May 2, 2023
Sam Learner in New York, John Thornhill, Sam Joiner and Irene de la Torre Arenas in London
For the moment, quantum computers, which exploit the spooky physics of subatomic particles, remain too unstable to perform sophisticated operations for long. IBM’s Osprey computer, thought to be the most powerful quantum computer yet developed, only has 433 qubits (or quantum bits) when most computer scientists consider it would take 1mn to realise the technology’s potential. That may still be a decade away.
But in 1994 the American mathematician Peter Shor wrote an algorithm that could theoretically run on a powerful quantum computer to crack the RSA encryption protocol most commonly used to secure online transactions. The RSA algorithm exploits the fact that while it is very easy to multiply two large prime numbers, it is very difficult for a classical computer to take the result and perform the calculation in reverse. Shor showed how a quantum computer could do so relatively easily. A recent research paper published in China explored the possibility that a hybrid classical-quantum computing approach might be able to pull Q-day forward.
Excited by the possibilities of building the first robust quantum computer, and terrified by the prospect of coming second, the world’s leading powers are now in a race to develop the technology. Not only can quantum computers be used to crack existing encryption methods, they can also be used to secure communications in a quantum world — and governments, corporations and venture capitals have been investing heavily with a view to commercialising the technology.
But how does quantum computing actually work? To understand the answer, first you need to understand how a classical computer functions.
Additional Reporting by Josh Gabert-Doyon and Edwin Lane. Additional development by Emma Lewis. With thanks to Peter Sigrist, Glenn Manoff and Ben Barber.
LINK: https://ig.ft.com/quantum-computing/
Image: A look inside a decommissioned IBM 1 quantum computer © Charlie Bibby/FT