Quasi-optimal quantum Markov chain spectral gap estimation

Fuente: arXiv
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Hauptverfasser: Connolly, Adam, Herbert, Steven, Sorci, Julien
Format: Preprint
Veröffentlicht: 2026
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author Connolly, Adam
Herbert, Steven
Sorci, Julien
author_facet Connolly, Adam
Herbert, Steven
Sorci, Julien
contents This paper proposes a quantum algorithm for Markov chain spectral gap estimation that is quasi-optimal (i.e., optimal up to a polylogarithmic factor) in the number of vertices for all parameters, and additionally quasi-optimal in the reciprocal of the spectral gap itself, if the permitted relative error is above some critical value. In particular, these results constitute an almost quadratic advantage over the best-possible classical algorithm. Our algorithm also improves on the quantum state of the art, and we contend that this is not just theoretically interesting but also potentially practically impactful in real-world applications: knowing a Markov chain's spectral gap can speed-up sampling in Markov chain Monte Carlo. Our approach uses the quantum singular value transformation, and as a result we also develop some theory around block-encoding Markov chain transition matrices, which is potentially of independent interest. In particular, we introduce explicit block-encoding methods for the transition matrices of two algebraically-defined classes of Markov chains.
format Preprint
id arxiv_https___arxiv_org_abs_2601_07601
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quasi-optimal quantum Markov chain spectral gap estimation
Connolly, Adam
Herbert, Steven
Sorci, Julien
Quantum Physics
This paper proposes a quantum algorithm for Markov chain spectral gap estimation that is quasi-optimal (i.e., optimal up to a polylogarithmic factor) in the number of vertices for all parameters, and additionally quasi-optimal in the reciprocal of the spectral gap itself, if the permitted relative error is above some critical value. In particular, these results constitute an almost quadratic advantage over the best-possible classical algorithm. Our algorithm also improves on the quantum state of the art, and we contend that this is not just theoretically interesting but also potentially practically impactful in real-world applications: knowing a Markov chain's spectral gap can speed-up sampling in Markov chain Monte Carlo. Our approach uses the quantum singular value transformation, and as a result we also develop some theory around block-encoding Markov chain transition matrices, which is potentially of independent interest. In particular, we introduce explicit block-encoding methods for the transition matrices of two algebraically-defined classes of Markov chains.
title Quasi-optimal quantum Markov chain spectral gap estimation
topic Quantum Physics
url https://arxiv.org/abs/2601.07601