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Constraints on physical computers in holographic spacetimes

by Aleksander M. Kubicki, Alex May, David Pérez-Garcia

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Submission summary

Authors (as registered SciPost users): Alex May
Submission information
Preprint Link:  (pdf)
Date accepted: 2024-01-02
Date submitted: 2023-12-07 03:01
Submitted by: May, Alex
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • High-Energy Physics - Theory
  • Quantum Physics
Approach: Theoretical


Within the setting of the AdS/CFT correspondence, we ask about the power of computers in the presence of gravity. We show that there are computations on $n$ qubits which cannot be implemented inside of black holes with entropy less than $O(2^n)$. To establish our claim, we argue computations happening inside the black hole must be implementable in a programmable quantum processor, so long as the inputs and description of the unitary to be run are not too large. We then prove a bound on quantum processors which shows many unitaries cannot be implemented inside the black hole, and further show some of these have short descriptions and act on small systems. These unitaries with short descriptions must be computationally forbidden from happening inside the black hole.

Published as SciPost Phys. 16, 024 (2024)

Reports on this Submission

Anonymous Report 1 on 2023-12-14 (Invited Report)


The authors have addressed my concerns in a satisfactory way. I continue to find it puzzling exactly how to interpret these results, but the authors have provided a good discussion of this point.

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