The Variational Quantum Harmonizer Developing a Framework for Sonifying Variational Quantum Algorithms: Implications for Music Composition
Paulo Vitor Itaborai, Peter Thomas, Arianna Crippa, Karl Jansen, Tim Schwägerl, Maria Aguado Yanez
Published in Advances in Quantum Computer Music, World Scientific, editor E. R. Miranda, 2024.
DOI:10.1142/14025Quantum Computer Music (Springer, 2024)
arXiv:2409.07104
This chapter examines the Variational Quantum Harmonizer, a software tool and musical interface that focuses on the problem of sonification of the minimization steps of Variational Quantum Algorithms (VQA), used for simulating properties of quantum systems and optimization problems assisted by quantum hardware. Particularly, it details the sonification of Quadratic Unconstrained Binary Optimization (QUBO) problems using VQA. A flexible design enables its future applications both as a sonification tool for auditory displays in scientific investigation, and as a hybrid quantum-digital musical instrument for artistic endeavours. In turn, sonification can help researchers understand complex systems better and can serve for the training of quantum physics and quantum computing. The VQH structure, including its software implementation, control mechanisms, and sonification mappings are detailed. Moreover, it guides the design of QUBO cost functions in VQH as a music compositional object. The discussion is extended to the implications of applying quantum-assisted simulation in quantum-computer aided composition and live-coding performances. An artistic output is showcased by the piece \textit{Hexagonal Chambers} (Thomas and Itaboraí, 2023).
A quantum computing algorithm for rhythm generation is presented, which aims to expand and explore quantum computing applications in the arts, particularly in music. The algorithm maps quantum random walk trajectories onto a rhythmspace -- a 2D interface that interpolates rhythmic patterns. The methodology consists of three stages. The first stage involves designing quantum computing algorithms and establishing a mapping between the qubit space and the rhythmspace. To minimize circuit depth, a decomposition of a 2D quantum random walk into two 1D quantum random walks is applied. The second stage focuses on biasing the directionality of quantum random walks by introducing classical potential fields, adjusting the probability distribution of the wave function based on the position gradient within these fields. Four potential fields are implemented: a null potential, a linear field, a Gaussian potential, and a Gaussian potential under inertial dynamics. The third stage addresses the sonification of these paths by generating MIDI drum pattern messages and transmitting them to a Digital Audio Workstation (DAW). This work builds upon existing literature that applies quantum computing to simpler qubit spaces with a few positions, extending the formalism to a 2D x-y plane. It serves as a proof of concept for scalable quantum computing-based generative random walk algorithms in music and audio applications. Furthermore, the approach is applicable to generic multidimensional sound spaces, as the algorithms are not strictly constrained to rhythm generation and can be adapted to different musical structures.
See also:
Itaborai, P. V., Schwäerl, T., Yanez, M. A., Crippa, A., Jansen, K., Miranda, E. R., and Thomas, P. (2023a).
Variational quantum harmonizer: Gener- ating chord progressions and other sonification methods with the vqe algo- rithm, in 2nd International Symposium on Quantum Computing and Mu- sical Creativity (ISQCMC Berlin) (Zenodo), doi:10.5281/zenodo.10206731, https://doi.org/10.5281/zenodo.10206731
The first quantum music book where we contributed a chapter
The Springer publication on quantum computer music
A Qeyboard and listening to physical models, was fun! New Directions in Quantum Music: concepts for a quantum keyboard and the sound of the Ising model
Giuseppe Clemente, Arianna Crippa, Karl Jansen, Cenk Tüysüz
Published in "Quantum Computer Music" (Springer, 2022), Edited by Miranda, E. R
arXiv:2204.00399
This work is a contributed chapter of the above mentioned book
Figure:
A complex synthesis for three sounds played simultaneously
with both evolving frequencies and intensities with some smoothing applied and synthetized
with sampling rate 44100 Hz.
Abstract
We explore ideas for generating sounds and eventually music by using quantum devices in the NISQ era using quantum circuits. In particular, we first consider a concept for a "qeyboard", i.e. a quantum keyboard, where the real-time behaviour of expectation values using a time evolving quantum circuit can be associated to sound features like intensity, frequency and tone.
Then, we examine how these properties can be extracted from physical quantum systems, taking the Ising model as an example. This can be realized by measuring physical quantities of the quantum states of the system, e.g. the energies and the magnetization obtained via variational quantum simulation techniques.
