Elfs, transducers and quantum walks

Fuente: arXiv
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Main Authors: Apers, Simon, Roland, Jérémie, Zhang, Yuxin
Format: Preprint
Published: 2026
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author Apers, Simon
Roland, Jérémie
Zhang, Yuxin
author_facet Apers, Simon
Roland, Jérémie
Zhang, Yuxin
contents Electric flow sampling (elfs) is a new tool in the quantum walk toolbox and a useful primitive for solving search, sampling and optimization problems on graphs. We refine this tool by showing that there exists a zero-error transducer for implementing elfs. More broadly, we establish a zero-error transducer for reflecting about the intersection of two subspaces, yielding an errorfree transducer version of the effective gap lemma. Building on this result, we obtain improved quantum walk algorithms for estimating effective resistances and span program witness sizes with an optimal error scaling, and for sampling from the random walk arrival distribution, via the composition of many elfs. Using this last algorithm, we obtain an up-to-quadratic quantum speedup for semi-supervised learning on expander graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2605_30013
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Elfs, transducers and quantum walks
Apers, Simon
Roland, Jérémie
Zhang, Yuxin
Quantum Physics
Computational Complexity
Data Structures and Algorithms
Electric flow sampling (elfs) is a new tool in the quantum walk toolbox and a useful primitive for solving search, sampling and optimization problems on graphs. We refine this tool by showing that there exists a zero-error transducer for implementing elfs. More broadly, we establish a zero-error transducer for reflecting about the intersection of two subspaces, yielding an errorfree transducer version of the effective gap lemma. Building on this result, we obtain improved quantum walk algorithms for estimating effective resistances and span program witness sizes with an optimal error scaling, and for sampling from the random walk arrival distribution, via the composition of many elfs. Using this last algorithm, we obtain an up-to-quadratic quantum speedup for semi-supervised learning on expander graphs.
title Elfs, transducers and quantum walks
topic Quantum Physics
Computational Complexity
Data Structures and Algorithms
url https://arxiv.org/abs/2605.30013