Solving 1D Poisson problem with a Variational Quantum Linear Solver

Fuente: arXiv
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Hauptverfasser: Balducci, Giorgio Tosti, Chen, Boyang, Möller, Matthias, De Breuker, Roeland
Format: Preprint
Veröffentlicht: 2024
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author Balducci, Giorgio Tosti
Chen, Boyang
Möller, Matthias
De Breuker, Roeland
author_facet Balducci, Giorgio Tosti
Chen, Boyang
Möller, Matthias
De Breuker, Roeland
contents Different hybrid quantum-classical algorithms have recently been developed as a near-term way to solve linear systems of equations on quantum devices. However, the focus has so far been mostly on the methods, rather than the problems that they need to tackle. In fact, these algorithms have been run on real hardware only for problems in quantum physics, such as Hamiltonians of a few qubits systems. These problems are particularly favorable for quantum hardware, since their matrices are the sum of just a few unitary terms and since only shallow quantum circuits are required to estimate the cost function. However, for many interesting problems in linear algebra, it appears far less trivial to find an efficient decomposition and to trade it off with the depth of the cost quantum circuits. A first simple yet interesting instance to consider are tridiagonal systems of equations. These arise, for instance, in the discretization of one-dimensional finite element analyses. This work presents a method to solve a class of tridiagonal systems of equations with the variational quantum linear solver (VQLS), a recently proposed variational hybrid algorithm for solving linear systems. In particular, we present a new decomposition for this class of matrices based on both Pauli strings and multi--qubit gates, resulting in less terms than those obtained by just using Pauli gates. Based on this decomposition, we discuss the tradeoff between the number of terms and the near-term implementability of the quantum circuits. Furthermore, we present the first simulated and real-hardware results obtained by solving tridiagonal linear systems with VQLS, using the decomposition proposed.
format Preprint
id arxiv_https___arxiv_org_abs_2412_04938
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Solving 1D Poisson problem with a Variational Quantum Linear Solver
Balducci, Giorgio Tosti
Chen, Boyang
Möller, Matthias
De Breuker, Roeland
Computational Engineering, Finance, and Science
Numerical Analysis
Different hybrid quantum-classical algorithms have recently been developed as a near-term way to solve linear systems of equations on quantum devices. However, the focus has so far been mostly on the methods, rather than the problems that they need to tackle. In fact, these algorithms have been run on real hardware only for problems in quantum physics, such as Hamiltonians of a few qubits systems. These problems are particularly favorable for quantum hardware, since their matrices are the sum of just a few unitary terms and since only shallow quantum circuits are required to estimate the cost function. However, for many interesting problems in linear algebra, it appears far less trivial to find an efficient decomposition and to trade it off with the depth of the cost quantum circuits. A first simple yet interesting instance to consider are tridiagonal systems of equations. These arise, for instance, in the discretization of one-dimensional finite element analyses. This work presents a method to solve a class of tridiagonal systems of equations with the variational quantum linear solver (VQLS), a recently proposed variational hybrid algorithm for solving linear systems. In particular, we present a new decomposition for this class of matrices based on both Pauli strings and multi--qubit gates, resulting in less terms than those obtained by just using Pauli gates. Based on this decomposition, we discuss the tradeoff between the number of terms and the near-term implementability of the quantum circuits. Furthermore, we present the first simulated and real-hardware results obtained by solving tridiagonal linear systems with VQLS, using the decomposition proposed.
title Solving 1D Poisson problem with a Variational Quantum Linear Solver
topic Computational Engineering, Finance, and Science
Numerical Analysis
url https://arxiv.org/abs/2412.04938