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What You Shouldn't Know About Quantum Computers

arxiv.org

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Re: What You Shouldn't Know About Quantum Computers

#61

Post by dumbo-octopus »

NickC25 wrote: post #52
cwillu wrote: post #47

Earlier quoted context omitted.

A QC that can't run Shor's algorithm is not a QC, as much as D-Wave screams and stamps their feet that it's not fair.

I'm a complete layman when it comes to Quantum Computing, but I thought Shor's algorithm is effectively the most basic usecase example of Quantum Computers? I'm confused here.

Yes, but it doesn't work on modern hardware. Too much noise.

Everyone in the industry is basically fully occupied with coming up with a mechanism for active error correction. But based on what I've heard from the folks on the front lines, it's still 10+ years away at minimum.

Re: What You Shouldn't Know About Quantum Computers

#62

Post by dumbo-octopus »

NickC25 wrote: post #55
andrewla wrote: post #3

The article suffers from skipping between layers of abstraction in an attempt to make a point, and in the end in doing so fails to make the initial point. In the first "Myth" section, that "nobody understands this quantum stuff", the example is used of the transistor. It's true that we have no way of making a classical model of a transistor, and our understanding of how transistors work relies on quantum mechanics. B…

> I am in the camp that believes that quantum computing is not possible in any useful sense; in particular a quantum computer will not be capable of being significantly more powerful than a classical computer, in the quantum supremacy sense. Could you elaborate on that? I was under the impression that some companies are using Quantum Computers because quantum supremacy has been demonstrated (such as in molecular mode…

There are no quantum computers in practical use at the moment. This essay^ by IBM (incredibly biased towards making quantum computing seem useful) provides many "visions of"'s and "potential to"'s and "may benefit"'s, but nothing in the present tense.

^https://www.ibm.com/quantum/blog/quantum-working-groups

Re: What You Shouldn't Know About Quantum Computers

#63

Post by shagie »

bawolff wrote: post #54
sampo wrote: post #7

> Researchers like Jaime Sevilla and Jess Riedel support this timeline, publishing a report in late 2020 that claimed a 90% confidence of RSA-2048 being factored before 2060. I am skeptical. 36 years is a long time, but in the past 10 years there hasn't been much progress: year 2001: factorization of 15 (IBM) year 2012: factorization of 21 (University of Bristol) year 2019: factorization of 35 attempt, failed (IBM) h…

> I am skeptical. 36 years is a long time, but in the past 10 years there hasn't been much progress: 36 years ago we didn't even know shor's algorithm existed, and didn't know quantum computers could non-exponentially factor integers at all. So in a certain sense, we have made infinite progress in the last 36 years. Who knows what could happen in the next 36. More generally, i think making science predictions that fa…

https://youtu.be/6qD9XElTpCE

> Hear the story of Shor's Algorithm, straight from the source, Peter Shor.

Shor's part of the story starts in '81.

Though, I generally agree with the it is hard to make predictions that far out. We've got the math to do some higher things, but we still don't have flying cars and fusion power.

Re: What You Shouldn't Know About Quantum Computers

#64

Post by spookie »

zeroonetwothree wrote: post #16
sampo wrote: post #7

> Researchers like Jaime Sevilla and Jess Riedel support this timeline, publishing a report in late 2020 that claimed a 90% confidence of RSA-2048 being factored before 2060. I am skeptical. 36 years is a long time, but in the past 10 years there hasn't been much progress: year 2001: factorization of 15 (IBM) year 2012: factorization of 21 (University of Bristol) year 2019: factorization of 35 attempt, failed (IBM) h…

It’s hard to make predictions, especially about the future.

"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."

Re: What You Shouldn't Know About Quantum Computers

#65

Post by tedunangst »

jessriedel wrote: post #36
sampo wrote: post #7

> Researchers like Jaime Sevilla and Jess Riedel support this timeline, publishing a report in late 2020 that claimed a 90% confidence of RSA-2048 being factored before 2060. I am skeptical. 36 years is a long time, but in the past 10 years there hasn't been much progress: year 2001: factorization of 15 (IBM) year 2012: factorization of 21 (University of Bristol) year 2019: factorization of 35 attempt, failed (IBM) h…

Co-author of the paper here. The “largest integer factored” metric is terrible for several reasons, which is well recognized by researchers and is why people rarely publish those sorts of claims any more. Without net-positive error correction, it’s basically a function of how low your error rate is and how many bits that allows you to compute on with low chance of error, but as soon as the error rate crosses the faul…

Predictions as to the first coprime factored after it has been achieved? Will they publish just rsa-1024, or drop a whole load of factors all at once, eliminate the whole field?

Re: What You Shouldn't Know About Quantum Computers

#66

Post by bigbacaloa »

Etheryte wrote: post #2

At first I thought that the introduction was hyperbole, but the write-up does actually more or less deliver on it. Written in plain English that anyone can grok, it's a good summary of what quantum is, what it isn't, and why you should care. Definitely recommend reading if, like me, you're not too familiar with the field.

[dead]

Re: What You Shouldn't Know About Quantum Computers

#67

Post by nathan_compton »

MrsPeaches wrote: post #5

Chris Ferrie also writes great books about science for babies. https://www.csferrie.com/books https://www.amazon.com/Quantum-Computing-Babies-Baby-Univers...

It might be that I have a Phd in Physics and a long term interest in foundations, but I feel like these books are not very good. Often they emphasize the superficial analogies which physicists use rather than the substantial qualities of the theories.

For example, emphasizing spacetime curvature is, in my opinion, kind of a weird way to talk about the actual substance of general relativity (universal coupling of gravity, futility of trying to describe the world with any fixed four dimensional coordinate system). His quantum mechanics book has similar problems. When I try to explain physics to my young child I always try to get at the essence of the ideas, not the superficial pictures.

Re: What You Shouldn't Know About Quantum Computers

#69

Post by naasking »

sebzim4500 wrote: post #18
andrewla wrote: post #3

The article suffers from skipping between layers of abstraction in an attempt to make a point, and in the end in doing so fails to make the initial point. In the first "Myth" section, that "nobody understands this quantum stuff", the example is used of the transistor. It's true that we have no way of making a classical model of a transistor, and our understanding of how transistors work relies on quantum mechanics. B…

>The final section was of particular interest to me; Gil Kalai's work on quantum error correction is very interesting to me and I am in the camp that believes that quantum computing is not possible in any useful sense; in particular a quantum computer will not be capable of being significantly more powerful than a classical computer, in the quantum supremacy sense. Maybe his arguments have improved over the decades.…

> (i) take it as a point of religious faith that noise will be magically correlated in order to break error correcting codes

This possibility doesn't strike me as any more magical than QM's conjugate variables or its unusual correlations, which also seemed magical to classical physics. Arguably these + contextuality would make noise correlated with the system's configuration in some way, we just don't have a thorough enough understanding of measurement and decoherence to quantify it precisely. I think that's beginning to change, and that we'll have more clarity in the next 10 years or so.

Re: What You Shouldn't Know About Quantum Computers

#70

Post by andrewla »

NickC25 wrote: post #55
andrewla wrote: post #3

The article suffers from skipping between layers of abstraction in an attempt to make a point, and in the end in doing so fails to make the initial point. In the first "Myth" section, that "nobody understands this quantum stuff", the example is used of the transistor. It's true that we have no way of making a classical model of a transistor, and our understanding of how transistors work relies on quantum mechanics. B…

> I am in the camp that believes that quantum computing is not possible in any useful sense; in particular a quantum computer will not be capable of being significantly more powerful than a classical computer, in the quantum supremacy sense. Could you elaborate on that? I was under the impression that some companies are using Quantum Computers because quantum supremacy has been demonstrated (such as in molecular mode…

When I say that quantum computing is not possible, I mean in general. It's a dead end. Note that this belief is subject to being falsified by progress in the field or a demonstration of error correction at scale.

There are companies selling and companies using "Quantum Computers". For example, D-Wave systems sells a computer that uses quantum annealing so solve a class of minimization problems.

To date, there is no quantum computer, in a commercial or a research setting, that has demonstrated it can compute anything faster than a classical computer (this includes the D-Wave systems).

The current trend is to try to establish quantum supremacy (and thus falsify the error correction is impossible thesis) through building extremely simple (non-general purpose) quantum systems. Most recently Google announced a successful attempt that has since been invalidated.

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