A Cautionary Note on Quantum Oracles

Fuente: arXiv
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Main Authors: Agarwal, Avantika, Kundu, Srijita
Format: Preprint
Published: 2025
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author Agarwal, Avantika
Kundu, Srijita
author_facet Agarwal, Avantika
Kundu, Srijita
contents In recent years, the quantum oracle model introduced by Aaronson and Kuperberg (2007) has found a lot of use in showing oracle separations between complexity classes and cryptographic primitives. It is generally assumed that proof techniques that do not relativize with respect to quantum oracles will also not relativize with respect to classical oracles. In this note, we show that this is not the case: specifically, we show that there is a quantum oracle problem that is contained in the class QMA, but not in a class we call polyQCPH. The class polyQCPH is equal to PSPACE with respect to classical oracles, and it is a well-known result that QMA is contained in PSPACE (also with respect to classical oracles). We also show that the same separation holds relative to a distributional oracle, which is a model introduced by Natarajan and Nirkhe (2024). We believe our findings show the need for some caution when using these non-standard oracle models, particularly when showing separations between quantum and classical resources.
format Preprint
id arxiv_https___arxiv_org_abs_2504_19470
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Cautionary Note on Quantum Oracles
Agarwal, Avantika
Kundu, Srijita
Quantum Physics
Computational Complexity
In recent years, the quantum oracle model introduced by Aaronson and Kuperberg (2007) has found a lot of use in showing oracle separations between complexity classes and cryptographic primitives. It is generally assumed that proof techniques that do not relativize with respect to quantum oracles will also not relativize with respect to classical oracles. In this note, we show that this is not the case: specifically, we show that there is a quantum oracle problem that is contained in the class QMA, but not in a class we call polyQCPH. The class polyQCPH is equal to PSPACE with respect to classical oracles, and it is a well-known result that QMA is contained in PSPACE (also with respect to classical oracles). We also show that the same separation holds relative to a distributional oracle, which is a model introduced by Natarajan and Nirkhe (2024). We believe our findings show the need for some caution when using these non-standard oracle models, particularly when showing separations between quantum and classical resources.
title A Cautionary Note on Quantum Oracles
topic Quantum Physics
Computational Complexity
url https://arxiv.org/abs/2504.19470