Phonons are the fundamental quantum units that make up sound waves, in much the same way that photons make up light beams.
A weird and wonderful array of technologies are competing to become the standard-bearer for quantum computing. The latest contender wants to encode quantum information in sound waves. One thing all quantum computers have in common is the fact that they manipulate information encoded in quantum states. But that's where the similarities end, because those quantum states can be induced in everything from superconducting circuits to trapped ions, ultra-cooled atoms, photons, and even silicon chips. While some of these approaches have attracted more investment than others, we're still a long way from the industry settling on a common platform. And in the world of academic research, experimentation still abounds. Now, a team from the University of Chicago has taken crucial first steps towards building a quantum computer that can encode information in phonons, the fundamental quantum units that make up sound waves in much the same way that photons make up light beams. The basic principles of how you could create a "phononic" quantum computer are fairly similar to those used in "photonic" quantum computers. Both involve generating and detecting individual particles, or quasiparticles, and manipulating them using beamsplitters and phase shifters. Phonons are quasiparticles, because although they act like particles as far as quantum mechanics are concerned, they are actually made up of the collective behavior of large numbers of atoms. The group from Chicago had already demonstrated that they could generate individual phonons using surface acoustic waves, which travel along the surface of a material at frequencies roughly a million times…