Rivals rubbish Google’s claim of quantum supremacy

A significant scientific breakthrough that represents the dawn of computing’s second era? Or a head-turning piece of research with little practical application?

Researchers at Google say they have built the first quantum computer that can perform a calculation far beyond the reach of even the most powerful machine built along traditional, or “classical”, lines — a long-awaited feat known as “quantum supremacy”.

The company’s researchers call it a “milestone” that “heralds the advent of a much-anticipated computing paradigm”. By harnessing the quantum effects exhibited by subatomic particles, such systems have the potential — at least in theory — to leap far ahead of today’s supercomputers.

But not everyone is ready to call this a turning point for computer science. Google’s claim is “indefensible — it’s just plain wrong”, said Dario Gil, head of research at IBM, one of the competitors in the race to achieve quantum computing.

While crediting some of the internet company’s technical advances, he dismisses the claim that this is a seminal moment for computing as “grandiosity”. The research is just “a laboratory experiment designed to essentially — and almost certainly exclusively — implement one very specific quantum sampling procedure with no practical applications,” he said.

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Others working in the field, however, are more willing to back Google’s claims. Its research is “profound”, said Chad Rigetti, a former IBM executive who now heads a quantum computing start-up. “It’s very important for the industry to hit this milestone. It’s a big moment for humans and for science.”

Google claimed its breakthrough in a research paper headlined “Quantum supremacy using a programmable superconducting processor”. First reported by the FT, it was briefly posted on a Nasa website last week before being removed, and the company has not said when it will be formally published.

Unlike the bits in a digital computer, which register either a 1 or 0, quantum bits — known as qubits — can be both at the same time. Along with another quantum phenomenon known as entanglement, through which qubits can influence others they are not even connected to, this opens the way to systems that can handle massively more complex problems.

Part of the controversy in the computing world lies in the term quantum supremacy. Coined in 2012 by theoretical physicist John Preskill, it denotes the moment when a system built using the new technology can solve a problem that is, for all practical purposes, impossible for even the most powerful supercomputers to handle.