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Semiclassical Wormholes toward Typical Entangled States

Javier M. Magán1, Martin Sasieta2, and Brian Swingle2

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Phys. Rev. Lett. 135, 161601 – Published 15 October, 2025

DOI: https://doi.org/10.1103/btw6-44ry

Abstract

What do the typical entangled states of two black holes look like? Do they contain semiclassical interiors? We approach these questions constructively, providing ensembles of states that densely explore the black hole Hilbert space. The states contain very long Einstein-Rosen caterpillars: semiclassical wormholes with large numbers of matter inhomogeneities. Distinguishing these ensembles from the typical entangled states of the black holes is hard. We quantify this by deriving the correspondence between a microscopic notion of quantum randomness and the geometric length of the wormhole. This formalizes a “complexity = geometry” relation.

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Phys. Rev. Lett. 135, 161601– Published 15 October, 2025
  • Received 22 April 2025
  • Accepted 17 September 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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