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Google claims to have proved its supremacy with new quantum computer

telegraph.co.uk

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Re: Google claims to have proved its supremacy with new quantum computer

#141

Post by lbourdages »

refulgentis wrote: post #134
lbourdages wrote: post #49

Earlier quoted context omitted.

The main issue I had with their demonstrations were that the problems they chose were essentially "let's show that a quantum computer is better at being a quantum computer than a classical computer". Obviously they are, just like I'm better at being a human than ChatGPT is. I'm not saying they suck, but to proclaim that "quantum computers are superior" you need an actual use-case, IMO.

It's absolutely non-obvious, I'm dead serious. As far as I've understood keeping up over the years, there's a credible argument from a respected academic in the QC community that quantum computing is impossible.

Do you have a link handy? You've piqued my curiosity!

Re: Google claims to have proved its supremacy with new quantum computer

#142

Post by ImPostingOnHN »

Aperocky wrote: post #28
rcme wrote: post #23

Earlier quoted context omitted.

Did you really get the answer faster than a computer?or put another way, what question did you answer? How much force was applied to the stick before it broke? How fast was the stick moving 0.04s after breakage? How much sound was produced? There are thousands of questions you don’t have answers to when you simply break a stick.

I think that was his exact argument against quantum computing.

seems more like an argument for quantum computing

Re: Google claims to have proved its supremacy with new quantum computer

#143

Post by mabbo »

I feel like quantum computing is one of those technologies that is going to be a lot of hype and excitement by researchers, but no real applications and no real impact to the general public.

... Until the day that it does.

And then, a lot of very interesting things will happen very quickly, and the world will change massively.

Re: Google claims to have proved its supremacy with new quantum computer

#144

Post by refulgentis »

lbourdages wrote: post #141
refulgentis wrote: post #134

Earlier quoted context omitted.

It's absolutely non-obvious, I'm dead serious. As far as I've understood keeping up over the years, there's a credible argument from a respected academic in the QC community that quantum computing is impossible.

Do you have a link handy? You've piqued my curiosity!

Here's an exhaustive covering: https://www.scottaaronson.com/democritus/lec14.html

I would have picked it up in bits and pieces from blogs over years, here's an attempt to render that useful that is surely nitpickable:

TL;DR: there's two types of caring about Google's claims of quantum supremacy:

1. HN tends to assume these articles are about breakthrough in _product usefulness_ and then tsk tsk about lack of impact. c.f. top comment currently gravely noting after reading the paper, its too noisy and a long way off.

2. The papers are about demonstrating _there is quantum computing at all_, the interest in the people in the know is about settling that question, the raw strongman feat isn't particularly interesting.

Re: Google claims to have proved its supremacy with new quantum computer

#145

Post by knorker »

staunton wrote: post #100
knorker wrote: post #9

Earlier quoted context omitted.

My understanding is that quantum computers only have two real use cases, as of today: 1. Breaking crypto. 2. Simulating other quantum systems. For (1) it's basically all downsides. For (2) unless you're a particle phycisist you'll never need quantum computers. But that's now. Maybe there will be a killer app for it some day, changing everything. Or indeed, we could get it indirectly. Maybe simulating quantum systems…

(2) can be very relevant to material science and chemistry. Those things have huge ranges of important practical applications. For example, people currently struggle to do accurate calculations of the band structures of materials and it doesn't look like there will be much progress there using only classical computers (using more computing power or better approximation tricks). Big enough quantum computers could do t…

Indeed. That's what I meant by my example of indirect benefit.

Simulating physical systems better, faster, and more completely, can have many practical applications.

But unless you're already today trying to simulate physical systems like that, then QC probably won't help you one bit.

Re: Google claims to have proved its supremacy with new quantum computer

#146

Post by tsimionescu »

dataflow wrote: post #35
wuubuu wrote: post #24

Earlier quoted context omitted.

Not a dumb question! There is a great video by the mathematician Richard Borcherds on this exact objection to current examples of quantum supremacy. https://www.youtube.com/watch?v=sFhhQRxWTIM

I love this video, thanks for sharing it. I'm watching it right now and I think I'm going to refer to his "teapot supremacy" from now on.

There is also an interesting response to that video from a leading quantum computer scientist, Scott Aaronson:

https://scottaaronson.blog/?p=5460

He actually goes into significant details about your exact question and proposes some resolutions. It's quite long and I don't think I can do it justice in a TLDR so leaving the link to speak for itself.

Re: Google claims to have proved its supremacy with new quantum computer

#147

Post by dataflow »

tsimionescu wrote: post #146
dataflow wrote: post #35

Earlier quoted context omitted.

I love this video, thanks for sharing it. I'm watching it right now and I think I'm going to refer to his "teapot supremacy" from now on.

There is also an interesting response to that video from a leading quantum computer scientist, Scott Aaronson: https://scottaaronson.blog/?p=5460 He actually goes into significant details about your exact question and proposes some resolutions. It's quite long and I don't think I can do it justice in a TLDR so leaving the link to speak for itself.

Thanks for the link! I'll take a look.

Edit: I just read it and I don't feel like he really answered the question. He had a rebuttal about being able to freely specify parameters, but then his Facebook friend addressed his rebuttal, to which he replies "this is indeed more interesting"... which, well, it certainly is, and also doesn't answer the question!

(Well, I guess he also mentions we should expect speedup greater than Avogadro's number, which seems fair, but clearly that's not the bar anyone is claiming to meet, so it doesn't get us anywhere.)

Re: Google claims to have proved its supremacy with new quantum computer

#148

Post by knorker »

pyrale wrote: post #106
knorker wrote: post #9

Earlier quoted context omitted.

My understanding is that quantum computers only have two real use cases, as of today: 1. Breaking crypto. 2. Simulating other quantum systems. For (1) it's basically all downsides. For (2) unless you're a particle phycisist you'll never need quantum computers. But that's now. Maybe there will be a killer app for it some day, changing everything. Or indeed, we could get it indirectly. Maybe simulating quantum systems…

Basically, quantum computers can solve problems of the BQP class in a time that is a polynomial function of input size. These same problems, on a traditional computer, can take exponential time. It is hard to tell with certainty what can be done with quantum computers, but having powerful quantum computers will certainly open new fields of research, like trying to figure out if quantum algorithms for NP-class problem…

This is so extremely well put that I want to reply just to highlight it.

What you said was the optimist view, that there's a world of possibilities. It's just that at the moment we just have the two I mentioned.

Maybe there's much more, and if we build it (the hardware), they (the algorithms) will come.

But for now really just the two. AFAIK.

Re: Google claims to have proved its supremacy with new quantum computer

#149

Post by fnordpiglet »

ithkuil wrote: post #133
fnordpiglet wrote: post #122

Earlier quoted context omitted.

I don’t think you guys are tackling this right. You can observe the stick breaking to absurd precision, even using an electron tunneling microscope, and produce immense amounts of data about the sticks state at every point in the breaking and afterwards faster than a computer can simulate breaking the stick. The key is the stick breaking and it’s observation at any level of detail happens in parallel with all aspects…

But the comparison is not fair. Yes the electron microscope can image a lot of details "in parallel" but not all details from all angles, all internal microfractures. You can't easily measure all temperature gradients in all cubic nanometers of the material etc etc. The simulation is slow because it works at that level and thus as a side effect will also give you that output. Obviously if you don't need all that info…

You could though, it’s entirely fair. All information about the system is available for measurement down to the quantum level across all dimensions, because it’s a perfect fidelity to reality. Regardless of whatever specific tool you choose, in theory I could build tools that measure in near infinite detail the stick. I could not however build a computer that could calculate that detail of the stick with perfect fidelity to reality. It’s a gross approximation no matter what you do. I would however point out that my nbody example is entirely analogous and is perhaps more tractable as to why it’s impossible to compare measuring reality to calculating a simulation. Simulations have the advantage that you can reproduce and tweak it repeatedly without having to configure the universe in a specific way every time. You can hold variables constant, you can change the laws of nature, you can simplify complexities to narrow in on a specific behavior. But simulations are never a replacement for measurement of reality, and the reason is the opposite of what you’re holding out. Reality can be measured to an arbitrary level of complexity literally in real time, even systems that are so complex we can’t consider possibly simulating even approximations of the system.
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