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Had to read to the bottom to get to the (really weak) "case against Quantum Computing": > I believe that, appearances to the contrary, the quantum computing fe

Had to read to the bottom to get to the (really weak) "case against Quantum Computing": > I believe that, appearances to the contrary, the quantum computing fervor is nearing its end. That’s because a few decades is the maximum lifetime of any big bubble in technology or science. After a certain period, too many unfulfilled promises have been made, and anyone who has been following the topic starts to get annoyed by further announcements of impending breakthroughs. What’s more, by that time all the tenured faculty positions in the field are already occupied. The proponents have grown older and less zealous, while the younger generation seeks something completely new and more likely to succeed. I was really hoping for a real technical argument, not speculation about bubbles or politics in academia. (Especially given that most of the real research is done in industry.)

resource0x 8y ago
> I was really hoping for a real technical argument Please read the body of the article, not only the bottom. There's plenty of technical arguments in there.
setquk 8y ago
Sounds like Fusion. That’s still going on after 60 odd years.
- powera 8y ago
  With one major difference. We know that fusion in some form is possible (for example, in the sun, or in a hydrogen-bomb). The difficulty is doing it at a reasonable scale. It's less clear that quantum computing is possible.
  - sp332 8y ago
    I mean we already have quantum computers too. https://quantumexperience.ng.bluemix.net/qx/experience https://quantumexperience.ng.bluemix.net/qx/experience The trouble here is also scaling, but in the upward direction.
    - pavelrub 8y ago
      The "quantum computers" we have are classical computers with very weird hardware. The thing everybody is trying to achieve is quantum supremacy - this hasn't been achieved or demonstrated yet, and might never will be.
      - TallGuyShort 8y ago
        For at least a very, very long time, I see Quantum Computers as simply being "accelerators" that do very niche tasks. Like GPUs or FPGAs today. I'm sure one day we'll have a whole other paradigm, but I doubt Quantum Computing as we envision it today will be the thing that replaces x86-compatible silicon.
      - sp332 8y ago
        They are not classical computers. We've had actual quantum logic gates since 1995. https://en.wikipedia.org/wiki/Timeline_of_quantum_computing https://en.wikipedia.org/wiki/Timeline_of_quantum_computing And as linked above, IBM is renting out time on real quantum computers up to 17 qubits now. Intel, Google, and IBM had all announced plans for 49 or 50 qubit computers, which would have achieved quantum supremacy at the time, but IBM improved their simulator to 56 qubits last year. https://en.wikipedia.org/wiki/Quantum_supremacy https://en.wikipedia.org/wiki/Quantum_supremacy So we're only one or two hardware generations away now.
        pavelrub 8y ago
        They are classical computers in the sense they are are no stronger than classical computers - they provide a different physical implementation, but computationally can't achieve anything that a classical computer can't. Everything those "quantum computers" do can be simulated with a classical computer. The entire motivation behind the development of QC is supremacy, and the existence of those "quantum computers" alone doesn't provide any proof that supremacy is possible - so it is definitely not just a question of scale. Google already has a 72 qubit processor (Bristlecone), but whether they or anybody will be able to demonstrate supremacy in the current, next, or some future generation is entirely conjectural. The main limit is error correction, and there are theoretical arguments (Gil Kalai) for why achieving supremacy might be impossible.
  - core-questions 8y ago
    You can literally sign up for D-Wave Leap and run problems on a quantum computer immediately. It's not gate-model, but it's a real quantum annealer that functions and can compute useful things.
    - krastanov 8y ago
      Quantum annealers are not quantum computers. They are not more powerful than classical computers. You either need the "gate model" or the equivalent "adiabatic quantum computing model" to achieve something infeasible on classical computers. It is a common misconception to think that adiabatic quantum computing (which is equivalent to the gate model) and quantum annealing is the same thing. It is not, and quantum annealing is mostly a buzzword that D-Wave use to sell their devices.
- simonh 8y ago
  If something sounds too good to be true, it probably is.
  - tarboreus 8y ago
    Sulfa. White swans do come along, they're just incredibly rare.
    - WillPostForFood 8y ago
      Are they rare, or do they just happen over longer timeframes than we want? Just about any mainstream technology today would appear to be too good to be true to someone ~100 years ago. Air travel, television, computers, phones.
      - tarboreus 8y ago
        The telephone was invented in 1876, practically old hat a hundred years ago. Air travel was 1903, was around longer than Facebook has been around in 2018. I guess it comes down to your definition of rare, but it's certainly rare enough.
    - effie 8y ago
      Black swans are rare.
- Animats 8y ago
  We know that fusion is possible. We have H-bombs. We have various things that do small scale fusion. Getting out more power than is put in remains way out of reach.
  - hazeii 8y ago
    I take the point, while noting H-bombs put out more power than is put in. Perhaps "getting more useful power out..."?
TheOtherHobbes 8y ago
The technical argument is absolutely clear: quantum computing cannot work because it relies on manipulating and measuring an absolutely astronomical number of continuous variables with near-infinite precision. The argument may or may not be correct, but it deserves something more thoughtful than a dismissive response that doesn't even recognise the basic point the author is making.
- krastanov 8y ago
  This is one of the standard complaints (the gist of it being that quantum computing is some form of analog computing, i.e. requiring near-infinite precision). For researchers in the field it becomes rather frustrating to have to repeat the same response without being heard, so I can understand the annoyance expressed in the parent comment. For what is worth, here is a good explanation of how this complaint misrepresents the whole premise of quantum computation (in particular, point 6): https://www.scottaaronson.com/democritus/lec14.html https://www.scottaaronson.com/democritus/lec14.html
  - core-questions 8y ago
    > the gist of it being that quantum computing is some form of analog computing It absolutely is - at least, in the only practical, real-today, working instantiation of it which is in the form of quantum annealing.
    - krastanov 8y ago
      This is an extremely misleading statement. Quantum annealing is most certainly not what quantum computing is about (it is not particularly "quantum" either). At most, you can argue that it is an important first step (which is also doubtful). Most of the interesting hardware currently being developed has nothing to do with quantum annealing and most researchers are fairly annoyed at D-wave for originally pushing this nonsense (D-wave is the company that started selling quantum annealing machines, which are little more than a classical analog computer). See the ion traps developed in the UK/Maryland or the transmon qubits at Google/IBM/Yale for some well known prototypes of quantum computing hardware (which are admittedly quite far from being practical or usable).
scottlocklin 8y ago
There's certainly a bubble here; trivially obvious, but there are also very good technical arguments in that article. FWIIW Dyakonov has been saying the same thing since the bubble got started in 2000 or so.

resource0x 8y ago

> I was really hoping for a real technical argument Please read the body of the article, not only the bottom. There's plenty of technical arguments in there.

setquk 8y ago

Sounds like Fusion. That’s still going on after 60 odd years.

powera 8y ago
With one major difference. We know that fusion in some form is possible (for example, in the sun, or in a hydrogen-bomb). The difficulty is doing it at a reasonable scale. It's less clear that quantum computing is possible.
- sp332 8y ago
  I mean we already have quantum computers too. https://quantumexperience.ng.bluemix.net/qx/experience https://quantumexperience.ng.bluemix.net/qx/experience The trouble here is also scaling, but in the upward direction.
  - pavelrub 8y ago
    The "quantum computers" we have are classical computers with very weird hardware. The thing everybody is trying to achieve is quantum supremacy - this hasn't been achieved or demonstrated yet, and might never will be.
    - TallGuyShort 8y ago
      For at least a very, very long time, I see Quantum Computers as simply being "accelerators" that do very niche tasks. Like GPUs or FPGAs today. I'm sure one day we'll have a whole other paradigm, but I doubt Quantum Computing as we envision it today will be the thing that replaces x86-compatible silicon.
    - sp332 8y ago
      They are not classical computers. We've had actual quantum logic gates since 1995. https://en.wikipedia.org/wiki/Timeline_of_quantum_computing https://en.wikipedia.org/wiki/Timeline_of_quantum_computing And as linked above, IBM is renting out time on real quantum computers up to 17 qubits now. Intel, Google, and IBM had all announced plans for 49 or 50 qubit computers, which would have achieved quantum supremacy at the time, but IBM improved their simulator to 56 qubits last year. https://en.wikipedia.org/wiki/Quantum_supremacy https://en.wikipedia.org/wiki/Quantum_supremacy So we're only one or two hardware generations away now.
      - pavelrub 8y ago
        They are classical computers in the sense they are are no stronger than classical computers - they provide a different physical implementation, but computationally can't achieve anything that a classical computer can't. Everything those "quantum computers" do can be simulated with a classical computer. The entire motivation behind the development of QC is supremacy, and the existence of those "quantum computers" alone doesn't provide any proof that supremacy is possible - so it is definitely not just a question of scale. Google already has a 72 qubit processor (Bristlecone), but whether they or anybody will be able to demonstrate supremacy in the current, next, or some future generation is entirely conjectural. The main limit is error correction, and there are theoretical arguments (Gil Kalai) for why achieving supremacy might be impossible.
- core-questions 8y ago
  You can literally sign up for D-Wave Leap and run problems on a quantum computer immediately. It's not gate-model, but it's a real quantum annealer that functions and can compute useful things.
  - krastanov 8y ago
    Quantum annealers are not quantum computers. They are not more powerful than classical computers. You either need the "gate model" or the equivalent "adiabatic quantum computing model" to achieve something infeasible on classical computers. It is a common misconception to think that adiabatic quantum computing (which is equivalent to the gate model) and quantum annealing is the same thing. It is not, and quantum annealing is mostly a buzzword that D-Wave use to sell their devices.
simonh 8y ago
If something sounds too good to be true, it probably is.
- tarboreus 8y ago
  Sulfa. White swans do come along, they're just incredibly rare.
  - WillPostForFood 8y ago
    Are they rare, or do they just happen over longer timeframes than we want? Just about any mainstream technology today would appear to be too good to be true to someone ~100 years ago. Air travel, television, computers, phones.
    - tarboreus 8y ago
      The telephone was invented in 1876, practically old hat a hundred years ago. Air travel was 1903, was around longer than Facebook has been around in 2018. I guess it comes down to your definition of rare, but it's certainly rare enough.
  - effie 8y ago
    Black swans are rare.
Animats 8y ago
We know that fusion is possible. We have H-bombs. We have various things that do small scale fusion. Getting out more power than is put in remains way out of reach.
- hazeii 8y ago
  I take the point, while noting H-bombs put out more power than is put in. Perhaps "getting more useful power out..."?

TheOtherHobbes 8y ago

The technical argument is absolutely clear: quantum computing cannot work because it relies on manipulating and measuring an absolutely astronomical number of continuous variables with near-infinite precision. The argument may or may not be correct, but it deserves something more thoughtful than a dismissive response that doesn't even recognise the basic point the author is making.

krastanov 8y ago
This is one of the standard complaints (the gist of it being that quantum computing is some form of analog computing, i.e. requiring near-infinite precision). For researchers in the field it becomes rather frustrating to have to repeat the same response without being heard, so I can understand the annoyance expressed in the parent comment. For what is worth, here is a good explanation of how this complaint misrepresents the whole premise of quantum computation (in particular, point 6): https://www.scottaaronson.com/democritus/lec14.html https://www.scottaaronson.com/democritus/lec14.html
- core-questions 8y ago
  > the gist of it being that quantum computing is some form of analog computing It absolutely is - at least, in the only practical, real-today, working instantiation of it which is in the form of quantum annealing.
  - krastanov 8y ago
    This is an extremely misleading statement. Quantum annealing is most certainly not what quantum computing is about (it is not particularly "quantum" either). At most, you can argue that it is an important first step (which is also doubtful). Most of the interesting hardware currently being developed has nothing to do with quantum annealing and most researchers are fairly annoyed at D-wave for originally pushing this nonsense (D-wave is the company that started selling quantum annealing machines, which are little more than a classical analog computer). See the ion traps developed in the UK/Maryland or the transmon qubits at Google/IBM/Yale for some well known prototypes of quantum computing hardware (which are admittedly quite far from being practical or usable).

scottlocklin 8y ago

There's certainly a bubble here; trivially obvious, but there are also very good technical arguments in that article. FWIIW Dyakonov has been saying the same thing since the bubble got started in 2000 or so.