[gpm]

I put the word "some" in front of "crypto" for a reason.

There is some crypto that we know how to break with a sufficiently large quantum computer [0]. There is some we don't know how to do that to. I might be behind the state of the art here, but when I wasn't we specifically really only knew how to use it to break cryptography that Shor's algorithm breaks.

[0] https://quantum-journal.org/papers/q-2021-04-15-433/

[dwnw]

Nope. Any crypto you can break with a real, physical, non-imaginary quantum computer, you can break faster with classical. Get over it. Shor's don't run yet and probably never will.

You are misdirecting and you know it. I don't even need to discredit that paper. Other people have done it for me already.

[rhubarbtree]

This is incorrect. Whilst you may be sceptical about whether quantum computers can be realised, the theoretical result is sound.

Recent advances in quantum error correction are a significant increase in confidence that quantum computers are practical.

We can argue about timelines. I suspect it is too early for startups to be raising funds for quantum computers at this stage.

Source: I worked in quantum computing research.