Complexity and the Hilbert space dimension of 3D gravity

Fuente: arXiv
Salvato in:
Dettagli Bibliografici
Autori principali: Balasubramanian, Vijay, Das, Rathindra Nath, Erdmenger, Johanna, Karl, Jonathan, Verlinde, Herman
Natura: Preprint
Pubblicazione: 2026
Soggetti:
Accesso online:
Tags: Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
_version_ 1866911417663225856
author Balasubramanian, Vijay
Das, Rathindra Nath
Erdmenger, Johanna
Karl, Jonathan
Verlinde, Herman
author_facet Balasubramanian, Vijay
Das, Rathindra Nath
Erdmenger, Johanna
Karl, Jonathan
Verlinde, Herman
contents A central problem in formulating a theory of quantum gravity is to determine the size and structure of the Hilbert space of black holes. Here we use a quantum dynamical Krylov complexity approach to calculate the Hilbert space dimension of a black hole in 2+1-dimensional Anti-de Sitter space. We achieve this by obtaining the spread of an initial thermofield double state over the Krylov basis. The associated Lanczos coefficients match those for chaotic motion on the $SL(2,\mathbb{R})$ group. By including non-perturbative effects in the path integral, which computes coarse-grained ensemble averages, we find that the complexity saturates at late times. The saturation value is given by the exponential of the Bekenstein-Hawking entropy. Our results introduce a new way to compute the Hilbert space dimension of complex interacting systems from the saturating value of spread complexity.
format Preprint
id arxiv_https___arxiv_org_abs_2602_02645
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Complexity and the Hilbert space dimension of 3D gravity
Balasubramanian, Vijay
Das, Rathindra Nath
Erdmenger, Johanna
Karl, Jonathan
Verlinde, Herman
High Energy Physics - Theory
General Relativity and Quantum Cosmology
Mathematical Physics
Quantum Physics
A central problem in formulating a theory of quantum gravity is to determine the size and structure of the Hilbert space of black holes. Here we use a quantum dynamical Krylov complexity approach to calculate the Hilbert space dimension of a black hole in 2+1-dimensional Anti-de Sitter space. We achieve this by obtaining the spread of an initial thermofield double state over the Krylov basis. The associated Lanczos coefficients match those for chaotic motion on the $SL(2,\mathbb{R})$ group. By including non-perturbative effects in the path integral, which computes coarse-grained ensemble averages, we find that the complexity saturates at late times. The saturation value is given by the exponential of the Bekenstein-Hawking entropy. Our results introduce a new way to compute the Hilbert space dimension of complex interacting systems from the saturating value of spread complexity.
title Complexity and the Hilbert space dimension of 3D gravity
topic High Energy Physics - Theory
General Relativity and Quantum Cosmology
Mathematical Physics
Quantum Physics
url https://arxiv.org/abs/2602.02645