3 ms·

As a practitioner in the field of quantum computation, my advice is to be very careful with intuition. Quantum computers are among some of the most complex pie

As a practitioner in the field of quantum computation, my advice is to be very careful with intuition. Quantum computers are among some of the most complex pieces of engineering. They generally require a relatively sophisticated understanding of mathematics and physics, much of which is very non-intuitive (e.g., high-dimensional Lie groups, random probability distributions of probability distributions, low-temperature thermodynamics, ...). Piecing it all together requires careful threading. I think Gil’s notes don’t represent the pinnacle of rigorous care, but it is a useful “punch list” of broad considerations worth talking about. I am not questioning your or anybody’s intuition directly or personally, but it’s easy—especially for the tech-savvy world of software engineers that frequent HN—to jump to conclusions based off of our intuitions about the mechanics and failure of (classical) systems and make (baseless) conclusions about contemporary quantum ones.

KKKKkkkk1 6y ago
I'm doing a thought experiment. What if Prof. Kalai is right? The field of quantum computation at this point has people who attained titles like "Centennial Professor" and "Director of Engineering and Distinguished Scientist." People are on their way to make careers that will rival the luminaries of AI (another field that has not delivered even 1% of what it has promised). What would it take for these folks to acknowledge that it's not working out and find something more productive for themselves to do?
- reikonomusha 6y ago
  If there will be losers in the event of robust quantum computation not being realizable, they will likely be individuals who are working in the commercialization of the technology, not those academically involved in fundamental research. Programs at Google, Rigetti, IBM, D-Wave, Q-CTRL, Zapata, Horizon QC, Xanadu, etc. are all existentially tied to quantum computing through their business models[1] and they would have the financial incentive to “hold out”[2] on or not entertain opponents seriously. I think somebody like Scott Aaronson—who has made an academic career in computer science and quantum computing—would gladly accept reality were it not to be what he hopes it is, and would be entirely willing to stand on a platform and broadcast the truth. Aaronson is in the business of understanding fundamental truths about computation, not (as far as anybody knows) being a shill for big business. [1] Disclaimer: I’m not deeply familiar business-wise with all the companies listed, so take my “existential tie” with a grain of salt. [2] I’m not claiming that any of these companies would conduct business dishonestly in the event that they were “wrong”.
  - dia80 6y ago
    I'm sure your comment is written in excellent faith after some reflection. While i am unable to weigh in on the issue at hand I would offer a few cautionary scraps about luminaries of a field being able to accept it's wrong. The Intelligence Trap[1] is an excellent book that among other things explains how being very clever can make it harder to get at the truth. Formidable intellects can patch any holes that appear in their world view by constructing convincing and credible arguements. "Science advances on funeral at time" paraphrased from Max Planck - the individuals he was thinking of were truth seeking super brains as well. [1] https://www.goodreads.com/book/show/41817546-the-intelligence-trap https://www.goodreads.com/book/show/41817546-the-intelligenc...
ShorsHammer 6y ago
> among some of the most complex pieces of engineering Do you think it will end up in the "20 years from now" category like many other technologies? I'm on the fence regarding how fast we can actually advance, QC is tough. I've seen the same things said about fusion energy. Fusion is fairly simple, you can do it in your garage right now if you were so inclined, however getting net positive output is truly pushing the limits of what we know and can build. Quantum Computers have far more going on in comparison.
- reikonomusha 6y ago
  Right now QCs are advancing. It’s possible to forever advance but still be going up against an unfavorable asymptote over which you’re unable to cross, of course, but year after year, qubit fidelities are increasing, error rates are dropping, qubit counts are increasing, and the zoo of quantum technologies (superconducting qubits, ions, neutral atoms, photons, and silicon dots... among others) are blossoming. I’m “bullish” on the whole thing. In my opinion, it would be hugely unwise for anybody in the field right now to call it quits without seeing the technology through further. There are too many “interesting” developments happening. I think that in about a year we will know the true nature of the Google supremacy claims as experts from many disciplines both stew and weigh in on the matter. If supremacy (continues to) hold up, that would be evidence against the “20 years away” sentiment. I agree with what you said, QC has a lot more going on / going for it than fusion does. They both still reside in roughly the same “technological class”, but QC at least seems to be improving regularly with a combination of steady engineering as well as scientific breakthroughs.
- roenxi 6y ago
  Sometimes stuff that is 20 years from now happens in 20 years. They're up past 50 qbits and it looks like it might be another exponential growth process with doubling time ~4 years [0]. [0] https://s3.amazonaws.com/cbi-research-portal-uploads/2019/01/14180930/quantum-computing-qubit-timeline-1024x768.png https://s3.amazonaws.com/cbi-research-portal-uploads/2019/01...
  - fsh 6y ago
    Counting qubits is not a useful metric. Google actually had to go back down from 72 to 53 in order to get their quantum supremacy experiment working. Also none of these machines are error-corrected, so they cannot run useful quantum algorithms such as Shor's or Grover's algorithm. It is still an open question whether large error-corrected quantum computers are at all possible.

KKKKkkkk1 6y ago

I'm doing a thought experiment. What if Prof. Kalai is right? The field of quantum computation at this point has people who attained titles like "Centennial Professor" and "Director of Engineering and Distinguished Scientist." People are on their way to make careers that will rival the luminaries of AI (another field that has not delivered even 1% of what it has promised). What would it take for these folks to acknowledge that it's not working out and find something more productive for themselves to do?

reikonomusha 6y ago
If there will be losers in the event of robust quantum computation not being realizable, they will likely be individuals who are working in the commercialization of the technology, not those academically involved in fundamental research. Programs at Google, Rigetti, IBM, D-Wave, Q-CTRL, Zapata, Horizon QC, Xanadu, etc. are all existentially tied to quantum computing through their business models[1] and they would have the financial incentive to “hold out”[2] on or not entertain opponents seriously. I think somebody like Scott Aaronson—who has made an academic career in computer science and quantum computing—would gladly accept reality were it not to be what he hopes it is, and would be entirely willing to stand on a platform and broadcast the truth. Aaronson is in the business of understanding fundamental truths about computation, not (as far as anybody knows) being a shill for big business. [1] Disclaimer: I’m not deeply familiar business-wise with all the companies listed, so take my “existential tie” with a grain of salt. [2] I’m not claiming that any of these companies would conduct business dishonestly in the event that they were “wrong”.
- dia80 6y ago
  I'm sure your comment is written in excellent faith after some reflection. While i am unable to weigh in on the issue at hand I would offer a few cautionary scraps about luminaries of a field being able to accept it's wrong. The Intelligence Trap[1] is an excellent book that among other things explains how being very clever can make it harder to get at the truth. Formidable intellects can patch any holes that appear in their world view by constructing convincing and credible arguements. "Science advances on funeral at time" paraphrased from Max Planck - the individuals he was thinking of were truth seeking super brains as well. [1] https://www.goodreads.com/book/show/41817546-the-intelligence-trap https://www.goodreads.com/book/show/41817546-the-intelligenc...

ShorsHammer 6y ago

> among some of the most complex pieces of engineering Do you think it will end up in the "20 years from now" category like many other technologies? I'm on the fence regarding how fast we can actually advance, QC is tough. I've seen the same things said about fusion energy. Fusion is fairly simple, you can do it in your garage right now if you were so inclined, however getting net positive output is truly pushing the limits of what we know and can build. Quantum Computers have far more going on in comparison.

reikonomusha 6y ago
Right now QCs are advancing. It’s possible to forever advance but still be going up against an unfavorable asymptote over which you’re unable to cross, of course, but year after year, qubit fidelities are increasing, error rates are dropping, qubit counts are increasing, and the zoo of quantum technologies (superconducting qubits, ions, neutral atoms, photons, and silicon dots... among others) are blossoming. I’m “bullish” on the whole thing. In my opinion, it would be hugely unwise for anybody in the field right now to call it quits without seeing the technology through further. There are too many “interesting” developments happening. I think that in about a year we will know the true nature of the Google supremacy claims as experts from many disciplines both stew and weigh in on the matter. If supremacy (continues to) hold up, that would be evidence against the “20 years away” sentiment. I agree with what you said, QC has a lot more going on / going for it than fusion does. They both still reside in roughly the same “technological class”, but QC at least seems to be improving regularly with a combination of steady engineering as well as scientific breakthroughs.
roenxi 6y ago
Sometimes stuff that is 20 years from now happens in 20 years. They're up past 50 qbits and it looks like it might be another exponential growth process with doubling time ~4 years [0]. [0] https://s3.amazonaws.com/cbi-research-portal-uploads/2019/01/14180930/quantum-computing-qubit-timeline-1024x768.png https://s3.amazonaws.com/cbi-research-portal-uploads/2019/01...
- fsh 6y ago
  Counting qubits is not a useful metric. Google actually had to go back down from 72 to 53 in order to get their quantum supremacy experiment working. Also none of these machines are error-corrected, so they cannot run useful quantum algorithms such as Shor's or Grover's algorithm. It is still an open question whether large error-corrected quantum computers are at all possible.