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A square-root speedup for finding the smallest eigenvalue

delete2024-08-12
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OA
AI
V
Vlad Gheorghiu
M
Michele Mosca
T
Thomas Guilbaud
F
Fabio Fracas
L
Luca Dellantonio *
DOI:10.1088/2058-9565/ad6a36delete
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Abstract

Abstract

En 中文
We describe a quantum algorithm for finding the smallest eigenvalue of a Hermitian matrix. This algorithm combines quantum phase estimation and quantum amplitude estimation to achieve a quadratic speedup with respect to the best classical algorithm in terms of matrix dimensionality, i.e. (O)over tilde(N/epsilon)( 9) black-box queries to an oracle encoding the matrix, where N is the matrix dimension and epsilon is the desired precision. In contrast, the best classical algorithm for the same task requires Omega(N)polylog(1/epsilon) queries. In addition, this algorithm allows the user to select any constant success probability. We also provide a similar algorithm with the same runtime that allows us to prepare a quantum state lying mostly in the matrix's low-energy subspace. We implement simulations of both algorithms and demonstrate their application to problems in quantum chemistry and materials science.
Keywords:
quantum algorithm
quantum information
ground state

Journal

Quantum Science and Technology cover
Quantum Science and Technology
IF:
5
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1.4K
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U
University of Padua
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Ecole Polytechnique Federale de Lausanne
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U
University of Waterloo
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Perimeter Institute for Theoretical Physics
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Papers: 1.6K
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