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IBM casts doubt on Google's claims of quantum supremacy

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

#61

Post by theon144 »

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 something that requires a classic computer 10 hours.

0: https://gilkalai.wordpress.com/2019/10/13/the-story-of-poinc... 1: https://news.ycombinator.com/item?id=21334403

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

#62

Post by mantap »

andrewla wrote: post #50

Also of note is Gil Kalai's updated take on the experiment [1]. The heart of the complaint is that the quantum computer's solution to this problem relies on a calibration process, which is done on a classical computer and requires resources orders of magnitudes higher than the quantum portion of the computation: > The Google experiment actually showed that a quantum computer running for 100 seconds PLUS a classic com…

If I understand his point correctly, it's not the calibration per se that is problematic, but whether the calibration means that it only performs for a small subspace of inputs, which raises the question how large is that subspace?

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

#63

Post by K0SM0S »

DashAnimal wrote: post #23
K0SM0S wrote: post #18

Earlier quoted context omitted.

Edit: I am definitely wrong about my interpretation (see child post by DashAnimal) ____ Original comment for reference: I really don't think IBM implied the social (and definitely modern, circumstancial) figurative meaning of supremacy. Any tech geek, or history major for that matter, would just read it as "crushing domination", with a strong implication that others won't be able to catch up, ever. You know, like Kin…

No, they definitely did. In the original blog: > Professor Preskill summarized the two main objections to the term that have arisen from the community by explaining that the “word exacerbates the already overhyped reporting on the status of quantum technology” and that “through its association with white supremacy, evokes a repugnant political stance.” > Both are sensible objections. And we would further add... https…

Oh, my. IBM is way lower than I thought. Thank you for setting my perception straight; I amended GP accordingly.

I would almost qualify that as intellectual self-subjection (and perhaps ethical, in the way of science). Aiming so low that it's trolling, for lack of a better word.

Wikipedia's "Quantum supremacy"[1] article:

> The term was originally popularized by John Preskill[2] but the concept of a quantum computational advantage, specifically for simulating quantum systems, dates back to Yuri Manin's (1980) and Richard Feynman's (1981) proposals of quantum computing.

[1]: https://en.wikipedia.org/wiki/Quantum_supremacy

[2]: https://arxiv.org/abs/1203.5813 (2012, in the abstract: “[...] we hope to hasten the day when well controlled quantum systems can perform tasks surpassing what can be done in the classical world. One way to achieve such "quantum supremacy" would be to run an algorithm on a quantum computer which solves a problem with a super-polynomial speedup relative to classical computers [...]”)

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

#66

Post by zaroth »

andrewla wrote: post #50

Also of note is Gil Kalai's updated take on the experiment [1]. The heart of the complaint is that the quantum computer's solution to this problem relies on a calibration process, which is done on a classical computer and requires resources orders of magnitudes higher than the quantum portion of the computation: > The Google experiment actually showed that a quantum computer running for 100 seconds PLUS a classic com…

Crucial question - is the calibration a one time effort where the same calibration can be used to calculate any number of results within the calibrated space? In other words, can you amortize the calibration cost across 1,000 runs and come out an order of magnitude ahead?

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

#67

Post by AlexCoventry »

htfu wrote: post #56
AlexCoventry wrote: post #39

Earlier quoted context omitted.

For market forces to be meaningful, the calculation would need to provide value to someone. At the moment the desired output is simply "a distribution which is hard to simulate classically," so assessment in terms of market value would be very premature.

But that goes for any raw benchmarking, it’s busywork by design.

I'm pretty cynical about this specific experiment, but that's taking it to another level.

The ROI was terrible, but it wasn't mere busywork when Galileo was mucking around with balls and ramps.

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

#68

Post by AlexCoventry »

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.

My impression is that the difficulty is linear in the depth of the calculation, exponential in the number of qubits.

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

#69

Post by andrewla »

mantap wrote: post #62
andrewla wrote: post #50

Also of note is Gil Kalai's updated take on the experiment [1]. The heart of the complaint is that the quantum computer's solution to this problem relies on a calibration process, which is done on a classical computer and requires resources orders of magnitudes higher than the quantum portion of the computation: > The Google experiment actually showed that a quantum computer running for 100 seconds PLUS a classic com…

If I understand his point correctly, it's not the calibration per se that is problematic, but whether the calibration means that it only performs for a small subspace of inputs, which raises the question how large is that subspace?

My understanding is that the calibration could only be feasibly carried out for smaller circuits where simulating the circuit classically was possible. At issue is whether the calibration is generalizable; whether the calibration carried out for a particular small circuit C was reused to simulate another circuit C', or whether fresh calibrations were carried out.

Page 17 of the supplemental data [1] shows the calibration process in schematic, and appears to indicate that the calibration was necessary for each input circuit C, since the graph showing the fidelity improving with iterations of the calibration is labelled "b, Data from a two-qubit XEB experiment." The water is admittedly muddy, and hopefully clarification will be forthcoming from some quarter to determine whether Kalai's particular critique has substance.

[1] https://static-content.springer.com/esm/art%3A10.1038%2Fs415...

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

#70

Post by andrewla »

zaroth wrote: post #66
andrewla wrote: post #50

Also of note is Gil Kalai's updated take on the experiment [1]. The heart of the complaint is that the quantum computer's solution to this problem relies on a calibration process, which is done on a classical computer and requires resources orders of magnitudes higher than the quantum portion of the computation: > The Google experiment actually showed that a quantum computer running for 100 seconds PLUS a classic com…

Crucial question - is the calibration a one time effort where the same calibration can be used to calculate any number of results within the calibrated space? In other words, can you amortize the calibration cost across 1,000 runs and come out an order of magnitude ahead?

See the comments on Kalai's post from Peter Shor, where Kalai attempts to address this, and my reply to mantap on this thread where I try to give my poor understanding of the critique.
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