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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

#131

Post by knzhou »

jgmatpdx wrote: post #130
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…

> Just by adding a few more qubits IBM's algorithm scales approximately linearly in the number of qubits. So, you'd need more than a few more qubits...

No, in order to get linear time, they used an algorithm which requires exponential space. Once you add a few more qubits that breaks down too.

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

#132

Post by [deleted] »

knzhou wrote: post #131
jgmatpdx wrote: post #130

Earlier quoted context omitted.

> Just by adding a few more qubits IBM's algorithm scales approximately linearly in the number of qubits. So, you'd need more than a few more qubits...

No, in order to get linear time, they used an algorithm which requires exponential space. Once you add a few more qubits that breaks down too.

[deleted]

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

#133

Post by mannykannot »

mellosouls wrote: post #94
mannykannot wrote: post #90

Earlier quoted context omitted.

My apologies for the tone. I should have said that the best route to understanding the issue is probably via the linked post - it worked for me.

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

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

#134

Post by nuncanada »

jgmatpdx wrote: post #130
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…

> Just by adding a few more qubits IBM's algorithm scales approximately linearly in the number of qubits. So, you'd need more than a few more qubits...

No. It scales linearly with circuit size. Exponentially with qubits size. Just read Scott Aaronson's blog, probably the greatest expert on this subject. https://www.scottaaronson.com/blog/?p=4372

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

#135

Post by tarsinge »

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

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

#136

Post by thesz »

rahuldottech wrote: post #111
c3534l wrote: post #105

I don't trust anything IBM says. They have a long history of lying and misleading that continues to this day. It's about as trustworthy as Facebook saying you shouldn't be concerned about privacy on Facebook.

Do you have any sources that elaborate on your claims of IBM being misleading?

https://pdfs.semanticscholar.org/9725/c12506f1d77a3e3b1587cd...

Quotes: "Fear, uncertainty and doubt (FUD) is a tactic used in sales, marketing, public relations,[1][2] politics and propaganda." and "FUD was first defined (circa 1975) by Gene Amdahl after he left IBM to found his own company, Amdahl Corp.:"FUD is the fear, uncertainty, and doubt that IBM sales people instill in the minds of potential customers who might be considering Amdahl products.""

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

#137

Post by tomelders »

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…

It sounds like Quantum Supremacy is the Turing Test of our time. A worthwhile milestone to aim for, but not the holy grail people thought it was.

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

#138

Post by nickpsecurity »

sanxiyn wrote: post #91
nickpsecurity wrote: post #72

I’m with them. My two problems when reading the original argument: They rigged the benchmark to be something quantum-specific before saying classical computers couldn’t do it. I get why. I’d just rather it be something they both could do, classical having great algorithms, and quantum one outperforms it many-fold. An old example was factoring. I’m sure there’s other examples out there. Maybe try to simplify them for…

Your biggest gripe can't be solved. P vs PSPACE is a great unsolved problem in computer science (almost as big as P vs NP), and since PSPACE can simulate quantum computer, any solution to your gripe immediately leads to resolution of P vs PSPACE.

That's disproven or just side-stepped given there's already a solution addressing my biggest gripe: factoring. It's been researched and optimized to death on classical computers. Quantum should get a massive speedup. Such a demo of quantum supremacy would be quite convincing even if not 100% proven.

The QC's aren't big enough for that yet. Surely there are other problems ultra-optimized for classical computers, lots of effort at improving them, and might still have a QC algorithm that beats it by QS-supporting speed-up. Something that fits in these smaller machines. Again, the claim that QC did what CC "likely couldn't" would be validated by the effort CC researchers put into doing it without same results.

I doubt their setup had nearly as many person years of R&D thrown at solving it as factoring, sorting, strings, BLAS, certain assembly routines, optimization techniques, etc. There's probably something in those with an effective alternative that's QC-able.

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

#139

Post by ngold »

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…

Since I had to look it up on Wikipedia.

Quantum supremacy is the potential ability of quantum computing devices to solve problems that classical computers practically cannot. The weaker term Quantum advantage refers to the potential to solve problems faster. In computational-complexity-theoretic terms, this generally means providing a superpolynomial speedup over the best known or possible classical algorithm. The term was originally popularized by John Preskill but the concept of a quantum computational advantage, specifically for simulating quantum systems, dates back to Yuri Manin's and Richard Feynman's proposals of quantum computing.

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

#140

Post by JohnJamesRambo »

Deukhoofd wrote: post #27
JohnJamesRambo wrote: post #20

Earlier quoted context omitted.

Well the word creeps me out and I wish they would choose another. It isn’t even the right word to use since the intended meaning is a quantum computer that can do something that a classic computer can’t do at all, not just better at it. Quantum Possible sounds better to me.

"It isn’t even the right word to use since the intended meaning is a quantum computer that can do something that a classic computer can’t do at all, not just better at it." No, that's exactly what it means in Googles research. It means it can do it faster than a classical computer, not that it's impossible for a classical computer to do.

https://en.wikipedia.org/wiki/Quantum_supremacy

First line- "Quantum supremacy is the potential ability of quantum computing devices to solve problems that classical computers practically cannot."

We can argue about what practically means but I read that as a very very long time. No one worries about someone breaking RSA-2048 with a classical computer because it is "practically" impossible.

>In putting together our video, we estimated the age of the Universe to be 13,751,783,021 years or a little over 13.75 billion years*, therefore if you tried to break a DigiCert 2048-bit SSL certificate using a standard modern desktop computer, and you started at the beginning of time, you would have expended 13 billion years of processing by the time you got back to today, and you would still have to repeat that entire process 468,481 times one after the other into our far far distant future before there was a good probability of breaking the certificate. In fact the Universe itself would grow dark before you even got close.

https://www.digicert.com/TimeTravel/math.htm

This may not be the case with Quantum Possible computation.

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