China Claims To Have Made Major Quant Computer Breakthrough But Western Experts Say Any Commercial Benefits Still Years Away – Slashdot

Are today’s rudimentary quantum computers already on the verge of significant feats beyond the reach of traditional computers? Or have their capabilities been exaggerated, as practical uses for the technology recede into the future? From a report: These questions have been thrown into sharp relief in recent days by a claim from a group of Chinese researchers to have come up with a way to break the RSA encryption that underpins much of today’s online communications. The likelihood that quantum computers would be able to crack online encryption was widely believed a danger that could lie a decade or more in the future. But the 24 researchers, from a number of China’s top universities and government-backed laboratories, said their research showed it could be possible using quantum technology that is already available.

The quantum bits, or qubits, used in today’s machines are highly unstable and only hold their quantum states for extremely short periods, creating “noise.” As a result, “errors accumulate in the computer and after around 100 operations there are so many errors the computation fails,” said Steve Brierley, chief executive of quantum software company Riverlane. That has led to a search for more stable qubits as well as error-correction techniques to overcome the “noise,” pushing back the date when quantum computers are likely to reach their full potential by many years.

The Chinese claim, by contrast, appeared to be an endorsement of today’s “noisy” systems, while also prompting a flurry of concern in the cyber security world over a potentially imminent threat to online security. By late last week, a number of researchers at the intersection of advanced mathematics and quantum mechanics had thrown cold water on the claim. Brierley at Riverlane said it “can’t possibly work” because the Chinese researchers had assumed that a quantum computer would be able to simply run a vast number of computations simultaneously, rather than trying to gain an advantage through applying the system’s quantum properties.

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