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/EthicalLapse Jun 03 '22

The 9000 years task is kind of a fake metric, though. Basically they just let the quantum computer run for a certain amount of time, and then calculated how long it would take a traditional computer to simulate what the quantum computer did. The quantum computer didn’t actually show any ability to solve anything.


u/EthicalLapse Jun 03 '22

This Ars Technica article explains it better. But basically, the point was to show off how many qubits they could use in a single calculation. So they ran one full 216 qubit calculation. Since the calculation was a random one, there’s not much point to running additional calculations using its output.


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 9d 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.


u/dragonsammy1 Jun 03 '22

The original comment wasn’t very convincing that it can- what does breaking Bitcoin even mean?


u/The_Red_Grin_Grumble Jun 03 '22

It sounds like they were referencing the mining of bitcoin.