Q1Synth: A Quantum Computer Musical Instrument

Abstract

<jats:p>This paper introduces Q1Synth, an unprecedented musical instrument that produces sounds from (a) quantum state vectors representing the properties of a qubit, and (b) its measurements. The instrument is presented on a computer screen (or mobile device, such as a tablet or smartphone) as a Bloch sphere, which is a visual representation of a qubit. The performer plays the instrument by rotating this sphere using a mouse. Alternatively, a gesture controller can be used, e.g., a VR glove. While the sphere is rotated, a continuously changing sound is produced. The instrument has a ‘measure key’. When the performer activates this key, the instrument generates a program (also known as a quantum circuit) to create the current state vector. Then, it sends the program to a quantum computer over the cloud for processing, that is, measuring, in quantum computing terminology. The computer subsequently returns the measurement, which is also rendered into sound. Currently, Q1Synth uses three different techniques to make sounds: frequency modulation (FM), subtractive synthesis, and granular synthesis. The paper explains how Q1Synth works and details its implementation. A setup developed for a musical performance, Spinnings, with three networked Q1Synth instruments is also reported. Q1Synth and Spinnings are examples of how creative practices can open the doors to new application pathways for quantum computing technology. Additionally, they illustrate how such emerging technology is leading to new approaches to musical instrument design and musical creativity.</jats:p>