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.'"

Comments

Sounds like a scam, quite frankly

[Impy the Impiuos Imp]

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?

Re:Sounds like a scam, quite frankly

[HuguesT]

Theoretical Quantum computer using entanglement to perform their calculations make no claim to solve NP-hard problems. They can only solve some very specific class of problems, that are well identified but are still interesting. Integer factorisation is one of them, but factorisation is not thought to be in NP-complete, although we are not certain at this stage.

There is an old article in PNAS that says that adiabatic quantum computers are theoretically no better than classical computers at solving NP-hard problems. So even if D-Wave had a truly working adiabatic quantum computer, it is not clear that it would perform orders of magnitudes better than what we have now.

Anyway all of this is very interesting to watch, but the fact that D-Wave is so secretive is not very compatible with progress in the field.

Just do it.

[CanEHdian]

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.

DWave itself is in an indeterminate quatum state

[Required Snark]

Consider the hypothesis that the DWave machine is a superposition of classical and quantum computing. By some observations it is classical, by others quantum. As some point a measurement will be preformed on the machine, and it's state will resolve into either a classical physics computing device or a quantum physics computing device.

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.

Re:Hasn't the benchmarks put it above anything?

[quax]

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.

Re:Hasn't the benchmarks put it above anything?

[amaurea]

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.