Guys. Stop. This piece is from "Nature: Futures", which it makes clear at the top of the page. Futures is
fiction. The whole purpose of it is for scientists and science journalists to submit
fictional articles that they could imagine might be written in the future.
Look at what Nature says about Futures here (emphasis mine):
Futures is the award-winning science-fiction section of Nature and it accepts unsolicited articles. Each Futures piece should be an entirely fictional, self-contained story of around 850–950 words in length, and the genre should, broadly speaking, be 'hard' (that is, ‘scientific') SF rather than, say, outright fantasy, slipstream or horror.
And here:
Futures is a venue for very short stories or ‘vignettes’ of between 850 and 950 words. The subject is typically near-future, hard SF, although this can be interpreted liberally.
OP is a known troll and is baiting you all in to thinking this is real. It is fiction. No, bitcoin has not just been broken by quantum computers.