It looks like we're taking a gamble, but will it be a winner or a loser?

Australia is making a billion-dollar bet on a 'useful' quantum computer. So what are we buying?

Three years from now, if all goes to plan, an industrial estate near Brisbane Airport will house an enormous quantum computer: one of the most complex machines ever built.

From the outside, it'll be a hangar topped with a plume of white steam from its cryogenic freezers.

Inside, it'll be like nothing else on Earth: racks of cabinets cooled to the temperature of outer space, holding custom-built silicon wafers that can detect individual photons, particles that have no mass and are also (confusingly) waves.

The Californian start-up behind the machine, PsiQuantum, says it will be world's first useful quantum computer, able to solve problems conventional computers cannot.

All up, it will cost more than $1 billion. Most of that will come from taxpayers, thanks to a massive investment from the Queensland and federal governments........