A hybrid classical-quantum algorithm for solution of nonlinear ordinary differential equations

TL;DR

This paper introduces a hybrid classical-quantum method using Walsh-Hadamard basis functions to efficiently solve nonlinear ordinary differential equations, achieving lower computational complexity than classical methods.

Contribution

It presents a novel hybrid quantum-classical algorithm leveraging quantum Walsh-Hadamard transforms for solving nonlinear differential equations with improved efficiency.

Findings

Hybrid approach reduces computational complexity to O(N)

Results are comparable to classical solutions for simple cases

New insights into Walsh functions and finite group representations

Abstract

A hybrid classical-quantum approach for the solution of nonlinear ordinary differential equations using Walsh-Hadamard basis functions is proposed. Central to this hybrid approach is the computation of the Walsh-Hadamard transform of arbitrary vectors, which is enabled in our framework using quantum Hadamard gates along with state preparation, shifting, scaling, and measurement operations. It is estimated that the proposed hybrid classical-quantum approach for the Walsh-Hadamard transform of an input vector of size N results in a considerably lower computational complexity (O(N) operations) compared to the Fast Walsh-Hadamard transform (O(N log2(N)) operations). This benefit will also be relevant in the context of the proposed hybrid classical-quantum approach for the solution of nonlinear differential equations. Comparisons of results corresponding to the proposed hybrid classical-quantum approach and a purely classical approach for the solution of nonlinear differential equations (for cases involving one and two dependent variables) were found to be satisfactory. Some new perspectives relevant to the natural ordering of Walsh functions (in the context of both classical and hybrid approaches for the solution of nonlinear differential equations) and representation theory of finite groups are also presented here.