From Promises to Totality: A Framework for Ruling Out Quantum Speedups

Fuente: arXiv
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Hauptverfasser: Huffstutler, Thomas, Kapshikar, Upendra, Miloschewsky, David, Podder, Supartha
Format: Preprint
Veröffentlicht: 2026
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author Huffstutler, Thomas
Kapshikar, Upendra
Miloschewsky, David
Podder, Supartha
author_facet Huffstutler, Thomas
Kapshikar, Upendra
Miloschewsky, David
Podder, Supartha
contents We study when partial Boolean functions can (and cannot) exhibit superpolynomial quantum query speedups, and develop a general framework for ruling out such speedups via two complementary lenses: promise-aware complexity measures and function completions. First, we introduce promise versions of standard combinatorial measures (including block sensitivity and related variants) and prove that if the relevant promise and completion measures collapse, then deterministic and quantum query complexities are necessarily polynomially related, i.e., $D(f)=poly(Q(f))$. We then analyze structured families of promises, including symmetric partial functions and promises supported on Hamming slices, obtaining sharp (up to polynomial factors) characterizations in terms of a single gap parameter for the symmetric case and refined slice-dependent bounds for $k$-slice domains. Next, we formalize completion complexity as the minimum of a measure over total completions of a partial function, and show that completability of a measure captures the possibility of superpolynomial quantum speedups. Finally, we apply this viewpoint to derive broad non-speedup criteria for some classes of functions admitting well-behaved completions, such as functions with low maximum influence on both the standard and $p$-biased hypercubes and functions with efficiently identifiable domains, and then show some hardness results for general completion techniques.
format Preprint
id arxiv_https___arxiv_org_abs_2603_29256
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle From Promises to Totality: A Framework for Ruling Out Quantum Speedups
Huffstutler, Thomas
Kapshikar, Upendra
Miloschewsky, David
Podder, Supartha
Quantum Physics
We study when partial Boolean functions can (and cannot) exhibit superpolynomial quantum query speedups, and develop a general framework for ruling out such speedups via two complementary lenses: promise-aware complexity measures and function completions. First, we introduce promise versions of standard combinatorial measures (including block sensitivity and related variants) and prove that if the relevant promise and completion measures collapse, then deterministic and quantum query complexities are necessarily polynomially related, i.e., $D(f)=poly(Q(f))$. We then analyze structured families of promises, including symmetric partial functions and promises supported on Hamming slices, obtaining sharp (up to polynomial factors) characterizations in terms of a single gap parameter for the symmetric case and refined slice-dependent bounds for $k$-slice domains. Next, we formalize completion complexity as the minimum of a measure over total completions of a partial function, and show that completability of a measure captures the possibility of superpolynomial quantum speedups. Finally, we apply this viewpoint to derive broad non-speedup criteria for some classes of functions admitting well-behaved completions, such as functions with low maximum influence on both the standard and $p$-biased hypercubes and functions with efficiently identifiable domains, and then show some hardness results for general completion techniques.
title From Promises to Totality: A Framework for Ruling Out Quantum Speedups
topic Quantum Physics
url https://arxiv.org/abs/2603.29256