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Comment by bvod | Hacker News Reader

I tried testing the Bernstein Vazarani algorithm on a 5 qubit quantum computer that IBM let us use for an afternoon for one of my university classes last semester. It was unable to recover the hidden string, even though simulating the circuit classically recovered it. Anyone can launch a "quantum computer as a service" platform, but the service won't be valuable if the computer doesn't work. And so far no quantum computer has solved a problem faster than we can do classically

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> but the service won't be valuable if the computer doesn't work.

So the state-of-the-art in quantum computing is still basically "can tell you the 200th prime number, sometimes"?

Not very useful.

Even if this is the case, at first people were scratching their head looking at the transistor what it might be good for.

No, the transistor replaced the vacuum tube, which everyone was already using. When the transistor was invented everyone rushed to use it because it was clear what it was good for.

No, first customer of the transistor was the government because they were the only ones who could afford it.

Yes, and the reason the government rushed to it is because they wanted the absolute best technology (that was orders of magnitude better than anything else) and would pay for it to have a leg up over their enemies. If they were cheap right when they came out, everyone would have bought them.

My point is that QC-s have the potential to be as revolitonary as transistors were. Yet we are at the level when transistors were mostly used to make radios portable. Thus it's not really justified to mock them as lame factoring devices.

That's not how I read your comment. It clearly tries to suggest that when the transistor was first invented people did not know what to do with it.

I think the MASER/LASER would have been a far better example.

I read that somewhere (can't recall the source) that it was a nice gadget, but it wasn't an overnight sensation. You are right, MASER/LASER is a better analogy.

If you are talking about transistors, when they were invented the only other alternatives were triodes (vacuum tubes) or mechanical relays. Both were orders of magnitude less reliable and slower in terms of switching speed. When transistors were invented it was a mad dash to get them cheap and small enough to replace everything else, because everyone could tell they were the future. It took 9 years between the first transistor and receiving the Nobel Prize for it.

I don't know where you read that but that is not the story that I'm familiar with.

Applications for the transistor were known before the device even existed.

The problems were first to make them reliably, then to make them in quantity and finally to make them cheap enough. All those were overcome and the revolution that followed has not stopped even today.

Perhaps a Leyden jar, or Aeolipyle. Novelties with great potential. Or perhaps, they're just a drinking bird kind of novelty - i don't think so, but maybe. QM is rock solid, but it doesn't tie together well with our other theories about the world. Maybe knowing more will make the error correction easier somehow.

I kinda think we're in the difference engine phase of quantum computing. Same problems as Babbage building a neat thing, but we're missing some details and our tools aren't really sharp enough to make a good one.

But this is new territory, and researchers shouldn't give up just because it doesn't work very well now.

I recall that the iPhone/iPad were preceded by attempts at tablet computing that were very crude in comparison.

Give it a couple of years and see where it leads.

> I recall that the iPhone/iPad were preceded by attempts at tablet computing that were very crude in comparison.

That's a very poor analogy. Here we are talking about stuff that is not even functional, technology wise.

Poor poor analogy, but at least you get the picture.

They are talking 15- and 17-qubit-capable processors today, but are looking at 50-qubit ones in a few years.

The key question is whether QC algorithms are scaling as predicted by QC theory, or at least better than classical algorithms for the same task. If the error correction is causing them to scale poorly, the design is probably infeasible for large-qubit calculations.

I expect it is scaling poorly, or IBM would have reported otherwise when moving from 5- to 16-qubit machines.

The current state of the art in QC is more like Alan Kay's Dynabook paper: https://en.wikipedia.org/wiki/Dynabook

i.e. even the "very crude attempts" stage (your Newtons or Palm Pilots) is still science fiction.

That sounds right, but also like an argument against commercial availability just yet in my ears.

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