We know that an ideal quantum computer provides an exponential speed-up in commercially relevant applications. There is a significant amount of smoke and mirrors in the quantum space.
Unless there is some unknown fundamental reason why we cannot realize a good-enough quantum computer with sufficient knowledge and engineering, governments and business are well-advised to invest into R&D of quantum computers.
Which is to say, just because something is possible in theory doesn't mean we have a clear idea how to get there, and if we're waiting on research breakthroughs, more money is unlikely to significantly speed up the process.
Do we know that though?
From the abstract:
> I survey, for a general scientific audience, three decades of research into which sorts of problems admit exponential speedups via quantum computers -- from the classics (like the algorithms of Simon and Shor), to the breakthrough of Yamakawa and Zhandry from April 2022. [...] I make some skeptical remarks about widely-repeated claims of exponential quantum speedups for practical machine learning and optimization problems. Through many examples, I try to convey the "law of conservation of weirdness," according to which every problem admitting an exponential quantum speedup must have some unusual property to allow the amplitude to be concentrated on the unknown right answer(s).
I am very confused at how so many people are absolutely convinced that quantum computing is known to do, or already does, all sorts of things it is not known to do. There's a sister comment here saying exponentially superior quantum computers are available in AWS!
It's like an urban legend that circulates among software engineers.
Integer factorization and quantum simulation would be two examples of commercially highly relevant applications where an exponential speed-up applies.
"Quantum simulation" is too vague to speak to applicability in any domain. There is no proven or empirically demonstrated exponential speedup on any simulation problem with known commercial applications.
https://arxiv.org/pdf/2011.06571.pdf
It does seems too good to be true.
The two caveats are
1. Only works for "mildly" nonlinear equations
2. Results are in quantum world and have to be translated back into normal deterministic world results, and this hasn't been figured out yet
Currently the choice of replacements is taking its time e.g. https://www.nist.gov/news-events/news/2022/07/nist-announces... but if tonight we'd find out that people do have sufficiently powerful quantum computers, we'd just start using one of the candidates in a jiffy)
As a parallel, on a purely theoretical level, we know how to construct a warp drive as well[1].
Solving a theoretical equation is one thing, replicating the prerequisite conditions experimentally is another entirely. Theoretically you can balance a perfect sphere upon another perfect sphere. In practice, you can't because setting up such an arrangement is practically impossible.
Yes, but we don't actually know that we can build such a device.
In practice you're right, though, usually new funding in one place gets taken from somewhere else. But if the world really wanted scientific progress we could afford to fund some more speculative projects.
Yes, but it is not possible to assert that both are true at the same time with full certainty.