Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

IBM casts doubt on Google's claims of quantum supremacy

ibm.com

Post reply on HN
Print view View original

141–149 of 149 posts

Re: IBM casts doubt on Google's claims of quantum supremacy

#141

Post by scottlegrand2 »

sanxiyn wrote: post #102
knzhou wrote: post #99

Following the quantum supremacy controversy is very frustrating. It gets constantly framed as a decisive step that changes everything, which is wrong. But then there's also an opposite and equally wrong reaction that any challenges to the claim prove that quantum computing doesn't work at all. The reality is that quantum computing technology has been improving at the same steady pace for decades, and quantum supremac…

Quantum supremacy is a big deal. It is a goddamn experimental evidence against Extended Church-Turing Thesis. If you never believed ECT (for example, all physicists seem to think ECT is obviously false) it may not matter to you, but it still is a serious claim. Yes, Google probably can achieve quantum supremacy by slapping a few more qubits. But a few more qubits were, in fact, not slapped yet. So quantum supremacy i…

I think the problem is that perfectly wonderful science has been put in the hands of marketing people. And those are the same marketing people that kept telling us L5 autonomy was right around the corner. Or more lately that we couldn't discount the possibility of a near-term AGI. Great science, lousy PR IMO.

Re: IBM casts doubt on Google's claims of quantum supremacy

#142

Post by webkike »

wongarsu wrote: post #122
webkike wrote: post #114

Earlier quoted context omitted.

No, the bound is not on the performance of the sorting algorithm, but rather on the minimum number of comparisons required

I would argue that "number of comparisons" is just the popular performance metric. Of course in reality we care about execution time, and in order to go from "we need O(n * log(n)) comparisons" to "we need O(n * log(n)) time" you need additional assumptions, like "memory access takes O(1) time, and the speed of one comparison is independent of the total amount of data". But for any reasonable set of assumptions an al…

I disagree, because it is perfectly possible to sort without comparisons. For example, sorting a list of distinct integers is theoretically O(N). (radix sorting)

Re: IBM casts doubt on Google's claims of quantum supremacy

#143

Post by [deleted] »

lallysingh wrote: post #35
AlexCoventry wrote: post #33

Earlier quoted context omitted.

So if they increase the number number of qubits they'll be have a classically infeasible calculation again? Should be interesting.

If the problem is linear, then frankly I don't think anyone cares if there's a QC implementation.

[deleted]

Re: IBM casts doubt on Google's claims of quantum supremacy

#144

Post by jeremysalwen »

webkike wrote: post #142
wongarsu wrote: post #122

Earlier quoted context omitted.

I would argue that "number of comparisons" is just the popular performance metric. Of course in reality we care about execution time, and in order to go from "we need O(n * log(n)) comparisons" to "we need O(n * log(n)) time" you need additional assumptions, like "memory access takes O(1) time, and the speed of one comparison is independent of the total amount of data". But for any reasonable set of assumptions an al…

I disagree, because it is perfectly possible to sort without comparisons. For example, sorting a list of distinct integers is theoretically O(N). (radix sorting)

That's not sorting, that's sorting distinct integers, which is a different problem.

That's like saying multiplication can't have any lower bound because multiplying by zero is O(1).

Re: IBM casts doubt on Google's claims of quantum supremacy

#145

Post by Veedrac »

theon144 wrote: post #61
unnouinceput wrote: post #53

Quote 1: "The Google group reiterates its claim that, in 200 seconds...." Quote 2: " ...by tweaking the way Summit approaches the task, it can do it far faster: in 2.5 days." Well, it's still 200 seconds vs 2.5 days, so I'd say the claim kinda stands. I know I would definitely buy the computer with 200 seconds vs the one with 2.5 days.

Not sure it's that clear cut, as per the blog post[0] linked elsewhere in this thread[1]: > Recall that a quantum supremacy demonstration would be an experiment where a quantum computer can compute in 100 seconds something that requires a classical computer 10 hours. (Say.) >The Google experiment actually showed that a quantum computer running for 100 seconds PLUS a classic computer that runs 1000 hours can compute s…

According to Scott Aaronson this claim is incorrect.

> Next he said that the experiment is invalid because the qubits have to be calibrated in a way that depends on the specific circuit to be applied. Except, this too turns out to be false: John Martinis explicitly confirmed for me that once the qubits are calibrated, you can run any circuit on them that you want.

Re: IBM casts doubt on Google's claims of quantum supremacy

#146

Post by mellosouls »

mannykannot wrote: post #133
mellosouls wrote: post #94

Earlier quoted context omitted.

Thanks no worries

I stand corrected by Scott Aaronson! [1] One of the things he says is that it would be useful to run IBM's algorithm, not to show that it can be done, but to verify Google's 53-qubit and depth-20 result, as, so far, Google has only been able to present indirect evidence that they are getting the correct result at this size of problem. [1] https://www.scottaaronson.com/blog/?p=4372

Yes, thanks, I've since read that - excellent and thorough article.

Re: IBM casts doubt on Google's claims of quantum supremacy

#147

Post by a_imho »

jaredtn wrote: post #107

Summary: - Google overhyped their results against a weak baseline. This seems to be commonplace in academic publishing, especially new-ish fields where benchmarks aren't well-established. There was a similar backlash against OpenAI's robot hand, where they used simulation for the physical robotic movements and used a well-known algorithm for the actual Rubik's Cube solving. I still think it's an impressive step forwa…

Also AlphaZero vs Stockfish, the setup has/had a big question mark over it as well.

Re: IBM casts doubt on Google's claims of quantum supremacy

#148

Post by CJefferson »

tarsinge wrote: post #135
CJefferson wrote: post #19

This had been a consistent problem with quantum computers - - they come up with a quantum computer that can basically do one thing and compare it against a general piece of software not tuned for that problem. Once the software is tuned for the exact problem it is much closer in performance to the quantum computer. The same thing arises with dwave.

Yes « Tuned » with 250 Petabytes of storage

To be fair, that exact computer is, I believe, what Google originally composted against.

Re: IBM casts doubt on Google's claims of quantum supremacy

#149

Post by webkike »

jeremysalwen wrote: post #144
webkike wrote: post #142

Earlier quoted context omitted.

I disagree, because it is perfectly possible to sort without comparisons. For example, sorting a list of distinct integers is theoretically O(N). (radix sorting)

That's not sorting, that's sorting distinct integers, which is a different problem. That's like saying multiplication can't have any lower bound because multiplying by zero is O(1).

That's not a definition supported by any literature I've read. Seems like you're moving the goalpost because you don't like the definition. For what it's worth, radix sort is listed on the wikipedia page for "Sorting Algorithms", and its runtime is listed as O(n * k) where k is the number of digits per number: https://en.wikipedia.org/wiki/Sorting_algorithm#Radix_sort
Post reply on HN