In their quest to build a silicon quantum computer, Morello and his colleagues have so far been perfecting its basic element, the "quantum bit". This is a single phosphorus atom entombed in a silicon crystal. Using a carefully tuned magnetic field, the researchers can manipulate the atom's quantum "spin", flipping it up or down.

 

That phosphorus atom is equivalent to a transistor in an ordinary computer. A transistor is on or off, which is how it represents the 1s and 0s of the binary code the computer uses to process instructions. A quantum bit is more complex. It can be spin-up, spin-down or in a "superposition" of both: 1 and 0 at the same time. Theoretically, this should enable a quantum computer to weigh multiple solutions to a complex problem at once, and solve it at phenomenal speed.

A quantum computer is "not just a 'faster' computer," Morello says. "They are the equivalent of a jet plane to a bicycle."