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Main Authors: Akil, Ali, Giannelli, Lorenzo, Modesto, Leonardo, Dahlsten, Oscar, Chiribella, Giulio, Brukner, Caslav
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.17031
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author Akil, Ali
Giannelli, Lorenzo
Modesto, Leonardo
Dahlsten, Oscar
Chiribella, Giulio
Brukner, Caslav
author_facet Akil, Ali
Giannelli, Lorenzo
Modesto, Leonardo
Dahlsten, Oscar
Chiribella, Giulio
Brukner, Caslav
contents Black hole evaporation is one of the most striking phenomena at the interface between gravity and quantum physics. In Hawking's semi-classical treatment, where matter is quantum mechanical and the spacetime is definite and classical, evaporation leads to an apparent loss of unitarity of the overall evolution, and to the so-called black hole information paradox. Here, we go beyond this semi-classical treatment and formulate a toy quantum model of black hole evaporation that allows the black hole to evolve into a superposition of being fully evaporated and not fully evaporated, consistent with the Hawking particles being in a coherent superposition of different energy levels. We model Hawking particle production by the repeated action of quantum-controlled unitaries, generating emission from the quantum black hole and accounting for a quantum coherent back-reaction on the black hole matter state. We show that the probability of full annihilation of the black hole matter increases with time until the black hole is, asymptotically, fully evaporated in every branch of the quantum superposition. We prove that under natural assumptions, this evaporation model is unitary, such that the initial state can in principle be recovered from the final asymptotic state of the radiation.
format Preprint
id arxiv_https___arxiv_org_abs_2507_17031
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Quantum Superposition of Black Hole Evaporation Histories: Recovering Unitarity
Akil, Ali
Giannelli, Lorenzo
Modesto, Leonardo
Dahlsten, Oscar
Chiribella, Giulio
Brukner, Caslav
General Relativity and Quantum Cosmology
High Energy Physics - Theory
Quantum Physics
Black hole evaporation is one of the most striking phenomena at the interface between gravity and quantum physics. In Hawking's semi-classical treatment, where matter is quantum mechanical and the spacetime is definite and classical, evaporation leads to an apparent loss of unitarity of the overall evolution, and to the so-called black hole information paradox. Here, we go beyond this semi-classical treatment and formulate a toy quantum model of black hole evaporation that allows the black hole to evolve into a superposition of being fully evaporated and not fully evaporated, consistent with the Hawking particles being in a coherent superposition of different energy levels. We model Hawking particle production by the repeated action of quantum-controlled unitaries, generating emission from the quantum black hole and accounting for a quantum coherent back-reaction on the black hole matter state. We show that the probability of full annihilation of the black hole matter increases with time until the black hole is, asymptotically, fully evaporated in every branch of the quantum superposition. We prove that under natural assumptions, this evaporation model is unitary, such that the initial state can in principle be recovered from the final asymptotic state of the radiation.
title A Quantum Superposition of Black Hole Evaporation Histories: Recovering Unitarity
topic General Relativity and Quantum Cosmology
High Energy Physics - Theory
Quantum Physics
url https://arxiv.org/abs/2507.17031