It sounds like a pinball machine heard through a couple of tin cans and a bit of string, but that is actually the pinging noise of individual ions (charged phosphorous atoms) being fired into a silicon chip. And it’s the first step in an Australian quest to build a quantum computer based on silicon chips. The physics equation that describes what you’re hearing is simpler than most — “one ping = one atom” says Professor David Jamieson, who headed up the research.