Learning low-degree quantum objects

Fuente: arXiv
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Main Authors: Arunachalam, Srinivasan, Dutt, Arkopal, Gutiérrez, Francisco Escudero, Palazuelos, Carlos
Format: Preprint
Published: 2024
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author Arunachalam, Srinivasan
Dutt, Arkopal
Gutiérrez, Francisco Escudero
Palazuelos, Carlos
author_facet Arunachalam, Srinivasan
Dutt, Arkopal
Gutiérrez, Francisco Escudero
Palazuelos, Carlos
contents We consider the problem of learning low-degree quantum objects up to $\varepsilon$-error in $\ell_2$-distance. We show the following results: $(i)$ unknown $n$-qubit degree-$d$ (in the Pauli basis) quantum channels and unitaries can be learned using $O(1/\varepsilon^d)$ queries (independent of $n$), $(ii)$ polynomials $p:\{-1,1\}^n\rightarrow [-1,1]$ arising from $d$-query quantum algorithms can be classically learned from $O((1/\varepsilon)^d\cdot \log n)$ many random examples $(x,p(x))$ (which implies learnability even for $d=O(\log n)$), and $(iii)$ degree-$d$ polynomials $p:\{-1,1\}^n\to [-1,1]$ can be learned through $O(1/\varepsilon^d)$ queries to a quantum unitary $U_p$ that block-encodes $p$. Our main technical contributions are new Bohnenblust-Hille inequalities for quantum channels and completely bounded~polynomials.
format Preprint
id arxiv_https___arxiv_org_abs_2405_10933
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Learning low-degree quantum objects
Arunachalam, Srinivasan
Dutt, Arkopal
Gutiérrez, Francisco Escudero
Palazuelos, Carlos
Quantum Physics
Computational Complexity
Data Structures and Algorithms
Machine Learning
Functional Analysis
We consider the problem of learning low-degree quantum objects up to $\varepsilon$-error in $\ell_2$-distance. We show the following results: $(i)$ unknown $n$-qubit degree-$d$ (in the Pauli basis) quantum channels and unitaries can be learned using $O(1/\varepsilon^d)$ queries (independent of $n$), $(ii)$ polynomials $p:\{-1,1\}^n\rightarrow [-1,1]$ arising from $d$-query quantum algorithms can be classically learned from $O((1/\varepsilon)^d\cdot \log n)$ many random examples $(x,p(x))$ (which implies learnability even for $d=O(\log n)$), and $(iii)$ degree-$d$ polynomials $p:\{-1,1\}^n\to [-1,1]$ can be learned through $O(1/\varepsilon^d)$ queries to a quantum unitary $U_p$ that block-encodes $p$. Our main technical contributions are new Bohnenblust-Hille inequalities for quantum channels and completely bounded~polynomials.
title Learning low-degree quantum objects
topic Quantum Physics
Computational Complexity
Data Structures and Algorithms
Machine Learning
Functional Analysis
url https://arxiv.org/abs/2405.10933