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I have been told that D-Wave is not actually a quantum computer but a quantum annealer, but I don't know the difference.

sigmaprimus 10y ago
I have also heard that it is not a true Quantum computer although it solves the ising problem faster than simulated annealING systems and it also uses qBits (>1024 atm) and I believe both Google and UCLA own or at least use Dwave systems. So if it looks like a duck and quacks like a duck.... Anyways nice article even if it did not mention Dwave. The Hacker News community comments section can take care of that!!
- kurthr 10y ago
  They really aren't all that similar, and it only solves a tiny subset of Ising problems (which match D-Wave topology), and they really aren't faster than a single modern Intel core running a reasonable algorithm. http://www.scottaaronson.com/blog/?p=2555 http://www.scottaaronson.com/blog/?p=2555
- marcosdumay 10y ago
  It can not factorize numbers in polynomial time, it can not speed-up chemical simulations, it can do basically nothing that a quantum computer does, besides simulating itself. It's also not obvious in any way what use there is in simulating quantum annealing.
  - kobeya 10y ago
    Search. You can use quantum annealing for unstructured search.
    - marcosdumay 10y ago
      AFAIK (but I'm not up-to-date on the area) nobody has ever showed that quantum annealing is any faster than classical annealing.
      - kobeya 10y ago
        If you mean the D-wave devices specifically, the kerfuffle is that the low-clockrate quantum device does not complete tasks any faster or cheaper than a comparably priced classical computer, and the open question as to whether they can ever be made to operate faster. That's why there's only research labs buying them. But the device does work.
kale 10y ago
I'm not an expert in the field, but I do annealing work on occasion (simulated annealing, which is kind of like copying polymer annealing). Simulated annealing is just an optimization. I use it for modelling human motion. You have the position and acceleration of each bone in the legs and feet. You start by deciding on a variable (say, reducing energy expenditure for gait), and then letting the algorithm alter variables and attempt to minimize a variable. So if quantum annealing is anything like simulated annealing, you aren't "solving" for a single, correct answer, but getting a solution that minimizes or maximizes an outcome faster than brute force. So a quantum computer could solve "What is the factorization of this huge number?", while quantum annealing could solve "Given these 30 different engine configurations, which combination of intake pressure, fuel flow rate, turbocharger performance curve, and engine timing would result in the best fuel efficiency?"
- sp332 10y ago
  The advantage of a quantum annealer is in cases where there is a large, narrow spike in the way of moving to a good solution. The quantum optimizer has a chance of "tunneling" through the spike to find a better solution. A classical version of simulated annealing would have to "climb" over the spike, or more likely just be stuck on the wrong side.
- Ar-Curunir 10y ago
  Optimisation and Search problems are not fundamentally different; one can usually translate a problem from one world to another. For instance, take your optimisation problem and rephrase it as: Here's a value of the fuel efficiency; find me a setting of the parameters that achieves a fuel efficiency better than that. It's now a search problem. To find the best fuel efficiency, just binary search over possible values of the efficiency. Where D-Wave differs is that you can only solve a particular kind of optimisation problem, and this kind of problem can't encode general computation. General quantum computers can solve general computation problems, not just the simulated annealing of D-Wave QC.
deleted 10y ago
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sigmaprimus 10y ago

I have also heard that it is not a true Quantum computer although it solves the ising problem faster than simulated annealING systems and it also uses qBits (>1024 atm) and I believe both Google and UCLA own or at least use Dwave systems. So if it looks like a duck and quacks like a duck.... Anyways nice article even if it did not mention Dwave. The Hacker News community comments section can take care of that!!

kurthr 10y ago
They really aren't all that similar, and it only solves a tiny subset of Ising problems (which match D-Wave topology), and they really aren't faster than a single modern Intel core running a reasonable algorithm. http://www.scottaaronson.com/blog/?p=2555 http://www.scottaaronson.com/blog/?p=2555
marcosdumay 10y ago
It can not factorize numbers in polynomial time, it can not speed-up chemical simulations, it can do basically nothing that a quantum computer does, besides simulating itself. It's also not obvious in any way what use there is in simulating quantum annealing.
- kobeya 10y ago
  Search. You can use quantum annealing for unstructured search.
  - marcosdumay 10y ago
    AFAIK (but I'm not up-to-date on the area) nobody has ever showed that quantum annealing is any faster than classical annealing.
    - kobeya 10y ago
      If you mean the D-wave devices specifically, the kerfuffle is that the low-clockrate quantum device does not complete tasks any faster or cheaper than a comparably priced classical computer, and the open question as to whether they can ever be made to operate faster. That's why there's only research labs buying them. But the device does work.

kale 10y ago

I'm not an expert in the field, but I do annealing work on occasion (simulated annealing, which is kind of like copying polymer annealing). Simulated annealing is just an optimization. I use it for modelling human motion. You have the position and acceleration of each bone in the legs and feet. You start by deciding on a variable (say, reducing energy expenditure for gait), and then letting the algorithm alter variables and attempt to minimize a variable. So if quantum annealing is anything like simulated annealing, you aren't "solving" for a single, correct answer, but getting a solution that minimizes or maximizes an outcome faster than brute force. So a quantum computer could solve "What is the factorization of this huge number?", while quantum annealing could solve "Given these 30 different engine configurations, which combination of intake pressure, fuel flow rate, turbocharger performance curve, and engine timing would result in the best fuel efficiency?"

sp332 10y ago
The advantage of a quantum annealer is in cases where there is a large, narrow spike in the way of moving to a good solution. The quantum optimizer has a chance of "tunneling" through the spike to find a better solution. A classical version of simulated annealing would have to "climb" over the spike, or more likely just be stuck on the wrong side.
Ar-Curunir 10y ago
Optimisation and Search problems are not fundamentally different; one can usually translate a problem from one world to another. For instance, take your optimisation problem and rephrase it as: Here's a value of the fuel efficiency; find me a setting of the parameters that achieves a fuel efficiency better than that. It's now a search problem. To find the best fuel efficiency, just binary search over possible values of the efficiency. Where D-Wave differs is that you can only solve a particular kind of optimisation problem, and this kind of problem can't encode general computation. General quantum computers can solve general computation problems, not just the simulated annealing of D-Wave QC.

deleted 10y ago

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