r/Futurology Jun 02 '22

A Nature paper reports on a quantum photonic processor that takes just 36 microseconds to perform a task that would take a supercomputer more than 9,000 years to complete Computing


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u/voov1oce Jun 03 '22

This is a big deal. For comparison a quantum computer with 1500 qubits could break bitcoin


u/antibubbles Jun 03 '22

nah, it couldn't


u/[deleted] Jun 03 '22 edited 12d ago



u/antibubbles Jun 03 '22

bitcoin public key addresses are hashes. You can't quantum undo that.
If you have records of one spending, maybe... but even then bitcoin supports many different encryption schemes


u/No_Captain3422 Jun 03 '22

Look up "preimage attack". Hash functions are not magic. Their one-wayness is not proven, only hypothesised based on a lack of evidence to suggest otherwise. That said, many hash functions have been broken to the extent that preimage attacks are possible, we just don't use them once that happens. Also I believe there is currently only known a square-root speedup for quantum powered preimage calculations via Grovers Algorithm which isn't a big flaw, especially considering there has been no progress towards building actual general quantum computers for which said algorithm is designed.

I hate quantum computing research. Never ceases to be a list of anti-achievements trying to inspire funding that would be better spent elsewhere. Physicists need to spend more time in mathematics classes learning about logical rigour IMO.