Quantum Computing Gets a 'Hard, Cold Reality Check'

A Canadian cybersecurity firm has warned that as soon as 2025, quantum computers could make current encryption methods useless. But now Slashdot reader christoban shares a "reality check" - an IEEE Spectrum takedown with the tagline "Hype is everywhere, skeptics say, and practical applications are still far away."The quantum computer revolution may be further off and more limited than many have been led to believe. That's the message coming from a small but vocal set of prominent skeptics in and around the emerging quantum computing industry... [T]here's growing pushback against what many see as unrealistic expectations for the technology. Meta's head of AI research Yann LeCun recently made headlines after pouring cold water on the prospect of quantum computers making a meaningful contribution in the near future. Speaking at a media event celebrating the 10-year anniversary of Meta's Fundamental AI Research team he said the technology is "a fascinating scientific topic," but that he was less convinced of "the possibility of actually fabricating quantum computers that are actually useful." While LeCun is not an expert in quantum computing, leading figures in the field are also sounding a note of caution. Oskar Painter, head of quantum hardware for Amazon Web Services, says there is a "tremendous amount of hype" in the industry at the minute and "it can be difficult to filter the optimistic from the completely unrealistic." A fundamental challenge for today's quantum computers is that they are very prone to errors. Some have suggested that these so-called "noisy intermediate-scale quantum" (NISQ) processors could still be put to useful work. But Painter says there's growing recognition that this is unlikely and quantum error-correction schemes will be key to achieving practical quantum computers. The leading proposal involves spreading information over many physical qubits to create "logical qubits" that are more robust, but this could require as many as 1,000 physical qubits for each logical one. Some have suggested that quantum error correction could even be fundamentally impossible, though that is not a mainstream view. Either way, realizing these schemes at the scale and speeds required remains a distant goal, Painter says... "I would estimate at least a decade out," he says. A Microsoft technical fellow believes there's fewer applications where quantum computers can really provide a meaningful advantage, since operating a qubit its magnitudes slower than simply flipping a transistor, which also makes the throughput rate for data thousands or even millions of times slowers. "We found out over the last 10 years that many things that people have proposed don't work," he says. "And then we found some very simple reasons for that."

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