In the third instalment of his exclusive monthly series for the South China Morning Post, American theoretical physicist and Nobel laureate Frank Wilczek discusses the significance of Google’s new Willow chip and provides a reality check on the state of quantum computing. Read the previous articles here.
On December 9, Google released a new computer chip named “Willow”. It is the central processor – basically, the brain – of the latest and (so far) greatest quantum computer. By showing a clear advantage over conventional supercomputers in a specially crafted mathematical task, and by doing meaningful error correction, Willow achieved two long-sought goals in the field. How important are those achievements, and what do they mean for the future?
First, just what is a quantum computer?
Physicists today believe quantum mechanics describes the behaviour of all matter. And the creative engineers who use beautifully crafted, focused lasers to sculpt the trillions of tiny, delicate semiconductor transistors at the heart of “conventional’’ modern computers – from laptops to workstations to supercomputers – are virtuoso users of quantum mechanics. In those important ways, all modern computers are quantum computers.
But the phrase “quantum computer”, as it is commonly used today, means something more special and specific. Quantum computers, in this usage, are computers capable of using superpositions of different logical states. Let me spell out those two key ideas.
