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Quantum computers: amazing progress, but probably false supremacy claims

gilkalai.wordpress.com

11–20 of 76 posts

Re: Quantum computers: amazing progress, but probably false supremacy claims

#11
My level of expertise on quantum computing is low.

The announce of the imminent advent of the Quantum Computer seems to be recurring every few months these last few years because it's a moving target.

HN recently featured an article about a supposed quantum-only algorithm being applied to normal computing. Algorithms are a vastly larger space to explore than general computing paradigms.

Computer hardware is still advancing forward in performance even though single-threaded performance is stalling in relation.

We're moving away from general computing, this is always happening, but the current environments are pushing us back towards transputers. There's a place for special purpose quantum hardware, but right now the money is in making the most general quantum cpus possible(D-wave being an exception because annealing has many uses where it excels.)

Re: Quantum computers: amazing progress, but probably false supremacy claims

#12
If quantum supremacy was not possible, wouldn't that mean that something is wrong with our physics understanding?

So when people say quantum supremacy is impossible, do they say that the device itself is extremely complicated to build (like an earth to moon elevator for example), or that quantum supremacy isn't allowed not even in principle?

Re: Quantum computers: amazing progress, but probably false supremacy claims

#13

If quantum supremacy was not possible, wouldn't that mean that something is wrong with our physics understanding? So when people say quantum supremacy is impossible, do they say that the device itself is extremely complicated to build (like an earth to moon elevator for example), or that quantum supremacy isn't allowed not even in principle?

I'm not an expert. But a lot of quantum mechanics has to do with things being unknown or completely different until they are measured or observed.

It's possible that there is no way to get useful data from quantum phenomena as anything happening on that level is unknowable by it's very nature.

Re: Quantum computers: amazing progress, but probably false supremacy claims

#14

Earlier quoted context omitted.

No one is saying quantum computing for practical use is upon us. Quantum supremacy is a well defined milestone that doesn't say anything about everyday use of QC.

Yes, that's what I am reading now. A few false experts friends had a very different discourse a few decades ago, but they were probably misled and ignorant. At this point I think it might need a renaming. Quantum device or apparatus maybe? Quantum Computer is a bit misleading...

They are truly programmable computers.

Re: Quantum computers: amazing progress, but probably false supremacy claims

#15

My level of expertise on quantum computing is very low. The announce of the imminent advent of the Quantum Computer seems to be recurring every few months since at least 20 years, at this point I don't care anymore.

As a licensed quantum computologist (um... not really, but I do work for a major QC effort)... your skepticism is not misplaced.

I can only speak for my place of work (not publicly) and pass along scuttlebutt... but, my understanding is that it's largely the same everywhere. Some efforts have tight budgets, some have billions backing them; but QC research is hugely expensive with more unknowns than knowns. People giving out the cash want results sooner than later. At my workplace, the researchers are in a continual pitched battle with management to keep a rein on marketing, limit expectations, etc., and it's a major distraction. When management misunderstands an early result, and oversells it to their superiors (if not the press!), suddenly they think it's appropriate to make "Quantum Supremacy" a task with a 6-month deadline.

It all makes me want to crawl into a box and take a nap.

Re: Quantum computers: amazing progress, but probably false supremacy claims

#16

The usage of the word “supremacy” is probably the primary thing that rubs people the wrong way. When I first heard of it myself, it did feel a little strange. Doing some research into it though, it seems like the phrase and usage of quantum supremacy is pretty well defined and accepted by and large within the physics community. Supposedly the coiner of the term believed “quantum advantage” wouldn’t emphasize the poin…

> The author raises points in contention, but they largely just seem like nitpicks to me.

It doesn't seem just like nitpicks to me. The core issue the author raises is the noise in the final output. If the quantum computer can only produce significantly noisy data (ie not in accordance with the theoretical distribution) whereas the conventional computer produces noiseless data, then that isn't a clear case of quantum supremacy.

Re: Quantum computers: amazing progress, but probably false supremacy claims

#17

If quantum supremacy was not possible, wouldn't that mean that something is wrong with our physics understanding? So when people say quantum supremacy is impossible, do they say that the device itself is extremely complicated to build (like an earth to moon elevator for example), or that quantum supremacy isn't allowed not even in principle?

At the moment the problem of superseding ordinary computers still looks like one of technical/engineering nature. If achieving this is not possible even in principle it could lead to some new developments.

There are some people considering/working on superdeterminism as a possible interpretation of quantum mechanics (the idea that everything, every outcome of an measurement is predetermined by the universe in such a way for us not to gain the complete information about the quantum system. I would not like to discourage anyone, but in fact this would be a conspiracy theory on a cosmic scale. In some discussion on physics stackexchange it was pointed out by Peter Shor that if it were true we wouldn't be able to achieve quantum supremacy.

Re: Quantum computers: amazing progress, but probably false supremacy claims

#18

Earlier quoted context omitted.

Yes, that's what I am reading now. A few false experts friends had a very different discourse a few decades ago, but they were probably misled and ignorant. At this point I think it might need a renaming. Quantum device or apparatus maybe? Quantum Computer is a bit misleading...

They are truly programmable computers.

No that's the funniest aspect of the Google result. They barely have any control over what their gates do.

Gil makes this point, but doesn't call it out: they're claiming supremacy by turning the challenge around. "You can't classically simulate our device (which largely does it's own thing because of issues)."

A kid shoots an arrow at a target. The arrow hits the haybale, but not the target. Suddenly the kid yells "I bet you can't hit my arrow!" and claims Archer Supremacy because nobody even cares to try. Are you impressed? I'm not.

Re: Quantum computers: amazing progress, but probably false supremacy claims

#19

If quantum supremacy was not possible, wouldn't that mean that something is wrong with our physics understanding? So when people say quantum supremacy is impossible, do they say that the device itself is extremely complicated to build (like an earth to moon elevator for example), or that quantum supremacy isn't allowed not even in principle?

You are right - most physicists believe that quantum supremacy is possible, and if we discover that in fact it is not, then we'll need to understand why.

Re: Quantum computers: amazing progress, but probably false supremacy claims

#20

The usage of the word “supremacy” is probably the primary thing that rubs people the wrong way. When I first heard of it myself, it did feel a little strange. Doing some research into it though, it seems like the phrase and usage of quantum supremacy is pretty well defined and accepted by and large within the physics community. Supposedly the coiner of the term believed “quantum advantage” wouldn’t emphasize the poin…

If the points raised by the OP are nitpicks, then I guess it doesn’t matter to you that the sampled (D’) distribution is very close to some easily definable theoretical distribution (D)?

If so I can easily illustrate this “good enough quantum supremacy” in my own home and on a very limited budget. The simple reason is that it is absolutely trivial to set up a physical experiment (quantum or not) where it’s very hard for a computer to sample from the distribution of possible outcomes.

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