Regressions on quantum neural networks at maximal expressivity

Abstract Considering a universal deep neural network organized as a series of nested qubit rotations, accomplished by adjustable data re-uploads we analyze its expressivity. This ability to approximate continuous functions in regression tasks is quantified making use of a partial Fourier decompositi...

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Main Authors: Iván Panadero, Yue Ban, Hilario Espinós, Ricardo Puebla, Jorge Casanova, Erik Torrontegui
Format: Article
Language:English
Published: Nature Portfolio 2024-12-01
Series:Scientific Reports
Subjects:
Online Access:https://doi.org/10.1038/s41598-024-81436-5
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author Iván Panadero
Yue Ban
Hilario Espinós
Ricardo Puebla
Jorge Casanova
Erik Torrontegui
author_facet Iván Panadero
Yue Ban
Hilario Espinós
Ricardo Puebla
Jorge Casanova
Erik Torrontegui
author_sort Iván Panadero
collection DOAJ
description Abstract Considering a universal deep neural network organized as a series of nested qubit rotations, accomplished by adjustable data re-uploads we analyze its expressivity. This ability to approximate continuous functions in regression tasks is quantified making use of a partial Fourier decomposition of the generated output and systematically benchmarked with the aid of a teacher-student scheme. While the maximal expressive power increases with the depth of the network and the number of qubits, it is fundamentally bounded by the data encoding mechanism. However, we show that the measurement of the network generated output drastically modifies the attainability of this bound. Global-entangling measurements on the network can saturate the maximal expressive bound leading to an enhancement of the approximation capabilities of the network compared to local readouts of the individual qubits in non-entangling networks. We attribute this enhancement to a larger survival set of Fourier harmonics when decomposing the output signal.
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spelling doaj-art-95a4d90f93c6401d9a6c0d839801953a2025-01-05T12:24:53ZengNature PortfolioScientific Reports2045-23222024-12-0114111610.1038/s41598-024-81436-5Regressions on quantum neural networks at maximal expressivityIván Panadero0Yue Ban1Hilario Espinós2Ricardo Puebla3Jorge Casanova4Erik Torrontegui5Departamento de Física, Universidad Carlos III de MadridDepartamento de Física, Universidad Carlos III de MadridDepartamento de Física, Universidad Carlos III de MadridDepartamento de Física, Universidad Carlos III de MadridDepartment of Physical Chemistry, University of the Basque Country UPV/EHUDepartamento de Física, Universidad Carlos III de MadridAbstract Considering a universal deep neural network organized as a series of nested qubit rotations, accomplished by adjustable data re-uploads we analyze its expressivity. This ability to approximate continuous functions in regression tasks is quantified making use of a partial Fourier decomposition of the generated output and systematically benchmarked with the aid of a teacher-student scheme. While the maximal expressive power increases with the depth of the network and the number of qubits, it is fundamentally bounded by the data encoding mechanism. However, we show that the measurement of the network generated output drastically modifies the attainability of this bound. Global-entangling measurements on the network can saturate the maximal expressive bound leading to an enhancement of the approximation capabilities of the network compared to local readouts of the individual qubits in non-entangling networks. We attribute this enhancement to a larger survival set of Fourier harmonics when decomposing the output signal.https://doi.org/10.1038/s41598-024-81436-5Quantum neural networksQuantum machine learning
spellingShingle Iván Panadero
Yue Ban
Hilario Espinós
Ricardo Puebla
Jorge Casanova
Erik Torrontegui
Regressions on quantum neural networks at maximal expressivity
Scientific Reports
Quantum neural networks
Quantum machine learning
title Regressions on quantum neural networks at maximal expressivity
title_full Regressions on quantum neural networks at maximal expressivity
title_fullStr Regressions on quantum neural networks at maximal expressivity
title_full_unstemmed Regressions on quantum neural networks at maximal expressivity
title_short Regressions on quantum neural networks at maximal expressivity
title_sort regressions on quantum neural networks at maximal expressivity
topic Quantum neural networks
Quantum machine learning
url https://doi.org/10.1038/s41598-024-81436-5
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