Google claims to have proved its supremacy with new quantum computer • Hacker News Board

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

#181

Post by gaze » Tue, Jul 04, 2023, 12:48 AM UTC

marricks wrote: post #10

> He said: “This is a very nice demonstration of quantum advantage. While a great achievement academically, the algorithm used does not really have real world practical applications, though. > “We really must get to utility quantum computing – an era where quantum computers with many thousand qubits actually begin to deliver value to society in a way that classical computers never will be able to.” This seems to be t…

The field of quantum computing HAS to have incremental results, or else nobody will continue to fund it. Unfortunately, it doesn't seem to be presenting great opportunities for incremental results. This doesn't invalidate the field, it just means that it's really hard to tell if you're going to see a pay-off. These things aren't really factored into the risks that investors think they're taking, so it's giving me a weird feeling in the pit of my stomach. I desperately want to see quantum computing work -- I've worked on it for 15 years now. From my vantage point, I see progress, but that's progress in making better qubits, better gates, better architectures, not solving problems. There's an error correction threshold, remember, and you start seeing real results when/if you cross it.

Anyhow, with all these huge beautiful dilution fridges with their fancy gold plating and all that, the expense of QC is a rounding error relative to AI. It's still high-risk/high-reward and has seen a level of investment that's commensurate with that.

Also, I don't know who all thinks that these physicists like myself are making beaucoup bucks working on QC. I make far less than a software engineer at grubhub or something, and have taken the opportunity cost of getting a PhD and all that.

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

#182

Post by [deleted] » Tue, Jul 04, 2023, 12:52 AM UTC

alpineidyll3 wrote: post #75

AbrahamParangi wrote: post #58

Earlier quoted context omitted.

There's a fundamental question as to whether or not it's exponentially difficult to add additional qubits. If each marginal qubit is 5% more difficult to add as the previous one the task would be essentially impossible - and even if it wasn't impossible it would turn out to basically be cheating (in that you would be doing exponential work via either the quantum computing route or the conventional route).

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)

[deleted]

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

#183

Post by ori_b » Tue, Jul 04, 2023, 12:58 AM UTC

__MatrixMan__ wrote: post #152

ori_b wrote: post #98

Earlier quoted context omitted.

Does Google's implementation of quantum computing help with this sort of scenario, or is it a really fancy way of breaking the bridge?

Well you don't have to sacrifice any sticks or bridges to see what happens, so that's a plus. One could imagine stimulating experiments that are implausible to actually perform.

Yes, but that's nothing new -- we've had computers that were used to solve simulations faster than digital comuters could by setting up electronic (or hydraulic, or pneumatic) parts that simulated the terms of the differential equations: https://en.wikipedia.org/wiki/Analog_computer

Is this quantum computer another iteration on the same concept, or is it solving things that are polynomially harder to simulate classically?

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

#184

Post by hiddencost » Tue, Jul 04, 2023, 1:13 AM UTC

lbourdages wrote: post #49

fsh wrote: post #5

Google's and IBM's previous "quantum supremacy" demonstrations were quickly crushed by improved classical simulations. Let's see if it survives this time.

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.

They're not claiming quantum computers are superior.

They're claiming they have a device which can do something that you couldn't do with a classical computer. A very narrow claim.

It is a big deal to academics, and a number of people here are close to that world and interested.

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

#185

Post by gaze » Tue, Jul 04, 2023, 1:20 AM UTC

alpineidyll3 wrote: post #120

s1dev wrote: post #102

Earlier quoted context omitted.

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.

The qubits aren't all coupled all the time. The whole point of a 2-qubit gate is the coupling is controllable. Also -- why is the gap of the bare system important? The whole point of QEC is the creation of a decoherence free subspace. Your model is wrong and you don't understand quantum error correction.

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

#186

Post by bawolff » Tue, Jul 04, 2023, 1:22 AM UTC

pclmulqdq wrote: post #180

dekhn wrote: post #153

the best thing about watching the entire quantum computing debacle is every time somebody says their QC does something faster than a classical computer, somebody tunes the classical computer to beat the QC. Combined with the fact that chip infrastructure is already paid for and there is a large market to enable economy of scale, coupled with the lack of true problems where exponentially better problem solving is crit…

With all of the sensationalization, I am now convinced that many of the people in quantum computing itself are grifters, and that funding agencies keep paying them to put pressure on classical computing (despite knowing that QC is a big grift). Already, optimization problems have seen classical "ising" chips get great results (as good as the quantum annealing chips), proving that optimization doesn't actually need tu…

When people are hyping something that is probably still 20 years out, i think its safe to say they are trying to sell you something.

Quantum computers will be a real (albeit not earth shattering) advance, but we are still far off.

Still rather people pump money here than crypto bs.

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

#187

Post by bawolff » Tue, Jul 04, 2023, 1:25 AM UTC

erikaww wrote: post #177

deepburner wrote: post #137

Quantum Computing/Information researcher here. This article is largely garbage, the original (~2 month old) paper is surprisingly readable [0] and I suggest you to check it out. Here's my $0.02: The efforts of the Google team is commendable in that they're trying to squeeze as much out of their noisy systems as possible until error correction is here (they need to, to justify their existence after all) and they are a…

I'm not educated on QC. But wouldn't Grover's algorithm be very useful? I believe it provides a sqrt(n) time search. For QC to be useful,it just needs to make common utilities very fast. I should look more into QC. It would be cool if it could speed all computation up. I understand there are algorithms that it could execute that a classical composer could not, but I wonder if it could eventually he like just faster h…

I think you have to scale very big before that starts to matter.

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

#188

Post by pclmulqdq » Tue, Jul 04, 2023, 1:28 AM UTC

bawolff wrote: post #186

pclmulqdq wrote: post #180

Earlier quoted context omitted.

With all of the sensationalization, I am now convinced that many of the people in quantum computing itself are grifters, and that funding agencies keep paying them to put pressure on classical computing (despite knowing that QC is a big grift). Already, optimization problems have seen classical "ising" chips get great results (as good as the quantum annealing chips), proving that optimization doesn't actually need tu…

When people are hyping something that is probably still 20 years out, i think its safe to say they are trying to sell you something. Quantum computers will be a real (albeit not earth shattering) advance, but we are still far off. Still rather people pump money here than crypto bs.

Quantum computing has been 10 years away for the last 30 years.

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

#189

Post by fsh » Tue, Jul 04, 2023, 1:37 AM UTC

erikaww wrote: post #177

deepburner wrote: post #137

Quantum Computing/Information researcher here. This article is largely garbage, the original (~2 month old) paper is surprisingly readable [0] and I suggest you to check it out. Here's my $0.02: The efforts of the Google team is commendable in that they're trying to squeeze as much out of their noisy systems as possible until error correction is here (they need to, to justify their existence after all) and they are a…

I'm not educated on QC. But wouldn't Grover's algorithm be very useful? I believe it provides a sqrt(n) time search. For QC to be useful,it just needs to make common utilities very fast. I should look more into QC. It would be cool if it could speed all computation up. I understand there are algorithms that it could execute that a classical composer could not, but I wonder if it could eventually he like just faster h…

According to a recent article [1], quadratic quantum speedups are very unlikely to outperform classical computers in any application. This is assuming very optimistic parameters for future quantum computers. Grover's algorithm is therefore not considered useful in practice.

[1] https://doi.org/10.1145/3571725

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

#190

Post by fsh » Tue, Jul 04, 2023, 1:40 AM UTC

imchillyb wrote: post #165

deepburner wrote: post #137

Quantum Computing/Information researcher here. This article is largely garbage, the original (~2 month old) paper is surprisingly readable [0] and I suggest you to check it out. Here's my $0.02: The efforts of the Google team is commendable in that they're trying to squeeze as much out of their noisy systems as possible until error correction is here (they need to, to justify their existence after all) and they are a…

> I don't see anything useful coming out until error correction and number of qubits are improved many orders of magnitude to have fault tolerant QC. Error correction and control are vital for any system to be reliable. Thankfully the ability to run simultaneously and vet against multiple outputs should overcome this fault for a time.

This doesn't work because the success probability drops exponentially in the length of the algorithm. It is possible that any real application requires quantum error correction which has not been demonstrated in any meaningful way.