Variational Quantum Harmonizer: Generating Chord Progressions and Other Sonification Methods with the VQE Algorithm

TL;DR

This paper introduces the Variational Quantum Harmonizer, a musical interface that uses the VQE algorithm to sonify quantum optimization processes, enabling novel musical creation and data visualization through quantum-inspired methods.

Contribution

It presents a new musical interface leveraging VQE intermediary states for sonification, combining quantum optimization with artistic sound design.

Findings

Demonstrated sonification of VQE iterative states

Created a prototype for quantum-inspired musical composition

Showcased artistic and data visualization applications

Abstract

This work investigates a case study of using physical-based sonification of Quadratic Unconstrained Binary Optimization (QUBO) problems, optimized by the Variational Quantum Eigensolver (VQE) algorithm. The VQE approximates the solution of the problem by using an iterative loop between the quantum computer and a classical optimization routine. This work explores the intermediary statevectors found in each VQE iteration as the means of sonifying the optimization process itself. The implementation was realised in the form of a musical interface prototype named Variational Quantum Harmonizer (VQH), providing potential design strategies for musical applications, focusing on chords, chord progressions, and arpeggios. The VQH can be used both to enhance data visualization or to create artistic pieces. The methodology is also relevant in terms of how an artist would gain intuition towards achieving a desired musical sound by carefully designing QUBO cost functions. Flexible mapping strategies could supply a broad portfolio of sounds for QUBO and quantum-inspired musical compositions, as demonstrated in a case study composition, "Dependent Origination" by Peter Thomas and Paulo Itaborai.