You can think of qubits as a globe, with 1 at the North Pole, 0 at the South Pole, and superposition at any other point on the planet. Instead of bits, which can only be 1 or 0, these components – which would eventually become known as quantum bits, or 'qubits' – can be 1, 0, or in a state of superposition where they are both 1 and 0 at the same time. He realised that a computer built from quantum components could be so much more powerful than just a physics simulator. In 1985, Oxford-based physicist David Deutsch went a step further than Feynman. After that, there was nowhere left for computers to go but into the quantum realm. In 2012, Australian researchers created a transistor that consisted of a single atom, switching between two states to signify 1s and 0s. However, the pace of change predicted by Moore’s Law – a doubling of the number of transistors on a microchip every two years – is slowing down. We’ve gone from vacuum tubes in room-sized machines to billions of microscopic transistors on silicon. Modelling complex interactions between molecules, as Feynman wanted to, creates the same problem – with every variable you add, the challenge gets bigger.įor decades, chipmakers have been dealing with this problem by packing more and more bits into processors, by making the physical switches that control them smaller. A classical device trying to plot the best route has to check every single possible order in which you could visit the cities, so for every stop you add to the journey, the amount of computing power balloons – 11 cities have 20 million routes between them, 12 cities have 240 million routes, 15 cities have more than 650 billion. This is the iconic travelling salesman problem, the kind of situation where a quantum computer could prove invaluable. “But if I made it 22 cities, using the same algorithm and the same laptop, it would take 2,000 years.” “Say we want to send you from the UK to 14 cities in the US, and work out the optimal path – my laptop can do that in a second,” explains William 'Whurley' Hurley, founder of Strangeworks, a company that aims to make quantum computing more accessible. We walk past surfboards hanging on the wall and a group of men playing Super Smash Bros in a meeting room named after Nobel prize-winning physicist Richard Feynman, to the fridges – suspended from the ceiling like chandeliers: gold-plated copper discs and intricate wiring narrow to a point inside nested canisters, each painted in one of Google’s corporate colours. There are five of these inside the squat, beige building behind us. The chip, no bigger than a thumbnail, sits at the bottom of a huge cryostat that keeps it chilled to a temperature colder than outer space. The team went back to the drawing board, and by June 7 they had redesigned the task, which they programmed into the Sycamore quantum processor.

“I was like, really? I’ve been gone a week!” he laughs.

Anthony Megrant, a quantum hardware engineer who fell into the field after a stint in the US army, had returned from paternity leave in early June to find the lab in a fluster. Seven months later, Boixo – smartly dressed in chinos and a pink sweater – is sitting on a picnic bench outside Google’s Santa Barbara lab, joking with his colleagues about the brief setback. “I was panicking a little bit,” Boixo says.

Their quantum chip wasn’t going to be able to beat that. But then, on May 31, a parallel team inside Google discovered that the task was actually a million times easier for a classical computer than had been thought. The simulations looked good, and by the end of April 2019, Google seemed on the verge of achieving quantum supremacy. But there was a problem.īoixo, a tall Spaniard with a greying beard, had designed an experiment that was meant to be virtually impossible for a classical computer to solve, but easy for Google’s Sycamore quantum chip. The group, split across two sites in southern California, had spent the better part of a decade trying to build a working quantum computer – a revolutionary type of device that works according to the laws of quantum mechanics.įor months, Google had been inching closer to a milestone known as quantum supremacy – the point at which a quantum computer can accomplish something beyond even the world’s best classical supercomputers. On June 4, 2019, Sergio Boixo gathered his colleagues on Google’s quantum research team together for an urgent meeting.

Microsoft big quantum error after all