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A comment on Looking at some claims that quantum computers won't work.

Re:Looking at some claims that quantum computers won't work by peepeepoopoo101 on Saturday January 18, 2025 @05:36PM (#42751979)
There's an awful lot of handwaving in this blog post. I'm sorry, but I'm not convinced. The author mentions how some devices that can seemingly solve exponential time complexity problems also require exponentially high precision, but there doesn't seem to be a strong argument for why that doesn't apply to quantum computers. We haven't experimentally demonstrated quantum computing at sufficient scales to prove that the required number of physical qubits to perform error correction doesn't scale exponentially.
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Re:Looking at some claims that quantum computers won't work by plumthreads on Saturday January 18, 2025 @05:57PM (#42752099)
I got the impression that DJB was criticizing the arguments for why quantum computers won't work. Not trying to demonstrate why they will work.
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Re:Looking at some claims that quantum computers won't work by gjvc on Saturday January 18, 2025 @08:59PM (#42752972)
yup
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Re:Looking at some claims that quantum computers won't work by wzeng on Saturday January 18, 2025 @07:16PM (#42752539)
We don’t need exponentially more physical qubits because we have quantum error correction schemes that exponentially decrease the logical error rate with only a polynomial increase in the number of qubits. There are in fact many schemes for this (https://errorcorrectionzoo.org/) with the surface code mentioned in the blog being a leading approach.

Details for how this could work for factoring are here: https://arxiv.org/abs/1905.09749

There will be engineering challenges to scale up these implementations but in principal you shouldn’t need exponential resources (unless there is something wrong with quantum mechanics). This sort of error correction scaling does not exist, for example, for analog computing.

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Re:Looking at some claims that quantum computers won't work by Yoric on Saturday January 18, 2025 @05:59PM (#42752112)
Note that you do not need error correction for quantum computing. You only need it for digital quantum computing. There's a separate branch, analog quantum computing, that is also very promising.
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Re:Looking at some claims that quantum computers won't work by Yoric on Sunday January 19, 2025 @06:51AM (#42756257)
Does anybody want to elaborate why I'm being downvoted?

For context, there are several companies selling analog quantum computers, e.g. Pasqal, D-Wave.

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Re:Looking at some claims that quantum computers won't work by abdullahkhalids on Sunday January 19, 2025 @11:57AM (#42758764)
What D-Wave has is not a quantum computer, in the sense that it (the computer architecture) can't solve BQP problems efficiently. They are widely considered shills by the quantum computing community.
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Re:Looking at some claims that quantum computers won't work by rq1 on Saturday January 18, 2025 @05:52PM (#42752076)
The author is DJB.
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Re:Looking at some claims that quantum computers won't work by sebmellen on Saturday January 18, 2025 @05:54PM (#42752083)
For those not familiar: https://en.m.wikipedia.org/wiki/Daniel_J._Bernstein
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Re:Looking at some claims that quantum computers won't work by gjvc on Saturday January 18, 2025 @08:59PM (#42752967)
I think you've missed the point of it then.
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