Unconditional proofs of quantumness between small-space machines

Fuente: arXiv
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Main Authors: Say, A. C. Cem, Gezer, M. Utkan
Format: Preprint
Published: 2024
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author Say, A. C. Cem
Gezer, M. Utkan
author_facet Say, A. C. Cem
Gezer, M. Utkan
contents A proof of quantumness is a protocol through which a classical machine can test whether a purportedly quantum device, with comparable time and memory resources, is performing a computation that is impossible for classical computers. Existing approaches to provide proofs of quantumness depend on unproven assumptions about some task being impossible for machines of a particular model under certain resource restrictions. We study a setup where both devices have space bounds $\mathit{o}(\log \log n)$. Under such memory budgets, it has been unconditionally proven that probabilistic Turing machines are unable to solve certain computational problems. We formulate a new class of problems, and show that these problems are polynomial-time solvable for quantum machines, impossible for classical machines, and have the property that their solutions can be "proved" by a small-space quantum machine to a classical machine with the same space bound. These problems form the basis of our newly defined protocol, where the polynomial-time verifier's verdict about the tested machine's quantumness is not conditional on an unproven weakness assumption.
format Preprint
id arxiv_https___arxiv_org_abs_2412_02662
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unconditional proofs of quantumness between small-space machines
Say, A. C. Cem
Gezer, M. Utkan
Computational Complexity
Formal Languages and Automata Theory
Quantum Physics
A proof of quantumness is a protocol through which a classical machine can test whether a purportedly quantum device, with comparable time and memory resources, is performing a computation that is impossible for classical computers. Existing approaches to provide proofs of quantumness depend on unproven assumptions about some task being impossible for machines of a particular model under certain resource restrictions. We study a setup where both devices have space bounds $\mathit{o}(\log \log n)$. Under such memory budgets, it has been unconditionally proven that probabilistic Turing machines are unable to solve certain computational problems. We formulate a new class of problems, and show that these problems are polynomial-time solvable for quantum machines, impossible for classical machines, and have the property that their solutions can be "proved" by a small-space quantum machine to a classical machine with the same space bound. These problems form the basis of our newly defined protocol, where the polynomial-time verifier's verdict about the tested machine's quantumness is not conditional on an unproven weakness assumption.
title Unconditional proofs of quantumness between small-space machines
topic Computational Complexity
Formal Languages and Automata Theory
Quantum Physics
url https://arxiv.org/abs/2412.02662