Computers and digital technology are central to the modern music industry – but what could quantum computers bring to the party? Philip Ball tunes in to an avant-garde band of musicians and scientists who are exploring how quantum computing can be used to make and manipulate music
The Goethe-Institut, opposite Imperial College in London, is not the kind of place you would expect to encounter cutting-edge avant-garde art. With its Neoclassical façade and a history of providing German language classes, it hardly seems the type of venue to host an event that includes musicians like Peter Gabriel and Brian Eno, along with a number of quantum physicists. But the sounds emanating from its lecture theatre last December were a far cry from the institute’s traditional image: drones, bleeps and bursts of wild beats more akin to the soundtrack of an experimental underground movie.
This was, in fact, the sound of quantum computing.
The event was attended by about 150 people, who were listening to an improvised musical performance orchestrated by the Brazilian composer and computer scientist Eduardo Reck Miranda, who is based at the University of Plymouth in the UK. In one piece, Miranda and two colleagues were each using their own laptops, which were connected to a quantum computer over the Internet, to control – via hand gestures – the state of a quantum bit (qubit). When that state was measured, the result dictated the characteristics of the sounds created by synthesizers back in London.
If that sounds bizarre – well, yes it truly did.
“I want to develop machines that will help me be creative and will challenge my normal way of doing things”
—Eduardo Miranda, University of Plymouth
In quantum computing, information is encoded in superposition states of entangled qubits, which allows some calculations to be carried out far more efficiently than is possible with classical machines. Although these devices are still prototypes mostly confined to the laboratories of tech giants such as IBM and Google, composers like Miranda are keen to discover what the new technology can offer them. “I want to develop machines that will help me be creative and will challenge my normal way of doing things,” he says.
Quantum computing, Miranda believes, “promotes a different way of thinking, [which in turn] will lead to different ways of thinking about music.” It’s a view shared by Bob Coecke – another of Miranda’s collaborators – who is a physicist at the Oxford-based quantum computing company Quantinuum. “If you change the way you look at things, and the language you use, you come out with completely new ideas,” says Coecke.
“I’m fascinated to know how [this music] works.”
—Brian Eno, musician
Quantum music is currently a decidedly niche field – but one that is attracting some high-profile interest. Indeed the Goethe-Institut event was convened to mark the launch of a new book edited by Miranda, Quantum Computer Music, which claims to be the first-ever book on the subject (Springer, 2022). Coecke, meanwhile, is planning a quantum art/science mash-up in Oxford this year with Miranda and the Italian theorist Carlo Rovelli.
“I’m fascinated to know how [this music] works,” said Eno after the Goethe-Institut performance in an interview with the institute. “It’s difficult for me to make a judgement, because you don’t know how much of those decisions were made by humans, and how much is coming out of that different kind of intelligence.”
A new kind of music
Harnessing quantum computing for making music is “like learning how to play a new musical instrument” says Maria Mannone, a theoretical physicist working on quantum information at the University of Palermo in Italy, who is also a composer. “We have to learn how to play the music we want, but, at the same time, the specific features of the new instrument can create constraints and suggest particular ideas.”
Miranda suspects that one way to exploit the possibilities is to get a quantum computer to come up with unexpected musical fragments that provide the kernels of ideas for the composer to develop, rather in the way in which AI-generated music is currently being used. “I’m trying,” he says, “to get the machine to give me material that I wouldn’t come up with myself – ideas that I can work with.”
“Everything, especially in the sciences, can be a source of inspiration”
—Maria Mannone, University of Palermo, Italy
One of the current obstacles to the expansion of the field is the sheer unfamiliarity and technical complexity of quantum mechanics itself. Miranda’s new book Quantum Computer Music is not a manual for the faint-hearted, being filled with wavefunctions and matrix algebra. Musicians will be daunted, while the physicists and engineers who understand the theory tend to have little knowledge of musical traditions.
But he hopes that user-friendly interfaces will be developed that will lower the entry barrier, just as they have for computing generally. Miranda’s qubit rotations, for example, are controlled by simple hand gestures, rather like the way in which the theremin – an electronic musical instrument – is played.
Another approach is being pioneered by Jim Weaver, a quantum scientist at IBM’s Yorktown Heights Research Center in New York, who has developed the Quantum Toy Piano. It’s a musical tool that uses a quantum computer to generate melodies and harmonies probabilistically, using the inherent randomness of measuring qubit states to assign the notes.
Hear all about it
If you’re wondering where you might be able to hear quantum music for yourself, Miranda has his sights set on a live performance at a concert hall through a forthcoming collaboration with the London Sinfonietta. He also foresees this kind of composing infiltrating less formal settings such as clubs, perhaps via the “live coding” movement, a new performance art in which DJ-like coders write programs to control audio-visual media in an improvised and interactive way, perhaps combined with dance, poetry and music (you can listen to an example at bit.ly/3Z8hUDg).
To stimulate the growth of the community, in November 2021 Miranda collaborated with IBM Quantum and Quantinuum to host the first International Symposium on Quantum Computing and Musical Creativity. “We don’t yet know what the possibilities for quantum music are,” said Quantinuum’s founding chief executive Ilyas Khan in the Goethe-Institut event – and it may be that as quantum music matures it will bear little resemblance to what today’s pioneers are doing. “These first two to three years are experimental,” he says.
Miranda hopes that it might become possible to express – in sound – quantum concepts such as entanglement and coherence that are hard to intuit intellectually. “That’s the holy grail,” he says. “I want to achieve this but I don’t know how.” But for Coecke, it’s all about catalysing a switch to quantum thinking. “If you put things together in the quantum world, suddenly a new universe of possibilities emerges.”