All over the world, scientists are busy trying to build quantum computers. What the photonic muck is a quantum computer? And why do you need dental floss to make one? How come it looks like a steampunk chandelier? And sounds like an armoured Morris dancer on a punctured spacehopper? Do they really work in parallel universes? And what's all this about quantum supremacy? Does it mean we'll soon have to submit to an army of quantum robot overlords? In this episode, we answer all these questions and more with the help of top quantum physicists including Dr Jerry Chow of IBM, Professor John Martinis of Google and Professor Simon Benjamin of Oxford University. And we drop in on The Pub Landlord, Al Murray, to see if he has any pressing questions about this exciting new technology...