About

Netta Engelhardt is an Associate Professor of Physics at MIT, with research focusing on understanding the predictions and fundamental structure of quantum gravity via holography and the black hole information paradox. Her work primarily involves quantum gravity within the framework of the AdS/CFT correspondence, exploring the dynamics of black holes in quantum gravity and leveraging insights from the interplay between gravity and quantum information. Her primary research interests include the black hole information paradox, the thermodynamic behavior of black holes, and the cosmic censorship hypothesis, which conjectures that singularities are always hidden behind event horizons. Born in Jerusalem, Israel, and raised in Boston, MA, Engelhardt earned her BSc in physics and mathematics from Brandeis University and her PhD in physics from the University of California, Santa Barbara. She was a postdoctoral fellow at Princeton University and a member of the Princeton Gravity Initiative before joining MIT's faculty in July 2019. Her contributions to the field have been recognized with numerous awards, including the DOE Presidential Early Career Award for Scientists and Engineers in 2025, the Gribov Medal in 2023, and the Breakthrough Prize in 2021 for her work on the quantum information content of black holes and their radiation.

Research topics

• Physics
• Theoretical physics
• Quantum mechanics
• Statistical physics
• Computer Science
• Algorithm
• Optics
• Mathematics
• Classical mechanics
• Combinatorics

Selected publications

• Spoofing entanglement in holography

  Journal of High Energy Physics · 2026-05-11 · 1 citations

  preprintOpen access1st author

  A bstract A defining property of Hawking radiation is that states with very low entanglement masquerade as highly mixed states; this property is captured by a quantum computational phenomenon known as spoofing entanglement. Motivated by the potential implications for black hole information and the emergence of spacetime connectivity, as well as possible applications of spoofing entanglement, we investigate the geometrization of two types of entanglement spoofers in AdS/CFT: so-called EFI pairs and pseudoentangled state ensembles. We show that (a strengthened version of) EFI pairs with a semiclassical bulk dual have a Python’s Lunch; the maximally mixed state over the pseudoentangled state ensemble likewise features a Python’s Lunch. Since a Python’s Lunch must lie behind an event horizon, we find that black holes are the exclusive gravitational source of entanglement spoofing in the semiclassical limit. Finally, we use an extant construction of holographic pseudorandom states to yield a candidate example of a pseudoentangled state ensemble with a semiclassical bulk dual.

  PublisherOA PDFDOI

• A Quantum Singularity Theorem for the Evaporating Black Hole

  ArXiv.org · 2026-05-06

  articleOpen access1st authorCorresponding

  We prove a singularity theorem in semiclassical gravity without assuming global hyperbolicity or the null energy/curvature condition; the former is replaced by the weaker causality conditions of stable causality and past reflectivity, and the latter is replaced as is standard by the Generalized Second Law. This establishes in particular that the standard models of evaporating black holes are singular - i.e. they are null geodesically incomplete.

  PublisherOA PDF

• A Semiclassical Diagnostic for Spacetime Emergence

  ArXiv.org · 2026-05-07

  articleOpen access1st authorCorresponding

  Recent developments have shown that some semiclassical spacetimes cannot emerge from a traditional application of the rules of holography, prompting proposals for restoring their emergence with "observer rules". In this paper, we propose a general semiclassical diagnostic of such failures of emergence, and of the extent to which observer rules can fix them. Our diagnostic is the presence of certain "evanescent" quantum extremal surfaces, which are distinguished by an upper bound on their area rather than their generalized entropy. In particular, the generalized entropy of an evanescent QES may be large: even though its area term must be small, its bulk entanglement term is unconstrained. This feature is explained by an operational distinction between classical and quantum connectivity in semiclassical gravity, or equivalently between the two summands of the generalized entropy.

  PublisherOA PDF

• A Semiclassical Diagnostic for Spacetime Emergence

  arXiv (Cornell University) · 2026-05-07

  preprintOpen access1st authorCorresponding

  Recent developments have shown that some semiclassical spacetimes cannot emerge from a traditional application of the rules of holography, prompting proposals for restoring their emergence with "observer rules". In this paper, we propose a general semiclassical diagnostic of such failures of emergence, and of the extent to which observer rules can fix them. Our diagnostic is the presence of certain "evanescent" quantum extremal surfaces, which are distinguished by an upper bound on their area rather than their generalized entropy. In particular, the generalized entropy of an evanescent QES may be large: even though its area term must be small, its bulk entanglement term is unconstrained. This feature is explained by an operational distinction between classical and quantum connectivity in semiclassical gravity, or equivalently between the two summands of the generalized entropy.

  PublisherDOI

• A Quantum Singularity Theorem for the Evaporating Black Hole

  arXiv (Cornell University) · 2026-05-06

  preprintOpen access1st authorCorresponding

  We prove a singularity theorem in semiclassical gravity without assuming global hyperbolicity or the null energy/curvature condition; the former is replaced by the weaker causality conditions of stable causality and past reflectivity, and the latter is replaced as is standard by the Generalized Second Law. This establishes in particular that the standard models of evaporating black holes are singular - i.e. they are null geodesically incomplete.

  PublisherDOI

• Cryptographic Censorship

  Journal of High Energy Physics · 2025-01-23 · 11 citations

  articleOpen access1st authorCorresponding

  A bstract We formulate and take two large strides towards proving a quantum version of the weak cosmic censorship conjecture. We first prove “Cryptographic Censorship”: a theorem showing that when the time evolution operator of a holographic CFT is approximately pseudorandom (or Haar random) on some code subspace, then there must be an event horizon in the corresponding bulk dual. This result provides a general condition that guarantees (in finite time) event horizon formation, with minimal assumptions about the global spacetime structure. Our theorem relies on an extension of a recent quantum learning no-go theorem and is proved using new techniques of pseudorandom measure concentration. To apply this result to cosmic censorship, we separate singularities into classical, semi-Planckian, and Planckian types. We illustrate that classical and semi-Planckian singularities are compatible with approximately pseudorandom CFT time evolution; thus, if such singularities are indeed approximately pseudorandom, by Cryptographic Censorship, they cannot exist in the absence of event horizons. This result provides a sufficient condition guaranteeing that seminal holographic results on quantum chaos and thermalization, whose general applicability relies on typicality of horizons, will not be invalidated by the formation of naked singularities in AdS/CFT.

  PublisherOA PDFDOI

• The complexity of learning (pseudo)random dynamics of black holes and other chaotic systems

  Journal of High Energy Physics · 2025-03-20 · 1 citations

  articleOpen accessSenior author

  A bstract It has been recently proposed that the naive semiclassical prediction of non-unitary black hole evaporation can be understood in the fundamental description of the black hole as a consequence of ignorance of high-complexity information. Validity of this conjecture implies that any algorithm which is polynomially bounded in computational complexity cannot accurately reconstruct the black hole dynamics. In this work, we prove that such bounded quantum algorithms cannot accurately predict (pseudo)random unitary dynamics, even if they are given access to an arbitrary set of polynomially complex observables under this time evolution; this shows that “learning” a (pseudo)random unitary is computationally hard. We use the common simplification of modeling black holes and more generally chaotic systems via (pseudo)random dynamics. The quantum algorithms that we consider are completely general, and their attempted guess for the time evolution of black holes is likewise unconstrained: it need not be a linear operator, and may be as general as an arbitrary (e.g. decohering) quantum channel.

  PublisherOA PDFDOI

• Observer complementarity for black holes and holography

  ArXiv.org · 2025-07-08

  preprintOpen access1st authorCorresponding

  We present a mathematical formulation of black hole complementarity based on recent rules for including the observer in quantum cosmology. We argue that this provides a self-consistent treatment of the interior of an evaporating black hole throughout its history, as well as the Antonini-Sasieta-Swingle-Rath configuration where a closed universe is entangled with a pair of AdS universes.

  PublisherOA PDFDOI

• The Making of von Neumann Algebras from Bulk Focusing

  ArXiv.org · 2025-09-05

  preprintOpen access1st authorCorresponding

  The single-trace, infinite-N algebra of an arbitrary region may or may not be a von Neumann algebra depending on the GNS sector. In this paper we identify the holographic dual of this mechanism as a consequence of the focusing of null geodesics; more precisely, this GNS sector-dependence corresponds to the well-known difference between null congruences fired from the bulk and those fired from the boundary. As part of establishing this property, we give a rigorous formulation and proof of causal wedge reconstruction for those general boundary subregions whose single trace algebras support von Neumann algebras at large-N. We discuss a possible finite-N extension and interpretation of our results as an explanation for the Hawking area theorem.

  PublisherOA PDFDOI

• The black hole interior from non-isometric codes and complexity

  Journal of High Energy Physics · 2024-06-24 · 66 citations

  articleOpen access

  A bstract Quantum error correction has given us a natural language for the emergence of spacetime, but the black hole interior poses a challenge for this framework: at late times the apparent number of interior degrees of freedom in effective field theory can vastly exceed the true number of fundamental degrees of freedom, so there can be no isometric (i.e. inner-product preserving) encoding of the former into the latter. In this paper we explain how quantum error correction nonetheless can be used to explain the emergence of the black hole interior, via the idea of “non-isometric codes protected by computational complexity”. We show that many previous ideas, such as the existence of a large number of “null states”, a breakdown of effective field theory for operations of exponential complexity, the quantum extremal surface calculation of the Page curve, post-selection, “state-dependent/state-specific” operator reconstruction, and the “simple entropy” approach to complexity coarse-graining, all fit naturally into this framework, and we illustrate all of these phenomena simultaneously in a soluble model.

  PublisherOA PDFDOI

Recent grants

• Cosmic Censorship from Gauge/Gravity Duality

  NSF · $240k · 2020–2023

Frequent coauthors

• Geoff Penington

  University of California, Berkeley

  15 shared

• Gary T. Horowitz

  12 shared

• Raphael Bousso

  10 shared

• Sebastian Fischetti

  McGill University

  10 shared

• Chris Akers

  6 shared

• Åsmund Folkestad

  6 shared

• Arvin Shahbazi-Moghaddam

  Stanford University

  6 shared

• Aron C. Wall

  University of Cambridge

  5 shared

Awards & honors

• DOE Presidential Early Career Award for Scientists and Engin…
• Gribov Medal (EPS-HEPP) (2023)
• Sloan Research Fellowship (2022)
• DOE Office of Science Early Career Research Program Award (2…
• New Horizons in Physics Prize for Early-Career Achievements…