Comment by hannob | Hacker News Reader

Comment by hannob | Hacker News Reader

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> With regards to the D-Wave systems in particular, are these actually faster than solving the problems with a classical approach?

Obviously the answer to that is "No".

Google just did a "Quantum supremacy" experiment with lots of fanfare and some criticism that it really wasn't (details on that are complex). Quantum supremacy is exactly the thing you're asking for: Can we do something, anything at all, with a QC that we couldn't just do on average computers?

The important thing to realize is: Google did this with a very specific problem that was suitable for their quantum computer. It wasn't something that was practically useful. They chose a problem they could solve, nothing more. Noone has claimed to have run a quantum supremacy experiment on D-Wave.

My best guess is all their happy customers had a problem that needed to be solved, they solved it, and nobody asked if the "quantum" aspect was particularly relevant in it.

An important point about the technical meaning of "quantum supremacy": It is only the claim that a problem exists that can be solved on existing quantum computers and not on existing classical computers. The problem that Google used to demonstrate quantum supremacy has no practical uses, and no useful problem is known that can act as a witness for quantum supremacy. The practical implication: "Getting you problem solved" cannot be the motivation for buying quantum compute power from D-wave (unless you have no clue). Possible valid motations: "learning to work with quantum computers", "seeming cool", "donating money to companies that may build useful quantum computers in the future".

I thought the problem had some limited applications. Wasn't it something like modeling the quantum states of hydrogen?

That was a different test, that wasn’t trying to do something infeasible classically. The supremacy test was effectively solving a contrived combinatorics problem.

Thanks for the link, based on the reading I think I was walking whether there was a quantum advantage and it’s magnitude, although the quantum supremacy aspect is interesting too.

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