It's not only early days in hardware, it's early days in practical applications as well: https://arxiv.org/abs/2511.09124
If we mean "we've have been working on this for almost 3 decades. That's a very long time to be working on something!". I agree.
If we mean "We just now only have a few logical qubits that outperform their physical counterparts and we'll need thousands of these logical qubits to run anything useful" then we are still in the early days.
id have assumed the holography has gotten more common and able to operate on bigger volumes
I have not seen any progress or breakthroughs in the QC field at all that are significant.
If the only goal for QC is to try to run Shor's algorithm or to "try to break the bitcoin blockchain" then it is worse than useless.
What are the real world use cases now, today? The only thing I see in the QC space, are QC stocks and funding paying for the employment of scientific experimentation, which isn't a real world application.
Do I have to wait 15 to 30 years for a series of real world changing breakthroughs that I can already do on a NVIDIA GPU card?
That doesn't exponential at all, in fact that sounds very very bearish.
There are no real world use cases today. The hardware is not advanced enough yet, but it's improving exponentially.
Quantum theory predicts that they will work given enough time. If they don't work, there is something about physics that we are missing.
The way to test out this theory is to try out an experiment to see if this is so. If this experiment fails, we'll have to figure out why theory predicted it but the experiment didn't deliver.
If "this experiment" is trying to build a machine, then failure doesn't give much evidence against the theory. Most machine-building failures are caused by insufficient hardware/engineering.
In the specific spot I commented, I guess you were just talking about the physics part? But the GP was talking about both physics and physical realization, so I thought you were also talking about the combination too.
Yes we can probably test the quantum theory. But verifying the physics isn't what this comment chain is really about. It's about working machines. With enough reliable qubits to do useful work.
On the engineering end, the question on if a large-scale quantum computer can be built is leaning to be "yes" so far. DARPA QBI https://www.darpa.mil/research/programs/quantum-benchmarking... was made to answer this question and 11 teams have made it to Stage B. Of course, only people who believe DARPA will trust this evidence, but that's all I have to go on.
On the application front, the jury is still out for applications that are not related to simulation or cryptography: https://arxiv.org/abs/2511.09124
Quantum theory doesn't predict that it's possible to build a large scale quantum computer. It merely says that a large scale quantum computer is consistent with theory.
Dyson spheres and space elevators are also consistent with quantum theory, but that doesn't mean that it's possible to build one.
Physical theories are subtractive, something that is consistent with the lowest levels of theory can still be ruled out by higher levels.
Quantum theory, like all physical theories, makes predictions. In this case, quantum theory predicts that if the physical error rate of qubits is below a threshold, then error correction can be used to increase the quality of a logical at arbitrarily high levels. This prediction can be false. We currently don't know all of the potential noise sources that will prevent us from building a quantum logic gate that is of similar quality as a classical logic gate.
Building thousands of these logical qubits is an engineering problem similar to Dyson spheres and space elevators. You're right that the lower levels of building 1 really good logical qubit doesn't mean that we can build thousands of them.
If our case, even the lower-levels haven't been validated. This is what I meant when I implied that the project of building a large-scale QC might teach us something new about physics.
Then invest accordingly, and later reinvest your winnings in a different direction.
Here's what's going on here: there's a way that people talk past each other, because they mean different things by the same words, because they ultimately have different cultures and values.
There's one kind of person (let's call them "technologists," but I'm sure there's a better word) who feels deeply and intuitively that the point of a technology is to Create Shareholder Value. There's another kind (let's call them "scientists") who feels deeply and intuitively that the point of a technology is to Evince That We Have Known The Mind Of God. I think that these two kinds of people have a hard time understanding one another. Sometimes they don't realize, as strange as it sounds, that the other exists.
There are many scientists who have been working on problems falling loosely under the umbrella of "quantum computing" for a few decades now. Most of them are not literally Building A Quantum Computer, or even trying to. Not exactly. For this reason it might be better to call the field "things you can do with coherent control of isolated quantum systems" than "quantum computing." There are many strange and wonderful things that you can see when you have good coherent control of isolated quantum systems. The scientists are largely interested in seeing those things, in order to Evince That We Have Known The Mind Of God. One sort of strange and wonderful thing, way down the line, is maybe factoring big numbers? The scientists honestly call that a "goal," because it would be strange and wonderful indeed. But it's not really the goal. The scientists don't really care about it for its own sake, and certainly not for the sake of Creating Shareholder Value. It's just one thing that would Evince That We Have Known The Mind Of God.
Incidentally, over those last couple of decades, we've gotten way better at coherent control of isolated quantum systems, and have, in many ways, succeeded at Evincing That We Have Known The Mind Of God again and again. We have made, and continue to make, amazing progress. One day we probably will factor large numbers. But that's not really the goal for the scientists.
On the other hand, there are "technologists" who hear about the goal of factoring large numbers, take this to be, in some sense, "the point" (that is, a proxy for Creating Shareholder Value), and expect it to happen in short order. They raise lots of money and promise a payout. They might act in very "commercial" ways, telling people what things are going to happen when, using an idiosyncratic, personal definition of truth. This is understood and expected in commercial situations. They and their creditors may be disappointed.
The trouble is that it's hard for people on the outside to tell the difference between the scientists and the technologists! This makes things confusing. On some level, this is a failure of science communication: laypeople hear about breakthroughs (from scientists), then don't see the promises of technologists immediately fulfilled, they get confused, and they start to think the scientists are lying. But they're not! They're different people.
Another thing that laypeople don't really know is that there are commercially-useful and near-commercially-useful technologies using coherent control of isolated quantum systems. They've come out of the same research program, but aren't strictly "quantum computing." I don't know why it's not more widely known that quantum sensors made out of qubits (usually a different kind of qubit than the kind used for computing applications!) are on the market today, and beat other sensors along a variety of axes.
This might sound like goalpost-moving, but I promise you it's not. If it sounds like goalpost-moving, it's because there are two different relevant groups of people you hadn't previously resolved!
1. Sam Altman: [tells a tall tale to raise 100 quintillion dollars]
2. Outside observer: "hey, these so-called AI researchers have been pulling the wool over our eyes! They've promised AGI for decades. Where's my robot maid?"
3. Researcher who's been making steady progress in a niche subfield of optimization algorithms at Nebraska State University for the last 20 years: "huh?"
its not necessarily time that real science and engineering takes, but resources.
there's lots of fast progress happening in areas that get a lot of resources invested into them, and much slower on areas that dont have financial champions. moving fast doesn't necessitate that something is a scam
In any case (and I don't think this bears on your point, it's just something I'd like to add), building a quantum computer is very unlike building a nuclear fission device. Echoing my other comments here, it's almost misleading to call it "building a quantum computer," as that puts people in mind of 'unlocking' some single discrete technology in a strategy game tech tree. It's not that at all; it's a huge umbrella of (in many cases) extremely sophisticated technologies. The Manhattan project, as complex and astonishing a feat as it was, was a little closer to the strategy-game vision of research in that way. There's a reason it was possible in 3-4 years in the 1940s!
- Intel can now do 2D which means a Surface code can be run on these devices: https://arxiv.org/abs/2412.14918
- HRL can now do 2D as well: https://arxiv.org/abs/2502.08861
- They are solving the wiring problem: https://www.nature.com/articles/s41565-023-01491-3
- Their interconnects are high fidelity: https://www.nature.com/articles/s41586-025-09827-w
Time for git to break all workflows by showing huge alerts if a server is using crypto not proven quantum-proof!
Basically anytime we send a signal across a large fiber optic cable we need to convert signal from light back to electricity and that requires some level of photonic computing. Its used at scale today. https://www.ebsco.com/research-starters/science/photonics
However I suspect that you mean photonic computing where a computer on chip device uses photons instead of electrons to communicate. In which case, as far as I know is still research phase.
giuliomagnifico•1mo ago
refulgentis•1mo ago