Qubit encoding for a mixture of localized functions

Fuente: arXiv
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Autores principales: Kosugi, Taichi, Daimon, Shunsuke, Nishi, Hirofumi, Tsuneyuki, Shinji, Matsushita, Yu-ichiro
Formato: Preprint
Publicado: 2024
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author Kosugi, Taichi
Daimon, Shunsuke
Nishi, Hirofumi
Tsuneyuki, Shinji
Matsushita, Yu-ichiro
author_facet Kosugi, Taichi
Daimon, Shunsuke
Nishi, Hirofumi
Tsuneyuki, Shinji
Matsushita, Yu-ichiro
contents One of the crucial generic techniques for quantum computation is amplitude encoding. Although several approaches have been proposed, each of them often requires exponential classical-computational cost or an oracle whose explicit construction is not provided. Given the growing demands for practical quantum computation, we develop moderately specialized encoding techniques that generate an arbitrary linear combination of localized complex functions. We demonstrate that $n_{\mathrm{loc}}$ discrete Lorentzian functions as an expansion basis set lead to eficient probabilistic encoding, whose computational time is $\mathcal{O}( \max ( n_{\mathrm{loc}}^2 \log n_{\mathrm{loc}},n_{\mathrm{loc}}^2 \log n_q, n_q ))$ for $n_q$ data qubits equipped with $\log_2 n_{\mathrm{loc}}$ ancillae. Furthermore, amplitude amplification in combination with amplitude reduction renders it deterministic analytically with controllable errors and the computational time is reduced to $\mathcal{O}( \max ( n_{\mathrm{loc}}^{3/2} \log n_{\mathrm{loc}}, n_{\mathrm{loc}}^{3/2} \log n_q, n_q )).$ We estimate required resources for applying our scheme to quantum chemistry in real space. We also show the results on real superconducting quantum computers to confirm the validity of our techniques.
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id arxiv_https___arxiv_org_abs_2404_18529
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Qubit encoding for a mixture of localized functions
Kosugi, Taichi
Daimon, Shunsuke
Nishi, Hirofumi
Tsuneyuki, Shinji
Matsushita, Yu-ichiro
Quantum Physics
Strongly Correlated Electrons
One of the crucial generic techniques for quantum computation is amplitude encoding. Although several approaches have been proposed, each of them often requires exponential classical-computational cost or an oracle whose explicit construction is not provided. Given the growing demands for practical quantum computation, we develop moderately specialized encoding techniques that generate an arbitrary linear combination of localized complex functions. We demonstrate that $n_{\mathrm{loc}}$ discrete Lorentzian functions as an expansion basis set lead to eficient probabilistic encoding, whose computational time is $\mathcal{O}( \max ( n_{\mathrm{loc}}^2 \log n_{\mathrm{loc}},n_{\mathrm{loc}}^2 \log n_q, n_q ))$ for $n_q$ data qubits equipped with $\log_2 n_{\mathrm{loc}}$ ancillae. Furthermore, amplitude amplification in combination with amplitude reduction renders it deterministic analytically with controllable errors and the computational time is reduced to $\mathcal{O}( \max ( n_{\mathrm{loc}}^{3/2} \log n_{\mathrm{loc}}, n_{\mathrm{loc}}^{3/2} \log n_q, n_q )).$ We estimate required resources for applying our scheme to quantum chemistry in real space. We also show the results on real superconducting quantum computers to confirm the validity of our techniques.
title Qubit encoding for a mixture of localized functions
topic Quantum Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2404.18529