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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

#111

Post by aleksiy123 »

dataflow wrote: post #7

Dumb question: Say I have a wooden stick and I break it in half in less than a second. Assume a computer would need several minutes to simulate everything that would've happened in the stick. I clearly got the output faster than a computer (and with more precision), so does this imply I'm doing anything particularly fascinating? I assume the same scenario is possible to concoct for a quantum computer. I assume it wou…

If you need to measure a billion sticks breaking the simulation might start to come out ahead in terms of cost.

I think this makes more sense if you use a bridge instead of a stick.

Building a full sized bridge to test your idea is prohibitively expensive but a simulation is cheaper to build even if the actually simulation is slower to compute.

In real life simulations, small prototypes , and full size prototypes are all useful with various trade-offs of cost and benefits at various stages.

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

#112

Post by klyrs »

sporkl wrote: post #48

I don't remember the details, but the reason the 2019 paper was challenged was because Google did not take into account quantum simulation optimization techniques when estimating how long the computation would run on classical computers. I wouldn't be surprised if there's a similar situation here, where unconsidered optimizations prevent this from being quantum advantage.

As I recall, they did not take the error rate into account. The result was dashed by somebody looking at their error rate and saying "we can compute that distribution to within 5%* with a classical computer." One would hope that they learned from this, but historically, supremacy claims have been rather short-lived.

* number pulled out of a hat

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

#114

Post by EGreg »

squarefoot wrote: post #113

I know nothing about quantum computing, but when I read "does X instantly when rivals need 47 years", I immediately think about it being abused for brute forcing passwords and encryption keys. Would it be possible?

Why are you being downvotdx? We need to have way more discussion about this. The answer is — no one knows. In fact even classical computer algos might soon break modern crypto, especially Elliptic Curve crypto.

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

#115

Post by Arch485 »

squarefoot wrote: post #113

I know nothing about quantum computing, but when I read "does X instantly when rivals need 47 years", I immediately think about it being abused for brute forcing passwords and encryption keys. Would it be possible?

Not yet!

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

#116

Post by dataflow »

kelnos wrote: post #110
dataflow wrote: post #79

Earlier quoted context omitted.

> The best way to get a fast intuition for why the simulation is superior is to take an entry-level CAD course with a focus on material design. I'm sorry but you're completely missing the point of my question. The question was not "what can simulations do that experiments can't". My background in simulation is not zero, and I've never had that question. The question as something else entirely. > You can’t measure a n…

> What if all I care about is something easily measurable, like the length of each remaining piece? If you're not just talking about the two large pieces, but also the lengths of the small splintered pieces, I suspect the computer is going to be a lot faster at figuring that out than you will be manually measuring them. Your responses in this thread seem to be a bit disingenuous: first you ask why a computer simulati…

> first you ask why a computer simulation could be better than doing it manually

No, I never asked this at all. Some people changed the question to this for reasons I still don't understand. The actual question I asked was: "what are the criteria for distinguishing those scenarios from the interesting cases? And how do we know which case this one is like?"

The whole point here is to figure out if the problems they're declaring computational superiority on are analogous to the wooden stick problem here. Not to ask "when are simulations better than doing it manually".

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

#117

Post by alpineidyll3 »

abdullahkhalids wrote: post #101
alpineidyll3 wrote: post #94

Earlier quoted context omitted.

Yes, but all existing photonic platforms use post-selection which is even more clearly exponentially lossy. Although this could be solved with a deterministic single photo source if one can be found. Photonic quantum computing is an especially funny post-transistor paradigm because classical photonic computing is also quite attractive.

If you read the linked article, it explains how to avoid exponential loss on post-selection. > Imagine you can toss coins, and you need to generate 20 coins showing Heads. If you repeatedly toss all 20 coins simultaneously until they all come up heads you’d typically have to do so millions of times before you succeed. This is even more true if each coin also has a 20% chance of rolling off the table (akin to photon l…

Haha a self promotional blog post without any experimental data from a lab self-interested in the technology is somehow not persuasive to me.

There is no way to add entangled particles to an entangled photon state without new light matter interaction which may (and almost certainly) bring decoherence.

Ie to claim a good enough switch is possible is a claim demanding a ton of evidence, and there is none right now.

Ofc I would be thrilled to see it work! But explaining a scheme in back of the envelope fashion and measuring it are two vastly diff things.

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

#118

Post by pieter_mj »

AlexCoventry wrote: post #82
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.

I declare AlexCoventry supremacy. No one can compute AlexCoventry better than I can. :-)

Wait until you see a GTP5 simulation of yourself.

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

#119

Post by rvz »

DonHopkins wrote: post #41
jl6 wrote: post #31

The ability to entangle particles feels like a really amazing new capability. (New in the last 100 years anyway). Like it’s a brand new kind of substance that has never been made before. Everything in all of history has been built out of boring old atoms, not these fancy new entangled things. Even if quantum computers turn out not to be able to solve interesting problems, I wonder if computers are the only thing we c…

Electric space heaters? That's crypto's most practical application.

Nope.

That is now overtaken by AI (Especially LLMs), [0] which does not have any efficient methods of training, fine-tuning and inferencing.

Crypto on the other hand has already has alternative consensus algorithms available today which can cut it emissions down significantly [1].

[0] https://gizmodo.com/chatgpt-ai-water-185000-gallons-training...

[1] https://consensys.net/blog/press-release/ethereum-blockchain...

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

#120

Post by alpineidyll3 »

s1dev wrote: post #102
alpineidyll3 wrote: post #75

Earlier quoted context omitted.

Note: that there is good physical reasons why the cost of QC may grow exponentially with qbits. Refrigeration is exponentially inefficient as T=>0 and the gap of a quantum system which sets the temperature you must cool to shrinks as you couple new degrees of freedom. This dynamic has been the basic reason for the sub exponential progress in the area (despite exponential expenditure)

This is not quite true. You only need to keep the qubits at a fixed temperature as you scale the system, so the resources required to add additional qubits grow only polynomially with the system size. Once you have many qubits with a sufficiently low (but constant) error rate, you can do quantum error correction which also only has polynomial overhead.

No you are missing the fact that if the qubits are coupled the systems fundamental gap has shrunk demanding a lower temperature for the same error rate.

You should think more about why your rosy scheme hasn't worked yet if you can't explain that empirically maybe you don't quite understand.

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