Variational quantum algorithm for generalized eigenvalue problems and its application to the finite element method

Fuente: arXiv
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Main Authors: Sato, Yuki, Watanabe, Hiroshi C., Raymond, Rudy, Kondo, Ruho, Wada, Kaito, Endo, Katsuhiro, Sugawara, Michihiko, Yamamoto, Naoki
Format: Preprint
Published: 2023
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_version_ 1866910448637444096
author Sato, Yuki
Watanabe, Hiroshi C.
Raymond, Rudy
Kondo, Ruho
Wada, Kaito
Endo, Katsuhiro
Sugawara, Michihiko
Yamamoto, Naoki
author_facet Sato, Yuki
Watanabe, Hiroshi C.
Raymond, Rudy
Kondo, Ruho
Wada, Kaito
Endo, Katsuhiro
Sugawara, Michihiko
Yamamoto, Naoki
contents Generalized eigenvalue problems (GEPs) play an important role in the variety of fields including engineering, machine learning and quantum chemistry. Especially, many problems in these fields can be reduced to finding the minimum or maximum eigenvalue of GEPs. One of the key problems to handle GEPs is that the memory usage and computational complexity explode as the size of the system of interest grows. This paper aims at extending sequential quantum optimizers for GEPs. Sequential quantum optimizers are a family of algorithms that iteratively solve the analytical optimization of single-qubit gates in a coordinate descent manner. The contribution of this paper is as follows. First, we formulate the GEP as the minimization/maximization problem of the fractional form of the expectations of two Hermitians. We then showed that the fractional objective function can be analytically minimized or maximized with respect to a single-qubit gate by solving a GEP of a 4 $\times$ 4 matrix. Second, we show that a system of linear equations (SLE) characterized by a positive-definite Hermitian can be formulated as a GEP and thus be attacked using the proposed method. Finally, we demonstrate two applications to important engineering problems formulated with the finite element method. Through the demonstration, we have the following bonus finding; a problem having a real-valued solution can be solved more effectively using quantum gates generating a complex-valued state vector, which demonstrates the effectiveness of the proposed method.
format Preprint
id arxiv_https___arxiv_org_abs_2302_12602
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Variational quantum algorithm for generalized eigenvalue problems and its application to the finite element method
Sato, Yuki
Watanabe, Hiroshi C.
Raymond, Rudy
Kondo, Ruho
Wada, Kaito
Endo, Katsuhiro
Sugawara, Michihiko
Yamamoto, Naoki
Quantum Physics
Generalized eigenvalue problems (GEPs) play an important role in the variety of fields including engineering, machine learning and quantum chemistry. Especially, many problems in these fields can be reduced to finding the minimum or maximum eigenvalue of GEPs. One of the key problems to handle GEPs is that the memory usage and computational complexity explode as the size of the system of interest grows. This paper aims at extending sequential quantum optimizers for GEPs. Sequential quantum optimizers are a family of algorithms that iteratively solve the analytical optimization of single-qubit gates in a coordinate descent manner. The contribution of this paper is as follows. First, we formulate the GEP as the minimization/maximization problem of the fractional form of the expectations of two Hermitians. We then showed that the fractional objective function can be analytically minimized or maximized with respect to a single-qubit gate by solving a GEP of a 4 $\times$ 4 matrix. Second, we show that a system of linear equations (SLE) characterized by a positive-definite Hermitian can be formulated as a GEP and thus be attacked using the proposed method. Finally, we demonstrate two applications to important engineering problems formulated with the finite element method. Through the demonstration, we have the following bonus finding; a problem having a real-valued solution can be solved more effectively using quantum gates generating a complex-valued state vector, which demonstrates the effectiveness of the proposed method.
title Variational quantum algorithm for generalized eigenvalue problems and its application to the finite element method
topic Quantum Physics
url https://arxiv.org/abs/2302.12602