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Unitary operator discrimination is a fundamental problem in quantum information theory. The basic version of this problem can be described as follows: Given a black box implementing a unitary operator U∈S:={U1, U2} under some probability distribution over S, the goal is to decide whether U=U1 or U=U2. In this paper, we consider the query complexity of this problem. We show that there exists a quantum algorithm that solves this problem with bounded error probability using $lceil{sqrt{6} heta_{ m cover}^{-1}} ceil$ queries to the black box in the worst case, i.e., under any probability distribution over S, where the parameter θcover, which is determined by the eigenvalues of $U_1^dagger {U_2}$, represents the “closeness” between U1 and U2. We also show that this upper bound is essentially tight: we prove that for every θcover > 0 there exist operators U1 and U2 such that any quantum algorithm solving this problem with bounded error probability requires at least $lceil{rac{2}{3 heta_{ m cover}}} ceil$ queries under uniform distribution over S.
Akinori KAWACHI
Osaka University
Kenichi KAWANO
Tokushima University
Francois LE GALL
Kyoto University
Suguru TAMAKI
Kyoto University
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Akinori KAWACHI, Kenichi KAWANO, Francois LE GALL, Suguru TAMAKI, "Quantum Query Complexity of Unitary Operator Discrimination" in IEICE TRANSACTIONS on Information,
vol. E102-D, no. 3, pp. 483-491, March 2019, doi: 10.1587/transinf.2018FCP0012.
Abstract: Unitary operator discrimination is a fundamental problem in quantum information theory. The basic version of this problem can be described as follows: Given a black box implementing a unitary operator U∈S:={U1, U2} under some probability distribution over S, the goal is to decide whether U=U1 or U=U2. In this paper, we consider the query complexity of this problem. We show that there exists a quantum algorithm that solves this problem with bounded error probability using $lceil{sqrt{6} heta_{
m cover}^{-1}}
ceil$ queries to the black box in the worst case, i.e., under any probability distribution over S, where the parameter θcover, which is determined by the eigenvalues of $U_1^dagger {U_2}$, represents the “closeness” between U1 and U2. We also show that this upper bound is essentially tight: we prove that for every θcover > 0 there exist operators U1 and U2 such that any quantum algorithm solving this problem with bounded error probability requires at least $lceil{rac{2}{3 heta_{
m cover}}}
ceil$ queries under uniform distribution over S.
URL: https://global.ieice.org/en_transactions/information/10.1587/transinf.2018FCP0012/_p
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@ARTICLE{e102-d_3_483,
author={Akinori KAWACHI, Kenichi KAWANO, Francois LE GALL, Suguru TAMAKI, },
journal={IEICE TRANSACTIONS on Information},
title={Quantum Query Complexity of Unitary Operator Discrimination},
year={2019},
volume={E102-D},
number={3},
pages={483-491},
abstract={Unitary operator discrimination is a fundamental problem in quantum information theory. The basic version of this problem can be described as follows: Given a black box implementing a unitary operator U∈S:={U1, U2} under some probability distribution over S, the goal is to decide whether U=U1 or U=U2. In this paper, we consider the query complexity of this problem. We show that there exists a quantum algorithm that solves this problem with bounded error probability using $lceil{sqrt{6} heta_{
m cover}^{-1}}
ceil$ queries to the black box in the worst case, i.e., under any probability distribution over S, where the parameter θcover, which is determined by the eigenvalues of $U_1^dagger {U_2}$, represents the “closeness” between U1 and U2. We also show that this upper bound is essentially tight: we prove that for every θcover > 0 there exist operators U1 and U2 such that any quantum algorithm solving this problem with bounded error probability requires at least $lceil{rac{2}{3 heta_{
m cover}}}
ceil$ queries under uniform distribution over S.},
keywords={},
doi={10.1587/transinf.2018FCP0012},
ISSN={1745-1361},
month={March},}
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TY - JOUR
TI - Quantum Query Complexity of Unitary Operator Discrimination
T2 - IEICE TRANSACTIONS on Information
SP - 483
EP - 491
AU - Akinori KAWACHI
AU - Kenichi KAWANO
AU - Francois LE GALL
AU - Suguru TAMAKI
PY - 2019
DO - 10.1587/transinf.2018FCP0012
JO - IEICE TRANSACTIONS on Information
SN - 1745-1361
VL - E102-D
IS - 3
JA - IEICE TRANSACTIONS on Information
Y1 - March 2019
AB - Unitary operator discrimination is a fundamental problem in quantum information theory. The basic version of this problem can be described as follows: Given a black box implementing a unitary operator U∈S:={U1, U2} under some probability distribution over S, the goal is to decide whether U=U1 or U=U2. In this paper, we consider the query complexity of this problem. We show that there exists a quantum algorithm that solves this problem with bounded error probability using $lceil{sqrt{6} heta_{
m cover}^{-1}}
ceil$ queries to the black box in the worst case, i.e., under any probability distribution over S, where the parameter θcover, which is determined by the eigenvalues of $U_1^dagger {U_2}$, represents the “closeness” between U1 and U2. We also show that this upper bound is essentially tight: we prove that for every θcover > 0 there exist operators U1 and U2 such that any quantum algorithm solving this problem with bounded error probability requires at least $lceil{rac{2}{3 heta_{
m cover}}}
ceil$ queries under uniform distribution over S.
ER -