Explained | Quantum computers can work with light. Can they work with sound, too? Premium

Can we build a quantum computer whose information unit is, colloquially speaking, sound? According to a paper published in Science this month, it should be possible. The problem is that researchers can manipulate electrons using electric currents, magnetic fields, etc., and they can manipulate photons with mirrors, lenses, etc. – but what can they manipulate phonons with? To this end, in the new study, researchers from the University of Chicago have reported developing an acoustic beam-splitter.

One of the two big news items these days from the realm of computing is quantum computers (the other is artificial intelligence). Recently, IBM published a paper in which it claimed to have demonstrated that a quantum computer could solve a useful problem that today’s conventional computers can’t, a result merited by concerns that their computations might become too unreliable when they also become complicated.

What are qubits?

Quantum computers use qubits as their basic units of information. A qubit can be a particle – like an electron; a collection of particles; or a quantum system engineered to behave like a particle. Particles can do funky things that large objects – like the semiconductors of classical computers – can’t because they are guided by the rules of quantum physics. These rules allow each qubit to have the values ‘on’ and ‘off’ at the same time, for example.

The premise of quantum computing is that information can be ‘encoded’ in some property of the particle, like an electron’s spin, and then processed using these peculiar abilities. As a result, quantum computers are expected to perform complicated calculations that are out of reach of the best supercomputers today.

Other forms of quantum computing use other units of information. For example, linear optical quantum computing (LOQC) uses photons, the particles of light, as qubits. Just like different pieces of information can be combined and processed by encoding them on electrons and then having the electrons interact in different ways, LOQC offers to use optical equipment – like mirrors, lenses, splitters, waveplates, etc. – with photons to process information.

In fact, any particle that can be controlled and manipulated using quantum-mechanical phenomena should, on paper, be usable as an information unit in a quantum computer.

What are phonons?