A divide-and-conquer algorithm for quantum state preparation

Advantages in several fields of research and industry are expected with the rise of quantum computers. However, the computational cost to load classical data in quantum computers can impose restrictions on possible quantum speedups. Known algorithms to create arbitrary quantum states require quantum...

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Bibliographic Details
Published in:Scientific reports Vol. 11; no. 1; pp. 6329 - 12
Main Authors: Araujo, Israel F., Park, Daniel K., Petruccione, Francesco, da Silva, Adenilton J.
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 18.03.2021
Nature Publishing Group
Nature Portfolio
Subjects:
639/705/117
639/705/258
639/766/483/2802
639/766/483/481
Algorithms
Computer applications
Computers
Humanities and Social Sciences
Learning algorithms
Machine learning
multidisciplinary
Quantum computing
Science
Science (multidisciplinary)
ISSN:2045-2322, 2045-2322
Online Access:Get full text
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Summary:Advantages in several fields of research and industry are expected with the rise of quantum computers. However, the computational cost to load classical data in quantum computers can impose restrictions on possible quantum speedups. Known algorithms to create arbitrary quantum states require quantum circuits with depth O ( N ) to load an N -dimensional vector. Here, we show that it is possible to load an N -dimensional vector with exponential time advantage using a quantum circuit with polylogarithmic depth and entangled information in ancillary qubits. Results show that we can efficiently load data in quantum devices using a divide-and-conquer strategy to exchange computational time for space. We demonstrate a proof of concept on a real quantum device and present two applications for quantum machine learning. We expect that this new loading strategy allows the quantum speedup of tasks that require to load a significant volume of information to quantum devices.
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ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-021-85474-1