That's still many times faster than you'd get conventionally, so it's a reasonable trade off.
But it doesn't address the possibility that you can't entangle enough qubits to begin with, or keep them stable long enough to actually perform the calculations, which is where the error correction stuff comes in. I don't know enough about the challenges there to comment on how many you'd need (though 1000:1 seems high to my naive intuition, i'd guess maybe 10-100 for magnitude myself).
newbie question : are they naturally instable (so we won't fix that) or is it just because we don't master them well enough right now (and we'll fix them "soon") ?
However, with the right kind of quantum computer or quantum simulator, you could construct a system of qubits that is described by the exact same Hamiltonian. That way, the quantum state of your qubits and your original system would behave in exactly the same way. Then, you just let the qubits evolve in time and read out the system's state at the end. Do that a bunch of times and you'll see an average picture of what the original system you're modelling (protein or something) would do.
So to recap - we can get around the difficult compute bottleneck caused by the desire to perform high-fidelity physics simulations by creating a system that follows the same rules and which we can probe much more easily.
Your question doesn't make sense. Many (most) things in nature are incredibly hard to model correctly. Just because they happen doesn't make it easy to quantify usefully.
For other calculations you might need error correction, but this leads to nowhere with current technology. What the Chinese did was groundbreaking.
I know virtually nothing about quantum computing, so can you give some examples? Whenever I've asked anyone who seemed to know anything about the field, all they can come up with is weather forecasting and simulating nuclear explosions. Not exactly "general use," as you put it.
In the back of my mind, I know that quantum computing is a big deal, and we're in ENIAC days with it. But I don't have a good understanding of where it goes or why.
Many classical algorithms, which run in ~O(poly(n)) can have an 'equivalent' quantum algorithm in ~O(log(n)) - an exponential speedup. There is still debate as to how the complexity class of problems which are efficient on a quantum computer (BQP) relate to other complexity classes. Its suspected P lies entirely within BQP.
However, at least initially, I think quantum computers will be a specialized piece of equipment. Classical computing is pretty good for your average person. Quantum computers will be used for more heavy compute tasks.
It's actually known that BQP contains P[1]. It also contains BPP. What's not known is the relationship between BQP and NP (most experts suspect there's no containment in either direction).
[1] See this for an easy proof: https://people.eecs.berkeley.edu/~vazirani/f04quantum/notes/...
Even software that is supposed to be useful is so terribly slow. Computers are between 2 and 4 orders of magnitude faster than programmers today experientially believe they are, because today’s culture of programming has rotted so thoroughly. Do you really need a quantum computer when 3 orders of magnitude are just sitting there on the table waiting to be picked up?
Three orders of magnitude speedup is a constant factor. Quantum computers provide between sqrt(n) and log(n) speedup depending on the problem - for example, biochemistry simulation for improved drug designs and such. That seems worthwhile.
So if I decide to use the device that I have bought and invested in, to "rant" about something (to connect to other people through it, essentially), or even just connect to my loved ones sending "meaningless" information (as many I'm sure would call it), or if I choose to use it for anything else, who is to say that it's "wasting my life"? You? Why do you decide what is wasteful and what is not? Maybe all those people want to do those things?
You can't say that this technology is wasted or is not used properly without also implicitly assuming moral and philosophical authority about what people should choose and not to choose with their time and other resources, including the money used to buy such devices and resources spend on developing them. Why do you assume that you can be such an authority?
Of course, looking at this in another way, you definitely have the ultimate authority in this area in this one regard: where it applies to your own life. Which I guess is another way of saying that what you wrote says more about your outlook on life than on the underlying technology and its social ramifications.
The original author used his "objective measure of excellence" as an argument for not developing quantum computing technologies to be used in personal devices. In this specific instance, in this practical regard (even though it's probably 50 years too early for this question) - I argue that yes, the position of personal freedom (to use quantum computing in cell phones, exaggeratedly) does indeed trump the other position which is to actively exclude quantum computing from phones for the vague fear that people might waste their lives on it, by failing to fit into some objective measure of excellence.
You're certainly free to find the relevant response to that intellectually boring. But it's quite a leap from OP's totalizing statement of despair to implicitly fill in that ellipsis with "allusion to human well being."
I'd like to be generous in my reading, but I don't see any room in there for a discussion of "heavy" vs healthy device use.
And I agree that it's disheartening to watch how horribly we use these incredible tools. But thankfully as programmers we're in a position to design these tools to offset the worst parts of humanity.
And one field in which more powerful computers will be needed soon is deep learning. It appears that progress is beginning to stall, as larger networks are necessary. Better tools for distributed computing will make up the difference in the short term, but the current infrastructure appears to be insufficient for general intelligence.
"In 50 years, every street in London will be buried under nine feet of manure."
I totally agree with your first paragraph, though.
A lot of optimizations left on the table have nothing to do with manual memory management, and have everything to do with "eh, let's just the query the database again, that'll shave a day off the schedule".
Answer that and I get the feeling you’ll understand why your current thinking is so misguided.
> because the trend in language design for 25 years has been to make slow languages
No one sets out to make a language to make them slow. The trend is to make higher level languages. Do you really think that there is no reason for it besides novelty and coolness factor?
Can I say "pretty much all of Linux userspace"? Or Java VM? Or Gnome?
He's instead saying that it's very much possible to build a language with a similar level of abstraction/ergonomics to say, Java, or Python, or C#, or whatever but with similar performance characteristics to a lower level language like C. And we are starting to see this - there are languages like Rust or D which are (at least to my eyes) much less arduous and foot-gun prone than languages like C or C++ while having similar (or better) performance.
Of course there's also Jai, but I think we should remain unbiased here :P
As an aside though - I think some of those orders of magnitude of performance gains could be had by just writing better code in your existing high level languages. (At least in my experience with enterprise software dev).
So far, reality seems to confirm my intuition.
Technology doesn't make people better. It lets people do better things if they have the desire to do so. It also must enable them to do worse things if they have the desire to do so. You can not have one without the other. And on the balance things have historically gotten better so there's not too much reason to be worried about the fact most people just use global communication to bicker. They won't be remembered. Those who are, however, wouldn't have been possible otherwise.
As for where quantum computing factors into this, I don't have the slightest clue.
"They won't be remembered."
-otakucode
As Timothy Snyder notes when discussing the internet, the introduction of the printing press divided Western Christianity thereby causing a century and a half of religious wars in which a third of the population was killed. And later it gave us the Enlightenment and educated society.