Universal approximation of continuous functions with minimal quantum circuits

Fuente: arXiv
Gespeichert in:
Bibliographische Detailangaben
Hauptverfasser: Pérez-Salinas, Adrián, Rad, Mahtab Yaghubi, Barthe, Alice, Dunjko, Vedran
Format: Preprint
Veröffentlicht: 2024
Schlagworte:
Online-Zugang:
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
_version_ 1866918243611967488
author Pérez-Salinas, Adrián
Rad, Mahtab Yaghubi
Barthe, Alice
Dunjko, Vedran
author_facet Pérez-Salinas, Adrián
Rad, Mahtab Yaghubi
Barthe, Alice
Dunjko, Vedran
contents The conventional paradigm of quantum computing is discrete: it utilizes discrete sets of gates to realize bitstring-to-bitstring mappings, some of them arguably intractable for classical computers. In parameterized quantum approaches, the input becomes continuous and the output represents real-valued functions. While the universality of discrete quantum computers is well understood, basic questions remained open in the continuous case. We focus on universality on multivariate functions. Current approaches require either a number of qubits scaling linearly with the dimension of the input for fixed encodings, or a tunable encoding procedure in single-qubit circuits. The question of whether universality can be reached with a fixed encoding and sub-linearly many qubits remained open for the last five years. In this paper, we answer this question in the affirmative for arbitrary multivariate functions. We provide two methods: (i) a single-qubit circuit where each coordinate of the arguments to the function to represent is input independently, and (ii) a multi-qubit approach where all coordinates are input in one step, with number of qubits scaling logarithmically with the dimension of the argument of the function of interest. We view the first result of inherent and fundamental interest, whereas the second result opens the path towards representing functions whose arguments are densely encoded in a unitary operation, possibly encoding for instance quantum processes.
format Preprint
id arxiv_https___arxiv_org_abs_2411_19152
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Universal approximation of continuous functions with minimal quantum circuits
Pérez-Salinas, Adrián
Rad, Mahtab Yaghubi
Barthe, Alice
Dunjko, Vedran
Quantum Physics
The conventional paradigm of quantum computing is discrete: it utilizes discrete sets of gates to realize bitstring-to-bitstring mappings, some of them arguably intractable for classical computers. In parameterized quantum approaches, the input becomes continuous and the output represents real-valued functions. While the universality of discrete quantum computers is well understood, basic questions remained open in the continuous case. We focus on universality on multivariate functions. Current approaches require either a number of qubits scaling linearly with the dimension of the input for fixed encodings, or a tunable encoding procedure in single-qubit circuits. The question of whether universality can be reached with a fixed encoding and sub-linearly many qubits remained open for the last five years. In this paper, we answer this question in the affirmative for arbitrary multivariate functions. We provide two methods: (i) a single-qubit circuit where each coordinate of the arguments to the function to represent is input independently, and (ii) a multi-qubit approach where all coordinates are input in one step, with number of qubits scaling logarithmically with the dimension of the argument of the function of interest. We view the first result of inherent and fundamental interest, whereas the second result opens the path towards representing functions whose arguments are densely encoded in a unitary operation, possibly encoding for instance quantum processes.
title Universal approximation of continuous functions with minimal quantum circuits
topic Quantum Physics
url https://arxiv.org/abs/2411.19152