Probabilistic state synthesis based on optimal convex approximation

Abstract When preparing a pure state with a quantum circuit, there is an unavoidable approximation error due to the compilation error in fault-tolerant implementation. A recently proposed approach called probabilistic state synthesis, where the circuit is probabilistically sampled, is able to reduce...

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Main Authors: Seiseki Akibue, Go Kato, Seiichiro Tani
Format: Article
Language:English
Published: Nature Portfolio 2024-01-01
Series:npj Quantum Information
Online Access:https://doi.org/10.1038/s41534-023-00793-7
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author Seiseki Akibue
Go Kato
Seiichiro Tani
author_facet Seiseki Akibue
Go Kato
Seiichiro Tani
author_sort Seiseki Akibue
collection DOAJ
description Abstract When preparing a pure state with a quantum circuit, there is an unavoidable approximation error due to the compilation error in fault-tolerant implementation. A recently proposed approach called probabilistic state synthesis, where the circuit is probabilistically sampled, is able to reduce the approximation error compared to conventional deterministic synthesis. In this paper, we demonstrate that the optimal probabilistic synthesis quadratically reduces the approximation error. Moreover, we show that a deterministic synthesis algorithm can be efficiently converted into a probabilistic one that achieves this quadratic error reduction. We also numerically demonstrate how this conversion reduces the T-count and analytically prove that this conversion halves an information-theoretic lower bound on the circuit size. In order to derive these results, we prove general theorems about the optimal convex approximation of a quantum state. Furthermore, we demonstrate that this theorem can be used to analyze an entanglement measure.
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spelling doaj.art-617f1e95071a4ddab61f735ed9750f442024-01-07T12:38:14ZengNature Portfolionpj Quantum Information2056-63872024-01-011011910.1038/s41534-023-00793-7Probabilistic state synthesis based on optimal convex approximationSeiseki Akibue0Go Kato1Seiichiro Tani2NTT Communication Science Laboratories, NTT CorporationAdvanced ICT Research Institute, NICTNTT Communication Science Laboratories, NTT CorporationAbstract When preparing a pure state with a quantum circuit, there is an unavoidable approximation error due to the compilation error in fault-tolerant implementation. A recently proposed approach called probabilistic state synthesis, where the circuit is probabilistically sampled, is able to reduce the approximation error compared to conventional deterministic synthesis. In this paper, we demonstrate that the optimal probabilistic synthesis quadratically reduces the approximation error. Moreover, we show that a deterministic synthesis algorithm can be efficiently converted into a probabilistic one that achieves this quadratic error reduction. We also numerically demonstrate how this conversion reduces the T-count and analytically prove that this conversion halves an information-theoretic lower bound on the circuit size. In order to derive these results, we prove general theorems about the optimal convex approximation of a quantum state. Furthermore, we demonstrate that this theorem can be used to analyze an entanglement measure.https://doi.org/10.1038/s41534-023-00793-7
spellingShingle Seiseki Akibue
Go Kato
Seiichiro Tani
Probabilistic state synthesis based on optimal convex approximation
npj Quantum Information
title Probabilistic state synthesis based on optimal convex approximation
title_full Probabilistic state synthesis based on optimal convex approximation
title_fullStr Probabilistic state synthesis based on optimal convex approximation
title_full_unstemmed Probabilistic state synthesis based on optimal convex approximation
title_short Probabilistic state synthesis based on optimal convex approximation
title_sort probabilistic state synthesis based on optimal convex approximation
url https://doi.org/10.1038/s41534-023-00793-7
work_keys_str_mv AT seisekiakibue probabilisticstatesynthesisbasedonoptimalconvexapproximation
AT gokato probabilisticstatesynthesisbasedonoptimalconvexapproximation
AT seiichirotani probabilisticstatesynthesisbasedonoptimalconvexapproximation