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Does anyone know how things are leaning as to whether useful quantum computing is even possible/scalable? I recall reading somewhere that it’s an unanswered que

Does anyone know how things are leaning as to whether useful quantum computing is even possible/scalable? I recall reading somewhere that it’s an unanswered question, and that people are optimistic but it may be that there’s some undiscovered law of information that forbids it.

deepnotderp 8y ago
Gil kalai's argument is essentially that quantum error correction is impossible because he believes that the error will affect too many qubits at once.
- deepnotderp 8y ago
  To clarify, since I can't edit anymore: I don't agree with him, I'm just adding the viewpoint.
greeneggs 8y ago
The broad consensus in the physics community is that quantum computers are in principle scalable (using either software error correction or, speculatively, still-hypothetical topological quantum devices). As for anything, there are of course still some naysayers. (Gil Kalai, mentioned in a sibling comment, is not a physicist and does not have a proposed physical model behind his objections, but his intuition could be correct.) If some undiscovered law of physics forbids it, that would be amazing! A more likely obstacle, though, is that it is just a really hard engineering problem.
randomsearch 8y ago
I’m guessing you mean in the abstract rather than in the short term, but it’s unclear. In the abstract, the jury is still out. I think many scientists would say - yes, provided the hardware guys improve the fidelity of operations and make things scale, it will be possible. But you’re going to need a very large number of qubits to do things like factoring large numbers, and we’re probably going to wait a long time for that. Short term - we’re going to be playing with “toy” examples for now. There’s a lot of focus on achieving “quantum supremacy”, which is a silly term, and finding things small enough and resilient enough to hardware limitations that are also mildly interesting.

deepnotderp 8y ago

Gil kalai's argument is essentially that quantum error correction is impossible because he believes that the error will affect too many qubits at once.

deepnotderp 8y ago
To clarify, since I can't edit anymore: I don't agree with him, I'm just adding the viewpoint.

greeneggs 8y ago

The broad consensus in the physics community is that quantum computers are in principle scalable (using either software error correction or, speculatively, still-hypothetical topological quantum devices). As for anything, there are of course still some naysayers. (Gil Kalai, mentioned in a sibling comment, is not a physicist and does not have a proposed physical model behind his objections, but his intuition could be correct.) If some undiscovered law of physics forbids it, that would be amazing! A more likely obstacle, though, is that it is just a really hard engineering problem.

randomsearch 8y ago

I’m guessing you mean in the abstract rather than in the short term, but it’s unclear. In the abstract, the jury is still out. I think many scientists would say - yes, provided the hardware guys improve the fidelity of operations and make things scale, it will be possible. But you’re going to need a very large number of qubits to do things like factoring large numbers, and we’re probably going to wait a long time for that. Short term - we’re going to be playing with “toy” examples for now. There’s a lot of focus on achieving “quantum supremacy”, which is a silly term, and finding things small enough and resilient enough to hardware limitations that are also mildly interesting.