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D-Wave Quantum Computing Solution Raises More Questions
benonemusic writes "The commercially available D-Wave computer has demonstrated its ability to perform increasingly complex tasks. But is it a real quantum computer? A new round of research continues the debate over how much its calculations owe to exotic quantum-physics phenomena. 'One side argues there is too much noise in the D-Wave system, which prevents consistent entanglement. But in an adiabatic device, certain types of entanglement are not as vital as they are in the traditional model of a quantum computer. Some researchers are attempting to solve this conundrum by proving the presence or absence of entanglement. If they show entanglement is absent, that would be the end of the discussion. On the other hand, even if some of D-Wave's qubits are entangled, this doesn't mean the device is taking advantage of it. Another way to prove D-Wave's quantumness would be to confirm it is indeed performing quantum, and not classical, annealing. Lidar has published work to this effect, but that triggered opposition, and then a counter-point. The debate continues.'"
how do you show the presence of entanglement without disturbing it?
Can someone explain to me how this chip could be calculating anything unless the quantum part was working?
Isn't it like a car that has an electric motor or a gas one, but not both? How can they be confused which engine is running? Who builds a backup normal processor then what, it fills in if the quantum one doesn't work right, and they have no way to tell if this backup kicked in?
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
There should be plenty of problems a quantum computer could solve in polynomial time that would take classic computers eons to solve. Start solving those problems and it's a quantum computer. Simple as that.
When the copyright term is "forever minus a day", live every day like it's the last.
This situation is completely reasonable give the current state of the art in quantum computing.
Making accusations of "marketing hype" and unethical behavior are irrelevant. Whatever it's doing, it's not digital computing. Even if it turns out to be classical physics, it is still advancing the state of the art in non-digital computing.
No matter how DWave does in the future, quantum computing is still going to happen in the near term. Dwave is not going to change that under any circumstances.
Getting bent out of shape over this is a waste of effort. Even the experts are not in agreement. This is how progress occurs at the cutting edge.
Why is Snark Required?
Hasn't the benchmarks already placed it above pretty much any computer in the tasks it can do within its full size?
My understanding was that the benchmarks - at least the one that was quoted as showing a "3600x speedup" - weren't even comparing the same thing: the D-Wave computer was running the quantum adiabatic annealing method, which is the only way it can be programmed, while the conventional CPU was running an exact solver. The latter is expected to be vastly less efficient (but more precise). When a group of computer scientists came up with an annealing method to solve the same problem on a conventional CPU, they ended up with something just as fast as the D-Wave system.
Answer: It's *SO* quantum that even the issue of whether or not it's quantum exists in a superposition of states!
Measure correlations between the two systems. If you have entangled, oppositely polarized photons and you simultaneously pass them through aligned polarizers then one will always pass through the filter and one will always fail. It is impossible to recreate this in any classical system without communication between the photons.
If you can perform the same type of measurement with entangled qbits in a manner where it is physically impossible for them to communicate (e.g. make the two measurements simultaneously) you can confirm their quantum nature.
... I got the impression that he is not overtly concerned about this ongoing controversy, although he did mention he prepared another paper to demonstrate entanglement on the chip.
But his focus is clearly on tackling hard tasks with immediate applicability (for instance in deep learning).
Because *IF* it can be developed, someone will eventually develop it, and probably sooner rather than later. Technological advances depend less on creative genius and more on previous technological advances. It's like how radar was developed simultaneously by about a half-dozen different nations, but they were all trying to keep this supposed strategic advantage secret from one another. It's not that it was a coincidence, but rather that the time was right, and the pieces were all in place.
Isn't it better to develop a quantum computer first, so that you know to stop using vulnerable forms of cryptography? Anything else is just sticking your head in the sand. Failing to develop it yourself will not stop the other guy from doing it.
The benchmark did indeed not demonstrate a quantum speed-up, but it in fairness to D-Wave this was a test designed based on the customers requirements i.e. for them acing this benchmark was good enough to justify investing in this technology.
My understanding is that the algorithm that was comparatively fast on a classical computer was hand optimized by a graduate student, it was not a generic annealing algorithm solver.
But the paper on this effort of 'beating' D-Wave on a classical machine is yet to be published, so this is all from blog hearsay.
Could you elaborate a bit on this? I had the impression that D-Wave's users had to map their problem to fit what D-Wave computes, not the other way around. That would make comparisons with a specialized software solver appropriate, wouldn't it?
The blog post in question also includes a link to the source code of the specialized solver (Prog-QAP), and others have confirmed that it produces the same results as CPLEX, the general solver that D-Wave beat.
CPLEX is indeed slower than D-Wave, though newer versions have brought the factor down from 3600x to 14x. But again, CPLEX is a general solver, while D-wave is specialized hardware. The specialized software solver Prog-QAP is *much* faster than CPLEX, and gets a 12000x speedup over D-Wave when running on a single core.
But all of that is a bit old, and it may be that D-Wave has produced more impressive results after that. I hope D-Wave's approach results in something able to beat classical computers, even if it doesn't lead to a general quantum computer. But I really dislike all the secrecy they employed - that is not how science is supposed to work. The fraud speculations they have had to endure are entierly self-inflicted due to this secrecy.