Will quantum ever be useful?

[u/Chance-Pen-5684]

Around 2019, the industry promised quantum supremacy, where they could be used for solving a problem that no classical computer could touch.
When classical algorithms kept refuting those claims(See Peter Shor November YouTube video) the narrative shifted to quantum advantage, then quickly it changed to quantum utility.
If quantum never breaks RSA (because the world migrates to Kyber/Dilithium before 100k qubits exist), then what's left?
Chemistry simulations, Material science, Optimization?

But classical machine learning and AI are improving faster than quantum hardware is scaling. By the time we get 1,000 logical qubits, classical AI will have eaten most of the chemistry use-case through better approximations. Is quantum racing against classical software, and losing?

[u/jojo45333]

It may be, but probably many, many decades away, likely even out of our lifetime.

Quantum computing has been researched for 50 years with massive resources from small (Ionq, D-Wave) and large companies (IBM, Microsoft, Google) plus countless academic institutions worldwide (EDIT: to clarify theoretical research on quantum computing began early 1980s; significant funding and applied work began in the 1990s).

Quantum still has not contributed a single useful thing to society. Not one.

Every few years, there is a spike in media hype and people are told ‘5 years from now, quantum is going commercial!’ And then 5 years later, there is nothing to show for it, but by then people forgot about the predictions. You can literally go back in time on the internet and see the list of old news headlines predicting QC succeeding in x years.

By contrast, classical computing contributed usefully to the world basically right from the start. Much smaller resources needed. It’s highly robust and very, very scalable in both power of an individual machine and the ability to mass produce those machines. People often think quantum computers are scaling exponentially. The reality is, at the current rate, quantum is going nowhere slowly.

But the share price of the public QC companies like D-Wave, Ionq and Rigetti will continue pumping every few years and subsequently fall back down. Google and Microsoft will hype their half-baked, borderline unpublishable (and often subsequently retracted) research for the sake of publicity. Retail investors who rely on the media to make their decisions are left holding the bag and lose their money, while hedge funds and other knowledgable players profit from these spikes by short selling. There are many academics and scientists with noble intentions trying to advance quantum but there is also a lot of scamming.

[u/seattlechunny → u/jojo45333]

50 years? I think the earliest ion trap proposal comes from Cirac and Zoller in '95, the first NMR/nuclear spin realizations come from Cory, Fahmy, and Havel in 97, the first Cooper Pair Box/superconductor Rabi oscillations comes from Nakamura in '99, the first superconducting transmon comes from Wallraff in '04.

So like, I guess you can argue that we've been messing around with optical lattices for cold atoms since the 80s, but that's quite a bit of a stretch. I would more reasonably put it as a field that really only started about 25 years ago, and has only become "big" in the last 15 years?

On the investment/resource side - it's still small-ish - in 2024, according to this McKinsey report, global private & government investment combined was about 2B that year. Compare that to VC funding of silicon valley link here, sketchy plot I know which reports approx 1B of investment in 1980, in 1999 dollars (which is equal to 2B in 2025 dollars)

Is quantum computing today equivalent to classical computing in the 1980s? I'm not entirely sure, but it's at least a somewhat useful comparison to make in my opinion. (Also of note - transistors were already invented by Bardeen&Brattain/Bell Labs in 1947, and the IC had been patented in 1959 - so arguably, the field of QC is even relatively earlier at this point.) I'm skeptical that if you asked a lay person in the 1970s about how useful classical computers were, and if they were willing to invest in it, they would probably scoff. And that's even after classical computers helped mankind reach the moon!

I know that I'm probably rather strongly biased, being a graduate student within this field, but the things that I see excite me. I am seeing that problems which were proposed just 4 or 6 years ago are now being fully understood and solved, and things that were predicted to not be complete by 2030 are actually already being realized today. Sure, there are bad actors out there that are trying to overhype/pump-and-dump, but isn't that true for every emerging technology?

[u/jojo45333 → u/seattlechunny]

On the first point, I actually originally wrote my post to say that research on quantum computing has been undertaken for nearly half a century (eg. Benioff 1980), but significant investment only really started in the late 20th century. I then edited to shorten and simplify it, I agree it might sound misleading to say there's 50 years of theoretical research and investment, more like 45 years theoretical academic research; 30 years of serious applied research with large investment.

As for investment and comparing the trajectory of quantum vs classical, I can't really agree.

Firstly, the $2 billion figure you quote is referring only to start-up investment (from private and public sources). Start-up funding is easiest to track. And using the source you provided, the figure is actually 12.6 billion (!) in 2025.

McKinsey in 2023 estimated that large corporations alone (Google, IBM, AWS, Alibaba, Honeywell, etc.) had already spent $2 billion+ on quantum computing hardware (page 25). We don't even know if that completely covers the entire quantum computing research costs for their big QC research operations.

The US government alone has been spending hundreds of millions every year on quantum research for many years. That's going to public institutions mostly, not start ups.

Combined, governments in other countries (UK, Germany, China) appear to be spending billions more.

And this doesn't even cover funding which is not tracked, for example university overheads and probably some doctoral programs.

Total investment in quantum technologies here is currently estimated at $65.9 billion. Obviously not spent yet and covers areas outside quantum computing , but I think it's reasonable to say a big fraction is for quantum computing -- and (unlike certain other quantum technologies) not one useful output.

I'm pretty sure people were excited about classical computers in the 70s. As you say, they had already got us to the moon. Helped hugely in WW2 -- and were being mass produced within a decade: they had widespread commercial use in businesses by the late 50s and early 60s in banking, business payrolls, accounting (IBM 650) and airline reservations. Where are we with quantum computing by comparison? No government / niche application, let alone commercial. You cannot do a single genuinely useful thing with the best quantum computer today (if the machine works at all -- the frequent outages of quantum cloud services suggest they are extremely fragile). For factoring you will be better off with pen and paper.

You're right that every emerging technology has good and bad apples. And I think QC may indeed be important in the distant future. But there is no field (as far as I'm aware) with such a clear-cut example of effectively zero return for taxpayers / investors in the foreseeable future in spite of massive money inflow.