pipeline@v1.1.0-grok45 · 23385 in / 2484 out tokens · 23722 ms · 2026-07-11T14:49:53.692873+00:00 · methodology

0 comments
read the original abstract

In this article, we have presented one of the very important observations, regarding the behavior of mutual information of two different sets of subsystems in the after Page time scenario. This provides us with some deep insights about the conservation of geometrical entanglement. In our earlier works, we have shown how the saturation of mutual information between two specific subsystems plays a vital role in obtaining the correct Page curve for the eternal black hole. In those works, we have shown that the mutual information between $B_+$ and $B_-$, that is, $I(B_{+}: B_{-})$, vanishes at scrambling time, which leads to the correct Page curve. That means that at scrambling time, there is no correlation between $B_+$ and $B_-$. Remarkably, it is observed that at this particular value of observer's time, the mutual information between $\mathcal{I}$ and $R$, that is, $I(\mathcal{I}:R)$, becomes infinity. This indicates that the regions $\mathcal{I}$ and $R$ become maximally entangled. This provides us with a notion of conservation of geometric correlation between different regions on the Cauchy slice. In this work, we have also provided a way to calculate the tripartite mutual information of regions $\mathcal{I}$,$R_+$ and $R_-$, that is, $I(\mathcal{I}:R_+:R_-)$ on the Cauchy slice using the earlier results involving the bipartite regions. This is a new result which was missing in the earlier literature.

Figures

Figures reproduced from arXiv: 2607.04706 by Anirban Roy Chowdhury, Souvik Paul, Sunandan Gangopadhyay.

Figure 1
Figure 1. Figure 1: FIG. 1: Penrose diagram of an eternal black hole in JT [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: Penrose diagram of an eternal black hole in [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: The left panel shows the variation of the tripartite information between [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗

discussion (0)

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Reference graph

Works this paper leans on

111 extracted references · 91 linked inside Pith

  1. [1]

    Particle Creation by Black Holes

    S. W. Hawking, “Particle Creation by Black Holes”, Commun. Math. Phys.43(1975) 199, [Erratum: Com- mun.Math.Phys. 46, 206 (1976)]

  2. [2]

    Breakdown of predictability in gravi- tational collapse

    S. W. Hawking, “Breakdown of predictability in gravi- tational collapse”,Phys. Rev. D14(1976) 2460

  3. [3]

    Black holes and thermodynamics

    S. W. Hawking, “Black holes and thermodynamics”, Phys. Rev. D13(1976) 191

  4. [4]

    Information in black hole radiation

    D. N. Page, “Information in black hole radiation”,Phys. Rev. Lett.71(1993) 3743

  5. [5]

    Black holes and entropy

    J. D. Bekenstein, “Black holes and entropy”,Phys. Rev. D7(1973) 2333

  6. [6]

    Time dependence of Hawking radiation en- tropy

    D. N. Page, “Time dependence of Hawking radiation en- tropy”,Journal of Cosmology and Astroparticle Physics 2013[09](2013) 028

  7. [7]

    Black Holes: Complementarity or Firewalls?

    A. Almheiri, D. Marolf, J. Polchinski and J. Sully, “Black Holes: Complementarity or Firewalls?”,JHEP 02(2013) 062,arXiv:1207.3123 [hep-th]

  8. [8]

    The LargeNlimit of superconfor- mal field theories and supergravity

    J. M. Maldacena, “The LargeNlimit of superconfor- mal field theories and supergravity”,Adv. Theor. Math. Phys.2(1998) 231,arXiv:hep-th/9711200

  9. [9]

    Anti de Sitter space and hologra- phy

    E. Witten, “Anti de Sitter space and hologra- phy”,Adv. Theor. Math. Phys.2(1998) 253, arXiv:hep-th/9802150

  10. [10]

    Large N field theories, string the- ory and gravity

    O. Aharony, S. S. Gubser, J. M. Maldacena, H. Ooguri and Y. Oz, “Large N field theories, string the- ory and gravity”,Phys. Rept.323(2000) 183, arXiv:hep-th/9905111

  11. [11]

    Islands outside the horizon

    A. Almheiri, R. Mahajan and J. Maldacena, “Islands outside the horizon”,arXiv:1910.11077 [hep-th]

  12. [12]

    Replica wormholes and the black hole interior

    G. Penington, S. H. Shenker, D. Stanford and Z. Yang, “Replica wormholes and the black hole interior”,JHEP 03(2022) 205,arXiv:1911.11977 [hep-th]

  13. [13]

    Entanglement Wedge Reconstruction and the Information Paradox

    G. Penington, “Entanglement Wedge Reconstruction and the Information Paradox”,JHEP09(2020) 002, arXiv:1905.08255 [hep-th]

  14. [14]

    The Page curve of Hawking radiation from semiclassi- cal geometry

    A. Almheiri, R. Mahajan, J. Maldacena and Y. Zhao, “The Page curve of Hawking radiation from semiclassi- cal geometry”,JHEP03(2020) 149,arXiv:1908.10996 [hep-th]

  15. [15]

    Quantum Extremal Surfaces: Holographic Entanglement Entropy be- yond the Classical Regime

    N. Engelhardt and A. C. Wall, “Quantum Extremal Surfaces: Holographic Entanglement Entropy be- yond the Classical Regime”,JHEP01(2015) 073, arXiv:1408.3203 [hep-th]

  16. [16]

    A Covariant holographic entanglement entropy proposal

    V. E. Hubeny, M. Rangamani and T. Takayanagi, “A Covariant holographic entanglement entropy proposal”, JHEP07(2007) 062,arXiv:0705.0016 [hep-th]

  17. [17]

    Holographic Deriva- tion of Entanglement Entropy from the anti–de Sitter Space/Conformal Field Theory Correspondence

    S. Ryu and T. Takayanagi, “Holographic Deriva- tion of Entanglement Entropy from the anti–de Sitter Space/Conformal Field Theory Correspondence”,Phys. Rev. Lett.96(2006) 181602

  18. [18]

    Replica Wormholes and the En- tropy of Hawking Radiation

    A. Almheiri, T. Hartman, J. Maldacena, E. Shaghou- lian and A. Tajdini, “Replica Wormholes and the En- tropy of Hawking Radiation”,JHEP05(2020) 013, arXiv:1911.12333 [hep-th]

  19. [19]

    Replica worm- holes for an evaporating 2D black hole

    K. Goto, T. Hartman and A. Tajdini, “Replica worm- holes for an evaporating 2D black hole”,JHEP04 (2021) 289,arXiv:2011.09043 [hep-th]

  20. [20]

    Real-time gravitational replicas: For- malism and a variational principle

    S. Colin-Ellerin, X. Dong, D. Marolf, M. Rangamani and Z. Wang, “Real-time gravitational replicas: For- malism and a variational principle”,JHEP05(2021) 117,arXiv:2012.00828 [hep-th]

  21. [21]

    The entropy of Hawking ra- diation

    A. Almheiri, T. Hartman, J. Maldacena, E. Shaghou- lian and A. Tajdini, “The entropy of Hawking ra- diation”,Rev. Mod. Phys.93[3](2021) 035002, arXiv:2006.06872 [hep-th]

  22. [22]

    Information flow in black hole evaporation

    H. Z. Chen, Z. Fisher, J. Hernandez, R. C. Myers and S.- M. Ruan, “Information flow in black hole evaporation”, Journal of High Energy Physics2020[3](2020) 1

  23. [23]

    Effective entropy of quantum fields coupled with gravity

    X. Dong, X.-L. Qi, Z. Shangnan and Z. Yang, “Effective entropy of quantum fields coupled with gravity”,JHEP 10(2020) 052,arXiv:2007.02987 [hep-th]

  24. [24]

    Notes on islands in asymp- totically flat 2d dilaton black holes

    T. Anegawa and N. Iizuka, “Notes on islands in asymp- totically flat 2d dilaton black holes”,JHEP07(2020) 036,arXiv:2004.01601 [hep-th]. 10

  25. [25]

    Is- lands in de Sitter space

    V. Balasubramanian, A. Kar and T. Ugajin, “Is- lands in de Sitter space”,JHEP02(2021) 072, arXiv:2008.05275 [hep-th]

  26. [26]

    Lessons from the information paradox

    S. Raju, “Lessons from the information paradox”,Phys. Rept.943(2022) 1,arXiv:2012.05770 [hep-th]

  27. [27]

    Island in the presence of higher derivative terms

    M. Alishahiha, A. Faraji Astaneh and A. Naseh, “Island in the presence of higher derivative terms”,JHEP02 (2021) 035,arXiv:2005.08715 [hep-th]

  28. [28]

    Is- lands in flat-space cosmology

    S. Azarnia, R. Fareghbal, A. Naseh and H. Zolfi, “Is- lands in flat-space cosmology”,Phys. Rev. D104[12] (2021) 126017,arXiv:2109.04795 [hep-th]

  29. [29]

    A Note on Islands in Schwarzschild Black Holes

    I. Aref’eva and I. Volovich, “A Note on Islands in Schwarzschild Black Holes”,arXiv:2110.04233 [hep-th]

  30. [30]

    The univer- sality of islands outside the horizon

    S. He, Y. Sun, L. Zhao and Y.-X. Zhang, “The univer- sality of islands outside the horizon”,JHEP05(2022) 047,arXiv:2110.07598 [hep-th]

  31. [31]

    Entropy of Hawking radiation for two-sided hyperscaling violating black branes

    F. Omidi, “Entropy of Hawking radiation for two-sided hyperscaling violating black branes”,JHEP04(2022) 022,arXiv:2112.05890 [hep-th]

  32. [32]

    Is- land, Page curve, and superradiance of rotating BTZ black holes

    M.-H. Yu, C.-Y. Lu, X.-H. Ge and S.-J. Sin, “Is- land, Page curve, and superradiance of rotating BTZ black holes”,Phys. Rev. D105[6](2022) 066009, arXiv:2112.14361 [hep-th]

  33. [33]

    Page Curves of Reissner-Nordstr¨ om Black Hole in HD Gravity

    G. Yadav, “Page Curves of Reissner-Nordstr¨ om Black Hole in HD Gravity”,arXiv:2204.11882 [hep-th]

  34. [34]

    Uni- tary Constraints on Semiclassical Schwarzschild Black Holes in the Presence of Island

    D.-H. Du, W.-C. Gan, F.-W. Shu and J.-R. Sun, “Uni- tary Constraints on Semiclassical Schwarzschild Black Holes in the Presence of Island”,arXiv:2206.10339 [hep-th]

  35. [35]

    Islands and Page Curves for Evaporating Black Holes in JT Gravity

    T. J. Hollowood and S. P. Kumar, “Islands and Page Curves for Evaporating Black Holes in JT Gravity”, JHEP08(2020) 094,arXiv:2004.14944 [hep-th]

  36. [36]

    Is- lands in Asymptotically Flat 2D Gravity

    T. Hartman, E. Shaghoulian and A. Strominger, “Is- lands in Asymptotically Flat 2D Gravity”,JHEP07 (2020) 022,arXiv:2004.13857 [hep-th]

  37. [37]

    Page curves for a fam- ily of exactly solvable evaporating black holes

    X. Wang, R. Li and J. Wang, “Page curves for a fam- ily of exactly solvable evaporating black holes”,Phys. Rev. D103[12](2021) 126026,arXiv:2104.00224 [hep-th]

  38. [38]

    Island may not save the information paradox of Liouville black holes

    R. Li, X. Wang and J. Wang, “Island may not save the information paradox of Liouville black holes”,Phys. Rev. D104[10](2021) 106015,arXiv:2105.03271 [hep-th]

  39. [39]

    Semi-classical thermodynamics of quantum extremal surfaces in Jackiw-Teitelboim gravity

    J. F. Pedraza, A. Svesko, W. Sybesma and M. R. Visser, “Semi-classical thermodynamics of quantum extremal surfaces in Jackiw-Teitelboim gravity”,JHEP12(2021) 134,arXiv:2107.10358 [hep-th]

  40. [40]

    Entangle- ment islands in higher dimensions

    A. Almheiri, R. Mahajan and J. E. Santos, “Entangle- ment islands in higher dimensions”,SciPost Phys.9[1] (2020) 001,arXiv:1911.09666 [hep-th]

  41. [41]

    Islands and stretched horizon

    Y. Matsuo, “Islands and stretched horizon”,JHEP07 (2021) 051,arXiv:2011.08814 [hep-th]

  42. [42]

    Critical Islands

    C. Krishnan, “Critical Islands”,JHEP01(2021) 179, arXiv:2007.06551 [hep-th]

  43. [43]

    Page Curve and the Information Paradox in Flat Space

    C. Krishnan, V. Patil and J. Pereira, “Page Curve and the Information Paradox in Flat Space”, arXiv:2005.02993 [hep-th]

  44. [44]

    Small Schwarzschild de Sitter black holes, quantum extremal surfaces and islands

    K. Goswami and K. Narayan, “Small Schwarzschild de Sitter black holes, quantum extremal surfaces and islands”,JHEP10(2022) 031,arXiv:2207.10724 [hep-th]

  45. [45]

    Island in Charged Black Holes

    Y. Ling, Y. Liu and Z.-Y. Xian, “Island in Charged Black Holes”,JHEP03(2021) 251,arXiv:2010.00037 [hep-th]

  46. [46]

    Entanglement entropy of asymp- totically flat non-extremal and extremal black holes with an island

    W. Kim and M. Nam, “Entanglement entropy of asymp- totically flat non-extremal and extremal black holes with an island”,Eur. Phys. J. C81[10](2021) 869, arXiv:2103.16163 [hep-th]

  47. [47]

    Islands in charged linear dilaton black holes

    B. Ahn, S.-E. Bak, H.-S. Jeong, K.-Y. Kim and Y.- W. Sun, “Islands in charged linear dilaton black holes”, Phys. Rev. D105[4](2022) 046012,arXiv:2107.07444 [hep-th]

  48. [48]

    Islands and complexity of eternal black hole and radiation subsystems for a doubly holographic model

    A. Bhattacharya, A. Bhattacharyya, P. Nandy and A. K. Patra, “Islands and complexity of eternal black hole and radiation subsystems for a doubly holographic model”,JHEP05(2021) 135,arXiv:2103.15852 [hep-th]

  49. [49]

    Bra-ket wormholes in gravitationally prepared states

    Y. Chen, V. Gorbenko and J. Maldacena, “Bra-ket wormholes in gravitationally prepared states”,JHEP 02(2021) 009,arXiv:2007.16091 [hep-th]

  50. [50]

    Effect of backreac- tion on island, Page curve and mutual information

    P. Jain, S. Pant and H. Parihar, “Effect of backreac- tion on island, Page curve and mutual information”, Nucl. Phys. B1018(2025) 116991,arXiv:2311.08186 [hep-th]

  51. [51]

    Page curves on codim-m and charged branes

    Y. Guo and R.-X. Miao, “Page curves on codim-m and charged branes”,Eur. Phys. J. C83[9](2023) 847

  52. [52]

    Is- land formula in Planck brane

    J.-C. Chang, S. He, Y.-X. Liu and L. Zhao, “Is- land formula in Planck brane”,JHEP11(2023) 006, arXiv:2308.03645 [hep-th]

  53. [53]

    Massless entanglement is- lands in cone holography

    D. Li and R.-X. Miao, “Massless entanglement is- lands in cone holography”,JHEP06(2023) 056, arXiv:2303.10958 [hep-th]

  54. [54]

    Page curves and entanglement islands for the step-function Vaidya model of evaporating black holes

    C.-Z. Guo, W.-C. Gan and F.-W. Shu, “Page curves and entanglement islands for the step-function Vaidya model of evaporating black holes”,JHEP05(2023) 042, arXiv:2302.02379 [hep-th]

  55. [55]

    Entanglement island and Page curve in wedge holography

    R.-X. Miao, “Entanglement island and Page curve in wedge holography”,JHEP03(2023) 214, arXiv:2301.06285 [hep-th]

  56. [56]

    Cosmological and black hole islands in multi-event horizon spacetimes

    G. Yadav and N. Joshi, “Cosmological and black hole islands in multi-event horizon spacetimes”,Phys. Rev. D107[2](2023) 026009,arXiv:2210.00331 [hep-th]

  57. [57]

    Planar black holes in holographic axion gravity: Islands, Page times, and scrambling times

    S. A. Hosseini Mansoori, O. Luongo, S. Mancini, M. Mirjalali, M. Rafiee and A. Tavanfar, “Planar black holes in holographic axion gravity: Islands, Page times, and scrambling times”,Phys. Rev. D106[12](2022) 126018,arXiv:2209.00253 [hep-th]

  58. [58]

    Island on codimension- two branes in AdS/dCFT

    P.-J. Hu, D. Li and R.-X. Miao, “Island on codimension- two branes in AdS/dCFT”,JHEP11(2022) 008, arXiv:2208.11982 [hep-th]

  59. [59]

    Entanglement islands in gen- eralized two-dimensional dilaton black holes

    M.-H. Yu and X.-H. Ge, “Entanglement islands in gen- eralized two-dimensional dilaton black holes”,Phys. Rev. D107[6](2023) 066020,arXiv:2208.01943 [hep-th]

  60. [60]

    Page curve for an eternal Schwarzschild black hole in a dimensionally re- duced model of dilaton gravity

    S. Djordjevi´ c, A. Goˇ canin, D. Goˇ canin and V. Radovanovi´ c, “Page curve for an eternal Schwarzschild black hole in a dimensionally re- duced model of dilaton gravity”,Phys. Rev. D106[10] (2022) 105015,arXiv:2207.07409 [hep-th]

  61. [61]

    Page curve and island in EGB gravity

    A. Anand, “Page curve and island in EGB gravity”, Nucl. Phys. B993(2023) 116284,arXiv:2205.13785 [hep-th]

  62. [62]

    Islands in Kerr–de Sitter spacetime and their flat limit

    S. Azarnia and R. Fareghbal, “Islands in Kerr–de Sitter spacetime and their flat limit”,Phys. Rev. D106[2] (2022) 026012,arXiv:2204.08488 [hep-th]

  63. [63]

    Information paradox and island in quasi- de Sitter space

    M.-S. Seo, “Information paradox and island in quasi- de Sitter space”,Eur. Phys. J. C82[12](2022) 1082, arXiv:2204.04585 [hep-th]. 11

  64. [64]

    Page curves for accelerating black holes

    M.-H. Yu, X.-H. Ge and C.-Y. Lu, “Page curves for accelerating black holes”,Eur. Phys. J. C83[12](2023) 1104,arXiv:2306.11407 [hep-th]

  65. [65]

    Islands and Page curves in 4d from Type IIB

    C. F. Uhlemann, “Islands and Page curves in 4d from Type IIB”,JHEP08(2021) 104,arXiv:2105.00008 [hep-th]

  66. [66]

    Islands in Kerr–Newman black holes

    M.-H. Yu and X.-H. Ge, “Islands in Kerr–Newman black holes”,Eur. Phys. J. C86[3](2026) 276, arXiv:2510.24006 [hep-th]

  67. [67]

    Island of an acoustic black hole in Schwarzschild spacetime

    Y.-Y. Cheng and J.-R. Sun, “Island of an acoustic black hole in Schwarzschild spacetime”,Phys. Rev. D113[6] (2026) 064030,arXiv:2512.09460 [hep-th]

  68. [68]

    Page curves and island’s delays in asymptot- ically flat 2d spacetimes with injections

    Y. Saito, “Page curves and island’s delays in asymptot- ically flat 2d spacetimes with injections”,PTEP2026 (2025) 013,arXiv:2509.03997 [hep-th]

  69. [69]

    Entanglement islands and the Page curve of Hawking radiation for rotating Kerr black holes

    L. Wang and R. Li, “Entanglement islands and the Page curve of Hawking radiation for rotating Kerr black holes”,Phys. Rev. D110[6](2024) 066012, arXiv:2406.13949 [hep-th]

  70. [70]

    Geometric constraints via Page curves: insights from island rule and quantum focusing conjecture*

    M.-H. Yu and X.-H. Ge, “Geometric constraints via Page curves: insights from island rule and quantum focusing conjecture*”,Chin. Phys. C49[4](2025) 045107,arXiv:2405.03220 [hep-th]

  71. [71]

    Small Schwarzschild de Sitter black holes, the future boundary and islands

    K. Goswami and K. Narayan, “Small Schwarzschild de Sitter black holes, the future boundary and islands”, JHEP05(2024) 016,arXiv:2312.05904 [hep-th]

  72. [72]

    Probing the Page transition via approxi- mate quantum error correction

    H. Zhong, “Probing the Page transition via approxi- mate quantum error correction”,JHEP01(2025) 086, arXiv:2408.15104 [hep-th]

  73. [73]

    Islands in cosmology

    T. Hartman, Y. Jiang and E. Shaghoulian, “Islands in cosmology”,JHEP11(2020) 111,arXiv:2008.01022 [hep-th]

  74. [74]

    Islands in FRW Cosmologies

    R. Esp´ ındola, B. Najian and D. Nikolakopoulou, “Islands in FRW Cosmologies”,arXiv:2203.04433 [hep-th]

  75. [75]

    Islands in Bianchi type I universe

    I. Ben-Dayan, M. Hadad and A. Srivastava, “Islands in Bianchi type I universe”,Phys. Rev. D111[4](2025) 046015,arXiv:2409.15425 [hep-th]

  76. [76]

    Islands in the fluid: islands are common in cosmology

    I. Ben-Dayan, M. Hadad and E. Wildenhain, “Islands in the fluid: islands are common in cosmology”,JHEP 03(2023) 077,arXiv:2211.16600 [hep-th]

  77. [77]

    Reflected entropy and islands in a braneworld cosmology

    D. Basu, A. Chandra and H. Chourasiya, “Reflected entropy and islands in a braneworld cosmology”,JHEP 02(2026) 032,arXiv:2503.17819 [hep-th]

  78. [78]

    Information para- dox and its resolution in de Sitter holography

    H. Geng, Y. Nomura and H.-Y. Sun, “Information para- dox and its resolution in de Sitter holography”,Phys. Rev. D103[12](2021) 126004,arXiv:2103.07477 [hep-th]

  79. [79]

    Non-extremal island in de Sitter gravity

    P.-X. Hao, T. Kawamoto, S.-M. Ruan and T. Takayanagi, “Non-extremal island in de Sitter gravity”,JHEP03(2025) 004,arXiv:2407.21617 [hep-th]

  80. [80]

    Replica wormholes and entanglement islands in the Karch-Randall braneworld

    H. Geng, “Replica wormholes and entanglement islands in the Karch-Randall braneworld”,JHEP01(2025) 063,arXiv:2405.14872 [hep-th]

Showing first 80 references.