The need for quantum computers remains small • Hacker News Board

Re: The need for quantum computers remains small

#41

Post by exmadscientist » Sat, Jul 23, 2022, 7:30 AM UTC

femto wrote: post #29

amelius wrote: post #10

Earlier quoted context omitted.

Computational chemistry (e.g. protein folding) is one useful application.

Which leads onto computational medicine. The advent of SPICE [1] meant that with the right models electrical engineers could simulate complex electrical systems, do sensitivity analysis and make integrated circuits that had a high probability of working. Imagine a (quantum) simulator that can rapidly simulate all or part of the human body. The effects of medicines could be rapidly simulated, or the simulation could g…

Why do you believe a quantum computer can actually solve that problem? The whole point of the article is that quantum computers are not and can never be general-purpose computers. And something with as many inputs as "simulate the human body" seems like the exact opposite of what you can encode in qubits, evolve as a state vector, and usefully read out.

Re: The need for quantum computers remains small

#42

Post by sgt101 » Sat, Jul 23, 2022, 7:32 AM UTC

chasil wrote: post #14

tjr225 wrote: post #9

Earlier quoted context omitted.

It seems that nobody on the planet is able to invent their own quantum computer.

Actually, a 65-qubit quantum computer has been created. "IBM's current largest quantum computer, revealed this month, contains 65 qubits." https://www.science.org/content/article/ibm-promises-1000-qu...

There is a big difference between a practical QC and the QC we have now. 65bits isn't practical for any known real problem but ask also how long it takes to boot it, how many cycles it can execute per run and how many runs it can do per day (or week).

These thing are not like your laptop, they are more like particle accelerators.

Re: The need for quantum computers remains small

#43

Post by mtlmtlmtlmtl » Sat, Jul 23, 2022, 7:50 AM UTC

codeflo wrote: post #36

mtlmtlmtlmtl wrote: post #33

Earlier quoted context omitted.

I believe his point was more that the quantum measurement could very well end up costing enough time to be an issue. He didn't to into a great amount of detailed as it was mentioned more as a tangent.

The sceptic arguments I read focus on accidental decoherence during the computation. If that goes well, and classical computers only "catch up" during measurement, wouldn't this mean that the time cost of measurement has to scale super-polynomially? Is that plausible?

I got tired of speaking on behalf of a vague memory of Stephen Wolfram speaking that I just looked up the transcript.

6 SW: Yeah, I think… I think it’s not going to be true[that QC gives a speedup], that’s my guess. I think what’s going to happen is, if you take short algorithm for factoring, which is primarily a quantum Fourier transform, that Fourier transform is done beautifully quickly because there are all these threads that are running in parallel. The problem is, every thread is somewhere in a different place in branchial space, that thread, that us observers, we have to corral all those things back together again in order to tell what actually happened, and that’s… So there’s a… Usually in quantum computing one just says, “and then there’s a measurement.”

1:26:49.0 SW: Now, in actuality, when you have an actual device, you have all kinds of issues in making that measurement, all kinds of… How quickly does it decohere, all these kinds of things. There are all these kinds of very practical experimental features, and I think people have generally said, given the formalism of quantum mechanics, it’s like, well, all this quantum stuff happens and then boom, we do a measurement, and the boom, we do a measurement is actually pretty difficult in practice with actual experiments, that people have said, but if we do these experiments well enough, it will become the mathematical idealization that von Neumann and others made about how measurement works, and I don’t think that’s going to be true. I mean, we’re not sure yet, but it seems likely that there will be no way to do… To sort of, if you’re honest about how the measurement works, the measurement takes effort.

Re: The need for quantum computers remains small

#44

Post by baby » Sat, Jul 23, 2022, 7:51 AM UTC

bowsamic wrote: post #30

LeegleechN wrote: post #26

He's not wrong about the narrow algorithmic use cases (so far), but he's completely missing the utility for simulation of quantum phenomena (chemistry, microbiology, materials science). That use case alone completely justifies investing into them even if you don't care about advancing science.

Yeah the problem is in the name and the marketing. People think it is meant to replace normal computers, but that is totally wrong. The simulation use cases as well as probing fundamental physics are far more immediate and exciting

And there’s all the crypto FUD that quantum computers will scale enough to break crypto algorithms

Re: The need for quantum computers remains small

#45

Post by feliyur » Sat, Jul 23, 2022, 8:28 AM UTC

From my limited understanding, a quantum computer performs computations over probability distributions, rather than over numerical values. Performing precise computations over probability distributions is a serious problem in many domains - physical simulations are just one. Another example is that could allow much more efficient and precise data fusion, and as a result - a leap in AI abilities, across domains where AI is used.

Re: The need for quantum computers remains small

#46

Post by pyinstallwoes » Sat, Jul 23, 2022, 8:30 AM UTC

zbobet2012 wrote: post #39

_8091149529 wrote: post #38

Earlier quoted context omitted.

What would be the example of an outstanding, reasonably-sized (even quantum computers of the future have finite resources) quantum simulation problem that is intractable today but would unlock some economic potential, if solved?

Drug molecule interactions, simulations for super conductors, etc. Etc.

So quantum computers are just computational statistics?

Re: The need for quantum computers remains small

#47

Post by pyinstallwoes » Sat, Jul 23, 2022, 8:31 AM UTC

johnebgd wrote: post #37

tho2u43234 wrote: post #35

That's probably because "real" quantum computing today can't even factor 4-bit numbers. The coherent-bits are really not scaling fast enough (and this is to be expected given their entanglement IMO) for anyone to really care other than snazzy startups scamming investors of their money.

Yeah, quantum computing is still basically experimental…

Experimental, non-physical, completely theoretical. Yep.

Re: The need for quantum computers remains small

#48

Post by pyinstallwoes » Sat, Jul 23, 2022, 8:32 AM UTC

soganess wrote: post #2

Barring the sky falling, our best bet for NP hard problems is approximate solutions that have provable lower bounds on approximation ratio. From that purview, a general heuristic for approximating combinatorial optimization problems would be a godsent. Even if algorithms like the QAOA do not improve(or tightly match) approximation ratios beyond that of a carefully crafted classical algorithm... A turn key algorithm o…

Kind of like how instead of modeling the entire economy and figuring out how to influence the behavior, you just identify a key parameter such as inflation or interest rates and modify that to affect every possible outcome.

Re: The need for quantum computers remains small

#49

Post by einpoklum » Sat, Jul 23, 2022, 8:40 AM UTC

reacweb wrote: post #23

jchw wrote: post #18

Earlier quoted context omitted.

You're only following the winners, but computer science has also had a lot of flops, too. Time will tell if quantum computers is one of those, but it sure isn't looking great so far.

At that time QL Sinclair was a loser. A good computer that never got programs. It was the computer of Lius Torwalds and the reason he had to write himself programs. Without QL Sinclair, we may never had Linux. At my work, I was present when the research on ASAS ( https://skybrary.aero/articles/airborne-separation-assurance... ) led to the idea of PMS ( https://www.eurocontrol.int/sites/default/files/2021-05/euro... )…

> we may never [have] had Linux.

Oh, come on. Linux was a clone of MINIX with a GPL license. If Linus had not written it, somebody else would have; and at worst (if that is worse), we would have all been running FreeBSD now.

Re: The need for quantum computers remains small

#50

Post by hnfong » Sat, Jul 23, 2022, 8:43 AM UTC

baby wrote: post #44

bowsamic wrote: post #30

Earlier quoted context omitted.

Yeah the problem is in the name and the marketing. People think it is meant to replace normal computers, but that is totally wrong. The simulation use cases as well as probing fundamental physics are far more immediate and exciting

And there’s all the crypto FUD that quantum computers will scale enough to break crypto algorithms

It hasn't happened yet or won't happen any time soon, but if there's a chance RSA is going to be broken I'd rather be aware of the possibility 10 years earlier than 10 days after...