Weighted Approximate Quantum Natural Gradient for Variational Quantum Eigensolver

Fuente: arXiv
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Main Authors: Shi, Chenyu, Dunjko, Vedran, Wang, Hao
Format: Preprint
Published: 2025
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author Shi, Chenyu
Dunjko, Vedran
Wang, Hao
author_facet Shi, Chenyu
Dunjko, Vedran
Wang, Hao
contents The variational quantum eigensolver (VQE) is one of the most prominent algorithms using near-term quantum devices, designed to find the ground state of a Hamiltonian. In VQE, a classical optimizer iteratively updates the parameters in the quantum circuit. Among various optimization methods, the quantum natural gradient descent (QNG) stands out as a promising optimization approach for VQE. However, standard QNG only leverages the quantum Fisher information of the entire system and treats each subsystem equally in the optimization process, without accounting for the different weights and contributions of each subsystem corresponding to each local term in the Hamiltonian. To address this limitation, we propose a Weighted Approximate Quantum Natural Gradient (WA-QNG) method tailored for $k$-local Hamiltonians. In this paper, we theoretically analyze the potential advantages of WA-QNG compared to QNG from three distinct perspectives and reveal its connection with the Gauss-Newton method. We also show it outperforms the standard quantum natural gradient descent in the numerical simulations for seeking the ground state of the Hamiltonian.
format Preprint
id arxiv_https___arxiv_org_abs_2504_04932
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Weighted Approximate Quantum Natural Gradient for Variational Quantum Eigensolver
Shi, Chenyu
Dunjko, Vedran
Wang, Hao
Quantum Physics
The variational quantum eigensolver (VQE) is one of the most prominent algorithms using near-term quantum devices, designed to find the ground state of a Hamiltonian. In VQE, a classical optimizer iteratively updates the parameters in the quantum circuit. Among various optimization methods, the quantum natural gradient descent (QNG) stands out as a promising optimization approach for VQE. However, standard QNG only leverages the quantum Fisher information of the entire system and treats each subsystem equally in the optimization process, without accounting for the different weights and contributions of each subsystem corresponding to each local term in the Hamiltonian. To address this limitation, we propose a Weighted Approximate Quantum Natural Gradient (WA-QNG) method tailored for $k$-local Hamiltonians. In this paper, we theoretically analyze the potential advantages of WA-QNG compared to QNG from three distinct perspectives and reveal its connection with the Gauss-Newton method. We also show it outperforms the standard quantum natural gradient descent in the numerical simulations for seeking the ground state of the Hamiltonian.
title Weighted Approximate Quantum Natural Gradient for Variational Quantum Eigensolver
topic Quantum Physics
url https://arxiv.org/abs/2504.04932