Four years ago, physicists at Google claimed their quantum computer could outperform classical machines — although only at a niche calculation with no practical applications. Now their counterparts at IBM say they have evidence that quantum computers will soon beat ordinary ones at useful tasks, such as calculating properties of materials or the interactions of elementary particles.
In a proof-of-principle experiment described in Nature on 14 June1, the researchers simulated the behaviour of a magnetic material on IBM’s Eagle quantum processor. Crucially, they managed to work around quantum noise — the main obstacle for this technology because it introduces errors in calculations — to get reliable results.
Their ‘error-mitigating’ techniques enabled the team to do quantum calculation “at a scale where classical computers will struggle”, says Katie Pizzolato, who heads IBM’s quantum theory group in Yorktown Heights, New York.
Although the problem they attacked uses a much-simplified, unrealistic model of a material, “It makes you optimistic that this will work in other systems and more complicated algorithms,” says John Martinis, a physicist at the University of California, Santa Barbara, who led the Google team to their 2019 milestone.
Sabrina Maniscalco, chief executive of quantum-computing start-up Algorithmiq in Helsinki, says that the experiment provides a benchmark for the state-of-the-art in quantum computers. “These machines are coming,” she says. Maniscalco's company is developing algorithms for quantum-chemistry calculations that use error mitigation.
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