8 ms·

Quantum supremacy: the gloves are off

275 points by furcyd 7y ago

muizelaar 7y ago
http://archive.is/3ajcQ http://archive.is/3ajcQ
- quakeguy 7y ago
  Thx! Blog is already down for me.
  - j1vms 7y ago
    He might just need a static-site blog from this point on.
leoh 7y ago
Two key points: > OK, so let’s carefully spell out what the IBM paper says. They argue that, by commandeering the full attention of Summit at Oak Ridge National Lab, the most powerful supercomputer that currently exists on Earth—one that fills the area of two basketball courts, and that (crucially) has 250 petabytes of hard disk space—one could just barely store the entire quantum state vector of Google’s 53-qubit Sycamore chip in hard disk. And once one had done that, one could simulate the chip in ~2.5 days, more-or-less just by updating the entire state vector by brute force, rather than the 10,000 years that Google had estimated on the basis of my and Lijie Chen’s “Schrödinger-Feynman algorithm” (which can get by with less memory). > But does IBM’s analysis mean that “quantum supremacy” hasn’t been achieved? No, it doesn’t—at least, not under any definition of “quantum supremacy” that I’ve ever used.
- revel 7y ago
  Process arguments are rarely convincing and particularly not when the process is so technically complex.
ThePhysicist 7y ago
Regardless of whether the Martinis team actually demonstrated quantum supremacy, their achievement is undoubtedly worth the praise it received. I built and operated a superconducting two-qubit processor for my PhD thesis in 2010, so I have a good understanding of the challenges invovled in operating and tuning qubits. For me, seeing the 53 qubit chip, its wiring setup and the control electronics is just breathtaking. I think John's team neatly demonstrated that they are far ahead of the competition (e.g. Rigetti, IBM) in terms of maturity and qubit control, and if that's any indication of future success I would strongly bet on their team for building the first actually working quantum computer.
- rrss 7y ago
  What is a "first actually working quantum computer" if not this Sycamore device that Google used to demonstrate quantum supremacy?
  - Laakeri 7y ago
    Maybe something that solves a natural problem instead of an artificial one.
  - SAI_Peregrinus 7y ago
    One with fault-tolerance.
  - 317070 7y ago
    I reckon one that has quantum error correction on qubits which present Boolean values. I.e. one which could also run a classical program. That is the quantum computer which is actually a quantum Turing machine and which can do speedups of e.g. factorization. Unfortunately, it is hypothesized that such a quantum Turing machine will require about ~1000 qubits of this machine per qubit with error correction, maybe more.
    - kulahan 7y ago
      For what it's worth, the FAQ on his blog dances around this topic: "Running Shor’s algorithm to break the RSA cryptosystem would require several thousand logical qubits. With known error-correction methods, that could easily translate into millions of physical qubits, and those probably of a higher quality than any that exist today."
pyentropy 7y ago
Scott Aaronson is probably one of the most underrated scientists of our time. He's very approachable and has responded to comments and emails of undergrads like me in a few hours. Not only is he part of the team that practically invented quantum supremacy, but his blog is the most informative blog out there for ethics, morality, nerdiness, theoretical computer science and the philosophical implications of complexity theory. Y Combinator had a podcast with him which you can watch here: https://www.youtube.com/watch?v=0jrybODBUpA https://www.youtube.com/watch?v=0jrybODBUpA
- ivalm 7y ago
  I enjoy Aaronson's blog/interviews, but he is not an "underrated scientist", he is perhaps an underrated science communicator. Being a science communicator, however, is somewhat unrelated to being a scientist. Looking at his actual scientific work, he is in fact doing good work, but he is not in the same league as, let's say, Peter Shor.
  - pyentropy 7y ago
    I think his BosonSampling method comes very close to Shor's algorithm, and I don't think "leagues" really exist in academic output - but he's not doing good work - he's doing great work.
dang 7y ago
There are three threads. The others are: Google's post https://news.ycombinator.com/item?id=21332768 https://news.ycombinator.com/item?id=21332768 IBM's critique https://news.ycombinator.com/item?id=21333105 https://news.ycombinator.com/item?id=21333105
naringas 7y ago
I still don't understand what the hell is "quantum computing". I think my problem is my own conception of classical computing. My best approximation for what a quantum computer actually is. Is that it's some sort of device to set quantum states, then run a "quantum algorithm" (i.e. a graph of "quantum logic gates"), and finally read out the "quantum bits" resulting from the algorithm. That sounds a lot more like a sensor to me. Also all the problems with noise and calibration reinforce my notion that it's more like a sensor than a computer. But to be fair I barely understand "classical computing". I think my personal notion relies too much on badly defined ideas about "the run-time" of a computer program (some software) that I have constructed from "industry" experience. To me big huge fundamental part of computing has to do with arbitrarily representing anything with a symbolic alphabet. And then automatically manipulating this symbolic alphabet to get a result with can be "mapped back" through the initial arbitrary representation so we learn something about whatever we initially chose to represent. Maybe that's not computing? but then what is that? and then what is computing?? Try as I might I cannot reconcile my understanding of classical computing with quantum computing.
- Strilanc 7y ago
  Here's a youtube video that might be at just the right level for you: https://www.youtube.com/watch?v=ZoT82NDpcvQ https://www.youtube.com/watch?v=ZoT82NDpcvQ . Basically it goes over the simplest quantum-vs-classical query advantage (1 instead of 2) that was ever found.
- travisoneill1 7y ago
  Is that different than a regular computer? To take your statement and slightly modify it: some sort of device to set electromagnetic charges, then run an "electromagnetic algorithm" (i.e. a graph of "electromagnetic logic gates"), and finally read out the "sequence of electromagnetic bits" resulting from the algorithm. That sounds to me like the computer that I am typing on now. Am I missing something here?
  - outworlder 7y ago
    > Is that different than a regular computer Not very. Using their definition, logic gates, RAM, Flash or Hard Disks could all be redefined as "sensors".
knzhou 7y ago
As always, thank god for Scott Aaronson's blog! There is a lot of misinformation sown in popular science. Shtetl Optimized is just about the only science-related source that is simultaneously correct, accessible, timely, and widely read. That's incredible in a world where 99% of sources barely achieve two of these goals.
X6S1x6Okd1st 7y ago
So assuming that people take the economic loss and switch to public key encryption schemes that appear quantum hardened what's the next most interesting thing to do with a quantum computer?
- deleted 7y ago
  [deleted]
- deepnotderp 7y ago
  Quadratic speedup over any black box function is pretty nice. Could certainly help ML a lot.
  - X6S1x6Okd1st 7y ago
    Could you elaborate? If the function is XOR I'm pretty sure you won't see a speed up
    - hatsunearu 7y ago
      He's referring to Grover's algorithm.
mandukya 7y ago
This is a very well written article which goes indepth in explaining the current developments from a 3rd party perspective
aaron695 7y ago
> most obviously, the paper from IBM (see also their blog post) saying that they could simulate the Google experiment in 2.5 days, rather than the 10,000 years that Google had estimated. Not really.... they say - "We argue that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity. This is in fact a conservative, worst-case estimate, and we expect that with additional refinements the classical cost of the simulation can be further reduced." > Will we find out next that Google’s benchmark can be classically spoofed in mere milliseconds? > Well, no one can rule that out, but we do have some reasons to think that it’s unlikely—and crucially, that even if it turned out to be true, one would just have to add 10 or 20 or 30 more qubits to make it no longer true. Could we explain why Google didn't just add 30 more qubits then? Why did they chose 10,000 years which is not long in Moore's law? Why not 1000 billion years to make sure they wiped the floor? To me the reason is something would fall apart. They could do what they could do because it was within the bounds of a classical system. If this is not the case then it needs explaining.
dmix 7y ago
> we cared about the increase in the speedup as D-Wave upgraded its hardware, and the trouble was that we never saw a convincing case that there would be one. Is D-Wave still doing useful work in the field? I've been meaning to read up on them and recent progress quantum in general... I still see D-Wave in the news often in the tech press and Canadian media.

275 points by furcyd 7y ago

muizelaar 7y ago

http://archive.is/3ajcQ http://archive.is/3ajcQ

quakeguy 7y ago
Thx! Blog is already down for me.
- j1vms 7y ago
  He might just need a static-site blog from this point on.

leoh 7y ago

Two key points: > OK, so let’s carefully spell out what the IBM paper says. They argue that, by commandeering the full attention of Summit at Oak Ridge National Lab, the most powerful supercomputer that currently exists on Earth—one that fills the area of two basketball courts, and that (crucially) has 250 petabytes of hard disk space—one could just barely store the entire quantum state vector of Google’s 53-qubit Sycamore chip in hard disk. And once one had done that, one could simulate the chip in ~2.5 days, more-or-less just by updating the entire state vector by brute force, rather than the 10,000 years that Google had estimated on the basis of my and Lijie Chen’s “Schrödinger-Feynman algorithm” (which can get by with less memory). > But does IBM’s analysis mean that “quantum supremacy” hasn’t been achieved? No, it doesn’t—at least, not under any definition of “quantum supremacy” that I’ve ever used.

revel 7y ago
Process arguments are rarely convincing and particularly not when the process is so technically complex.

ThePhysicist 7y ago

Regardless of whether the Martinis team actually demonstrated quantum supremacy, their achievement is undoubtedly worth the praise it received. I built and operated a superconducting two-qubit processor for my PhD thesis in 2010, so I have a good understanding of the challenges invovled in operating and tuning qubits. For me, seeing the 53 qubit chip, its wiring setup and the control electronics is just breathtaking. I think John's team neatly demonstrated that they are far ahead of the competition (e.g. Rigetti, IBM) in terms of maturity and qubit control, and if that's any indication of future success I would strongly bet on their team for building the first actually working quantum computer.

rrss 7y ago
What is a "first actually working quantum computer" if not this Sycamore device that Google used to demonstrate quantum supremacy?
- Laakeri 7y ago
  Maybe something that solves a natural problem instead of an artificial one.
- SAI_Peregrinus 7y ago
  One with fault-tolerance.
- 317070 7y ago
  I reckon one that has quantum error correction on qubits which present Boolean values. I.e. one which could also run a classical program. That is the quantum computer which is actually a quantum Turing machine and which can do speedups of e.g. factorization. Unfortunately, it is hypothesized that such a quantum Turing machine will require about ~1000 qubits of this machine per qubit with error correction, maybe more.
  - kulahan 7y ago
    For what it's worth, the FAQ on his blog dances around this topic: "Running Shor’s algorithm to break the RSA cryptosystem would require several thousand logical qubits. With known error-correction methods, that could easily translate into millions of physical qubits, and those probably of a higher quality than any that exist today."

pyentropy 7y ago

Scott Aaronson is probably one of the most underrated scientists of our time. He's very approachable and has responded to comments and emails of undergrads like me in a few hours. Not only is he part of the team that practically invented quantum supremacy, but his blog is the most informative blog out there for ethics, morality, nerdiness, theoretical computer science and the philosophical implications of complexity theory. Y Combinator had a podcast with him which you can watch here: https://www.youtube.com/watch?v=0jrybODBUpA https://www.youtube.com/watch?v=0jrybODBUpA

ivalm 7y ago
I enjoy Aaronson's blog/interviews, but he is not an "underrated scientist", he is perhaps an underrated science communicator. Being a science communicator, however, is somewhat unrelated to being a scientist. Looking at his actual scientific work, he is in fact doing good work, but he is not in the same league as, let's say, Peter Shor.
- pyentropy 7y ago
  I think his BosonSampling method comes very close to Shor's algorithm, and I don't think "leagues" really exist in academic output - but he's not doing good work - he's doing great work.

dang 7y ago

There are three threads. The others are: Google's post https://news.ycombinator.com/item?id=21332768 https://news.ycombinator.com/item?id=21332768 IBM's critique https://news.ycombinator.com/item?id=21333105 https://news.ycombinator.com/item?id=21333105

naringas 7y ago

I still don't understand what the hell is "quantum computing". I think my problem is my own conception of classical computing. My best approximation for what a quantum computer actually is. Is that it's some sort of device to set quantum states, then run a "quantum algorithm" (i.e. a graph of "quantum logic gates"), and finally read out the "quantum bits" resulting from the algorithm. That sounds a lot more like a sensor to me. Also all the problems with noise and calibration reinforce my notion that it's more like a sensor than a computer. But to be fair I barely understand "classical computing". I think my personal notion relies too much on badly defined ideas about "the run-time" of a computer program (some software) that I have constructed from "industry" experience. To me big huge fundamental part of computing has to do with arbitrarily representing anything with a symbolic alphabet. And then automatically manipulating this symbolic alphabet to get a result with can be "mapped back" through the initial arbitrary representation so we learn something about whatever we initially chose to represent. Maybe that's not computing? but then what is that? and then what is computing?? Try as I might I cannot reconcile my understanding of classical computing with quantum computing.

Strilanc 7y ago
Here's a youtube video that might be at just the right level for you: https://www.youtube.com/watch?v=ZoT82NDpcvQ https://www.youtube.com/watch?v=ZoT82NDpcvQ . Basically it goes over the simplest quantum-vs-classical query advantage (1 instead of 2) that was ever found.
travisoneill1 7y ago
Is that different than a regular computer? To take your statement and slightly modify it: some sort of device to set electromagnetic charges, then run an "electromagnetic algorithm" (i.e. a graph of "electromagnetic logic gates"), and finally read out the "sequence of electromagnetic bits" resulting from the algorithm. That sounds to me like the computer that I am typing on now. Am I missing something here?
- outworlder 7y ago
  > Is that different than a regular computer Not very. Using their definition, logic gates, RAM, Flash or Hard Disks could all be redefined as "sensors".

knzhou 7y ago

As always, thank god for Scott Aaronson's blog! There is a lot of misinformation sown in popular science. Shtetl Optimized is just about the only science-related source that is simultaneously correct, accessible, timely, and widely read. That's incredible in a world where 99% of sources barely achieve two of these goals.

X6S1x6Okd1st 7y ago

So assuming that people take the economic loss and switch to public key encryption schemes that appear quantum hardened what's the next most interesting thing to do with a quantum computer?

deleted 7y ago
[deleted]
deepnotderp 7y ago
Quadratic speedup over any black box function is pretty nice. Could certainly help ML a lot.
- X6S1x6Okd1st 7y ago
  Could you elaborate? If the function is XOR I'm pretty sure you won't see a speed up
  - hatsunearu 7y ago
    He's referring to Grover's algorithm.

mandukya 7y ago

This is a very well written article which goes indepth in explaining the current developments from a 3rd party perspective

aaron695 7y ago

> most obviously, the paper from IBM (see also their blog post) saying that they could simulate the Google experiment in 2.5 days, rather than the 10,000 years that Google had estimated. Not really.... they say - "We argue that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity. This is in fact a conservative, worst-case estimate, and we expect that with additional refinements the classical cost of the simulation can be further reduced." > Will we find out next that Google’s benchmark can be classically spoofed in mere milliseconds? > Well, no one can rule that out, but we do have some reasons to think that it’s unlikely—and crucially, that even if it turned out to be true, one would just have to add 10 or 20 or 30 more qubits to make it no longer true. Could we explain why Google didn't just add 30 more qubits then? Why did they chose 10,000 years which is not long in Moore's law? Why not 1000 billion years to make sure they wiped the floor? To me the reason is something would fall apart. They could do what they could do because it was within the bounds of a classical system. If this is not the case then it needs explaining.

dmix 7y ago

> we cared about the increase in the speedup as D-Wave upgraded its hardware, and the trouble was that we never saw a convincing case that there would be one. Is D-Wave still doing useful work in the field? I've been meaning to read up on them and recent progress quantum in general... I still see D-Wave in the news often in the tech press and Canadian media.