4 ms·

There are plenty of challenges. In my eyes, the machines are going to require an exponential amount of precision. I don't have any proof, but that's what my ins

There are plenty of challenges. In my eyes, the machines are going to require an exponential amount of precision. I don't have any proof, but that's what my instincts say.

somat 4y ago
It reminds me of why we use digital computers in the first place, there was a period in the 50's where the future of computing was unsure, was it going to be analog or digital? digital won, mainly because the precision required for the components was far far lower. because of this a digital computer could be smaller faster and cheaper than it's analog version. Makes me wonder if quantum computers are just the analog computers of our day.
- kragen 4y ago
  This is a fundamental confusion borne of the historical accident that resulted in digital computers being called "computers" instead of "switches" or "controllers" or "logics" or "coders" or "analytical engines" or "programmable data processors" or something. Analog "computers" are a totally different kind of thing. You can't run a compiler, solve an equation, play chess, or encrypt a message on an analog computer. It's not that they do those things slower or more expensively or in more space than digital "computers"; they just can't do them at all. (Except by simulating a digital computer, of course.) We call computers "computers" because the first ones were built to do what analog "computers" do: numerical integration of ordinary differential equations, like Modelica does. (Eventually they were faster and cheaper than analog computers at that, but it took 20 years in many cases, and even today, we use analog circuits for things like RF downconversion.) But they can also do those other things. In theory, the relationship with quantum computers is kind of similar. Quantum computers can in theory do anything a reversible classical digital computer can do in a similar number of operations, and also some other things (though probably not, say, solve SAT in polynomial time.) And classical digital computers can simulate QC, but as with simulating a digital computer on an analog one, the simulation is so inefficient as to be infeasible in all but trivial cases. But maybe that's backwards? Does it depend on your efficiency metric? Certainly you need quite a lot of GPUs to approach the cost of a dilution refrigerator. We'll see.
  - somat 4y ago
    I suspect that if analog computers ever were developed to the point of being a universal computer(as opposed to the single case computers they were) the stored program and the interior operation would look a lot like what we call neural nets. A bunch of linear algebra nodes interconnected with weighted feedback curves to govern operation.
    - kragen 4y ago
      Universality is inherently digital.
- gatane 4y ago
  Have you seen Veritasium's analog revival video? Some analog systems could be used as cheaper accelerators (like GPUs) for ML.
- edgyquant 4y ago
  Even if this were the case it’d be a tech-tree issue and that’s all. We couldn’t built modern processors without classical computers either but we don’t say we shouldn’t do that. Imo modern classical Processors are a temporary solution that will eventually replace itself with a diverse array of computational architectures that fit different purposes and use cases.
- krastanov 4y ago
  Quantum computers are not analog computers. They are very much digital. A better analogy is with probabilistic computers: classical probabilistic computers are digital computers with a source of random bits. Quantum computers are digital computers in which randomness is governed by quantum probability amplitudes, not by classical probabilities. It is more fruitful to think of quantum computers as digital computers governed by a different, non-classical generalization of probability theory.

There are plenty of challenges. In my eyes, the machines are going to require an exponential amount of precision. I don't have any proof, but that's what my instincts say.

somat 4y ago

It reminds me of why we use digital computers in the first place, there was a period in the 50's where the future of computing was unsure, was it going to be analog or digital? digital won, mainly because the precision required for the components was far far lower. because of this a digital computer could be smaller faster and cheaper than it's analog version. Makes me wonder if quantum computers are just the analog computers of our day.

kragen 4y ago
This is a fundamental confusion borne of the historical accident that resulted in digital computers being called "computers" instead of "switches" or "controllers" or "logics" or "coders" or "analytical engines" or "programmable data processors" or something. Analog "computers" are a totally different kind of thing. You can't run a compiler, solve an equation, play chess, or encrypt a message on an analog computer. It's not that they do those things slower or more expensively or in more space than digital "computers"; they just can't do them at all. (Except by simulating a digital computer, of course.) We call computers "computers" because the first ones were built to do what analog "computers" do: numerical integration of ordinary differential equations, like Modelica does. (Eventually they were faster and cheaper than analog computers at that, but it took 20 years in many cases, and even today, we use analog circuits for things like RF downconversion.) But they can also do those other things. In theory, the relationship with quantum computers is kind of similar. Quantum computers can in theory do anything a reversible classical digital computer can do in a similar number of operations, and also some other things (though probably not, say, solve SAT in polynomial time.) And classical digital computers can simulate QC, but as with simulating a digital computer on an analog one, the simulation is so inefficient as to be infeasible in all but trivial cases. But maybe that's backwards? Does it depend on your efficiency metric? Certainly you need quite a lot of GPUs to approach the cost of a dilution refrigerator. We'll see.
- somat 4y ago
  I suspect that if analog computers ever were developed to the point of being a universal computer(as opposed to the single case computers they were) the stored program and the interior operation would look a lot like what we call neural nets. A bunch of linear algebra nodes interconnected with weighted feedback curves to govern operation.
  - kragen 4y ago
    Universality is inherently digital.
gatane 4y ago
Have you seen Veritasium's analog revival video? Some analog systems could be used as cheaper accelerators (like GPUs) for ML.
edgyquant 4y ago
Even if this were the case it’d be a tech-tree issue and that’s all. We couldn’t built modern processors without classical computers either but we don’t say we shouldn’t do that. Imo modern classical Processors are a temporary solution that will eventually replace itself with a diverse array of computational architectures that fit different purposes and use cases.
krastanov 4y ago
Quantum computers are not analog computers. They are very much digital. A better analogy is with probabilistic computers: classical probabilistic computers are digital computers with a source of random bits. Quantum computers are digital computers in which randomness is governed by quantum probability amplitudes, not by classical probabilities. It is more fruitful to think of quantum computers as digital computers governed by a different, non-classical generalization of probability theory.