AWS can tell us what it will cost
Or what it's useful for, but not both at the same time.
"It's very early days in quantum computing," Simone Severini, director of Quantum Computing at AWS tells The Reg. The quantum computers built so far have not shown yet to be impactful in business problems AWS does have a quantum computing service, called Amazon Braket, with a choice of five different brands of hardware, …
The perfect quantum computer has all the answers.
Until you look.
I think that Deep Thought was such a perfect quantum computer and then they looked, after 7.5 Myear. The wave functions collapsed and the final answer was 42.
Lessons learned: Perfect quantum computers have all the answers. You can just never ever look at any answer or all the other answers will vanish instantly (and you will be stuck with six times nine).
The perfect quantum computer has all the answers.
Uh, no, no it does not. What in the world are you on about?
Any sufficiently powerful formal system can express undecidable propositions. In fact, the vast majority of the propositions it can express are undecidable, per Chaitin's proof of irreducible truths.
In the physical realm, there are questions which run into essential physical limits, such as Heisenberg uncertainty.
No quantum computer of any sort, regardless of "perfection" (whatever that might mean in this context), contains the answers to such questions.
""Because the quantum computers built so far have not shown yet to be impactful in business problems," says Severini. "The hardware will not bring any advantage at the moment. But the trajectory of quantum computing will be that at some point, for certain specific applications, for certain specific problems, [they are] much much faster than any other type of computer we can actually build ..."
ENGLISH TRANSLATION: We haven't got the slightest idea what quantum computing is or what, if anything, it could be good for, but there's no way this Quantum Computing ship is sailing without AWS.
We know a great deal about what GQC is, and we know a number of things it could be good for, if the scaling and error-correction problems can be solved in an economical manner. It could be quite useful for certain types of physical simulations, for example.
People whinge when the Reg prints stories about QC enthusiasts making ridiculous claims, but they carry on just as much when it prints an interview with someone who has sensible things to say on the subject.
I suspect the only way they're going to be impactful at the moment is if someone drops one on you.
I'm skeptical of what seems to be a very sophisticated form of analog computing (the answer's in the noise, you just have to design a filter to pick it out) but at the same time looking at early digital computers built around valve 'logic' and mercury delay lines its actually a bit of a miracle that those things worked (doubly so if you remember that there was nothing 'before' to compare it to).
Come to think of it there was only a decade or so when computers were 'tangible' -- a Von Neumann architecture implemented in discrete logic or small scale logic ICs. We have to take it on faith (and for granted) that today's complex parts work -- they certainly seem to but the more you know about what they are and how they're designed and made the more it feels like a form of Black Magic.
what seems to be a very sophisticated form of analog computing
All physical computers are "very sophisticated form[s] of analog computing" when you get down to the metal. That aside, your description really does not apply to general QC. (It does to things like D-Wave's adiabatic machines, but those aren't general QC and are irrelevant here, and arguably everywhere else.)
If you look at algorithms in BQP, you'll see they are quite definitely discrete. They can be implemented just fine on conventional digital computers; they just don't have any quantum advantage there.
We already have working candidates for quantum advantage, so it's quite possible we will eventually have working general-QC systems which can solve a relatively small set of problems someone actually cares about, but which are intractable for conventional computers. Though what we're closest to right now, from the papers I've read, are solving problems mostly of interest to people trying to build QC systems. Still, things like (small but still intractable) particle-physics simulations aren't out of the question within a reasonable timeline.
That said, I am dubious about the economics of general QC for anything other than some fairly narrow primary-research projects. At this point, from what I've read, I don't have a lot of hope for commercially-viable systems for the sorts of business problems which could benefit from quantum advantage. By and large conventional asymmetric cryptography has little to worry about, for example; it just won't be practical to use Shor's algorithm to break RSA or ECC keys in bulk. (Specific high-value targets might eventually be vulnerable, and there's good reason to research and standardize on post-quantum cryptography anyway. Plus that's nearly a fait accompli at this point, and we've learned a lot of interesting things about codes and lattice problems and the like along the way.)