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>The D-wave device does not have a superposition of states, rather it is tracking a single classical state I'm going to need a citation on that. Even if only

>The D-wave device does not have a superposition of states, rather it is tracking a single classical state I'm going to need a citation on that. Even if only some small fraction of the qubits in the 2^2000 search space are fully entangled, that's still a massive improvement over the current state of the art using conventional computers because of how absolutely huge the space is.

johncolanduoni 10y ago
Not if the entanglement is partitioned into very small groups of qubits. That's the only thing we have even circumstantial evidence of, and it doesn't appear to gain us much over classical computers. This is especially bad for the "it'll be better with more qubits" hypothesis D-Wave is chasing, since everything we know about quantum control suggests that if you can't solve this problem with a 1000-qubit system, doing it with a 2000-qubit system is going to be even harder. We're still waiting for one problem, no matter how arbitrary, where the D-Wave beats basic consumer computers, let alone a few million dollars worth of computing power. And if D-Wave (or anyone else) had found one for their 2000-qubit computer, it would be in this press release. So no, any gain in performance form the D-Wave hardware is still in the "theoretical but without any theoretical backing" stage.
- logicallee 10y ago
  >We're still waiting for one problem, no matter how arbitrary, where the D-Wave beats basic consumer computers This is like saying that NASA has never gone to space, because there is not ONE thing they have EVER done in space, no matter how arbitrary, (including going to the moon) that I care about more than literature. Let's look at the parts of my analogy: NASA has not gone to space BECAUSE it is not better than something irrelevant. DWAVE does not have a quantum computer BECAUSE it is not better than something irrelevant. What on Earth do classical computers have to do with whether DWAVE is using quantum effects? This is very irrelevant. I can't believe so many people use this to "prove" that it's not a quantum computer. This is a complete and utter non sequitur. This is very basic logic. It's like saying that until the minute a machine beat Kasparov at chess, computers couldn't play chess. In a very narrow sense of cheating, sure, a computer could fake playing chess if a person is hidden and playing for the computer. Maybe the comouter isn't even powered on. Likewise, in a narrow sense a classical computer could be hidden in the DWAVE's cabinet and producing the output with a python script. Maybe the DWAVE isn't even powered on. (and has a cheater inside, a macbook.) But short of this scenario it is a completely inappropriate point to make. It doesn't say anything about how dwave works. -> Are you accusing them of not even powering it on and hiding a macbook in the case, which produces all its results? (if not, how is your contention different.)
  - gaze 10y ago
    Well the burden to prove they've made a quantum computer is on them, no?
    - logicallee 10y ago
      But when you raise the bar to "better than a desktop PC" it is like going from "well the burden is on chess computers to prove their machine really plays chess" to "the burden is on chess computers to prove they're better than humans (and it's not real until they do.)". That is too high a bar. My only objection is on this suggestion - that they have to find something it's already better at than a desktop PC (with literally billions of transistors). I quoted the part I objected to.
      - gaze 10y ago
        But scaling laws should predict that you should need many, many more transistors than qubits to beat a gate quantum computer. For an adiabatic quantum computer something similar should hold.
  - johncolanduoni 10y ago
    > I can't believe so many people use this to "prove" that it's not a quantum computer. This is a complete and utter non sequitur. That's not why I'm saying it's probably not a quantum computer. It's not a quantum computer because in depth analysis of its behavior has consistently shown that above the ~20 qubit scale it's better modeled by a classical explanation than a quantum one. We only really have evidence of entanglement at the 8 qubit level[1] so far. The fact that the processing power is abysmal just makes the hype even more ridiculous. The point of that fact is that it's not like the EmDrive, where it's doing something we can't yet explain under the assumption that nothing interesting is going on. If it weren't for the fact we've looked inside, it could be running a basic Intel CPU for all we know. There's no smoke at any level, so it's nonsensical to give D-Wave a pass and think they've got some fire. [1]: https://arxiv.org/abs/1506.03539 https://arxiv.org/abs/1506.03539

johncolanduoni 10y ago

Not if the entanglement is partitioned into very small groups of qubits. That's the only thing we have even circumstantial evidence of, and it doesn't appear to gain us much over classical computers. This is especially bad for the "it'll be better with more qubits" hypothesis D-Wave is chasing, since everything we know about quantum control suggests that if you can't solve this problem with a 1000-qubit system, doing it with a 2000-qubit system is going to be even harder. We're still waiting for one problem, no matter how arbitrary, where the D-Wave beats basic consumer computers, let alone a few million dollars worth of computing power. And if D-Wave (or anyone else) had found one for their 2000-qubit computer, it would be in this press release. So no, any gain in performance form the D-Wave hardware is still in the "theoretical but without any theoretical backing" stage.

logicallee 10y ago
>We're still waiting for one problem, no matter how arbitrary, where the D-Wave beats basic consumer computers This is like saying that NASA has never gone to space, because there is not ONE thing they have EVER done in space, no matter how arbitrary, (including going to the moon) that I care about more than literature. Let's look at the parts of my analogy: NASA has not gone to space BECAUSE it is not better than something irrelevant. DWAVE does not have a quantum computer BECAUSE it is not better than something irrelevant. What on Earth do classical computers have to do with whether DWAVE is using quantum effects? This is very irrelevant. I can't believe so many people use this to "prove" that it's not a quantum computer. This is a complete and utter non sequitur. This is very basic logic. It's like saying that until the minute a machine beat Kasparov at chess, computers couldn't play chess. In a very narrow sense of cheating, sure, a computer could fake playing chess if a person is hidden and playing for the computer. Maybe the comouter isn't even powered on. Likewise, in a narrow sense a classical computer could be hidden in the DWAVE's cabinet and producing the output with a python script. Maybe the DWAVE isn't even powered on. (and has a cheater inside, a macbook.) But short of this scenario it is a completely inappropriate point to make. It doesn't say anything about how dwave works. -> Are you accusing them of not even powering it on and hiding a macbook in the case, which produces all its results? (if not, how is your contention different.)
- gaze 10y ago
  Well the burden to prove they've made a quantum computer is on them, no?
  - logicallee 10y ago
    But when you raise the bar to "better than a desktop PC" it is like going from "well the burden is on chess computers to prove their machine really plays chess" to "the burden is on chess computers to prove they're better than humans (and it's not real until they do.)". That is too high a bar. My only objection is on this suggestion - that they have to find something it's already better at than a desktop PC (with literally billions of transistors). I quoted the part I objected to.
    - gaze 10y ago
      But scaling laws should predict that you should need many, many more transistors than qubits to beat a gate quantum computer. For an adiabatic quantum computer something similar should hold.
- johncolanduoni 10y ago
  > I can't believe so many people use this to "prove" that it's not a quantum computer. This is a complete and utter non sequitur. That's not why I'm saying it's probably not a quantum computer. It's not a quantum computer because in depth analysis of its behavior has consistently shown that above the ~20 qubit scale it's better modeled by a classical explanation than a quantum one. We only really have evidence of entanglement at the 8 qubit level[1] so far. The fact that the processing power is abysmal just makes the hype even more ridiculous. The point of that fact is that it's not like the EmDrive, where it's doing something we can't yet explain under the assumption that nothing interesting is going on. If it weren't for the fact we've looked inside, it could be running a basic Intel CPU for all we know. There's no smoke at any level, so it's nonsensical to give D-Wave a pass and think they've got some fire. [1]: https://arxiv.org/abs/1506.03539 https://arxiv.org/abs/1506.03539