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Comment by fsh | Hacker News Reader

My current favorite cargo cult is the quantum computing scene. No practical quantum computer exists, and nobody has a realistic concept for building one. Yet, there are dozens of startups and research groups developing quantum algorithms, quantum cloud computing solutions, etc. They seem to believe that blindly copying what silicon valley did must surely lead to success. What they are missing (or are refusing to accept) is that silicon valley was only successful because they had useful computers from the very beginning. In Germany, the cargo cult was even enshrined in the names of two research clusters ("Munich Quantum Valley" and "Quantum Valley Lower Saxony").

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I work adjacent to this field, and I largely agree when it comes to the software side of things. With some notable exceptions, a lot of pure-play "quantum software" companies are premature optimizations to a field who's hardware can best be described as physics experiments with a Python API. Many of these places are pivoting to "AI" applications, which is simply them putting their mouths where the money is. If a "quantum winter" happens, many of these places will be the first to go.

I think this is partially a symptom of cargo culting the SV model, like you suggested, along with the much more fundamental reason that software has a very low barrier to entry. Hardware is hard, but it's really the most impactful investment to make in quantum tech at this early stage because of the spin-off applications in sensing, timing and networking.

> No practical quantum computer exists, and nobody has a realistic concept for building one.

Can you expand on that? I'm not involved in the field, but there certainly exist many low qbit machines with varying technologies around the world that can already be used for calculations. Yes, they're nowhere near big enough to be useful yet, but qbit counts in the biggest machines are multiplying every year similar to Moore's law, so that seems to be just a matter of time.

> qbit counts in the biggest machines are multiplying every year similar to Moore's law, so that seems to be just a matter of time.

That's pretty much my take on it too, just because it's pretty limited right now there appears to be healthy growth in qbit counts which would suggest a more usable quantum computer is mostly a matter of time and further research.

It doesn't matter how many qubits you have if those qubits are too noisy to do anything with. Noise is the ultimate limit when trying to get a useful signal out of something. Noise is how the universe stops us from knowing everything about everything.

The big "if" in quantum computing is in our ability to engineer error correction and fault tolerance. Implementing fault tolerance requires a physical qubit overhead of 10-10,000 qubits per logical qubit, depending on the technology, base error rate and whose analysis you look at.

It's not entirely accurate to say nobody knows how to do this. The theory of quantum error-correction has been rigorously developed since the 1990s, and experimental implementations have shown that improved fidelity is possible with known error-correction schemes. I think we'll know definitively within the next 3-5 years how hard it will be to engineer fault tolerance, and workable solutions will emerge from those findings.

Increasing the number of qubits doesn't help unless the gate fidelities and coherence times also improve. Otherwise, the system quickly becomes a very expensive random number generator. In transmon qubit systems, I haven't seen much progress in these metrics over the last couple of years. IBM keep adding more qubits to their chips, but they don't seem to be able to actually use them.

After almost thirty years of development, ion traps have now reached a few ten qubits with reasonable fidelities. However, this requires shuttling the ions between trapping zones which is enormously slow (many milliseconds per gate). And scaling this to hundreds of thousands of qubits is a completely open question (none of the current techniques will work).

> Can you expand on that? I'm not involved in the field, but there certainly exist many low qbit machines with varying technologies around the world that can already be used for calculations. Yes, they're nowhere near big enough to be useful yet, but qbit counts in the biggest machines are multiplying every year similar to Moore's law, so that seems to be just a matter of time.

I'll believe it when I see it. Yes, machines exist, but so far I have not seen one single convincing application that makes it better than a classical computer. Not saying it can't be done, but for all the hype around quantum computers, so far the results are dismal. (And I used to work in a relevant field.)

> qbit counts in the biggest machines are multiplying every year similar to Moore's law

2001: Shor's algorithm was demonstrated by a group at IBM, who factored 15 into 3 × 5

2012: factorization of 21 was achieved

2019: an attempt was made to factor the number 35, but the algorithm failed because of accumulating errors

https://en.wikipedia.org/wiki/Shor%27s_algorithm

You might fint twinkle/twirl interesting - it's prime factorization via optoelectronics

https://en.m.wikipedia.org/wiki/TWIRL

I think this post, like yours is simply forgetting that start-up culture isn't some immutable meritocracy of free market behaviour with these odd abberations of irrational behaviour. The whole thing is built off irrational behaviour, because becoming a "successful" startup is all about hunting VC funding.

Look at Uber for instance. Aside from one blip in 2018, it has never had a single year of profitability. Yet it receives year after year of VC funding and investments because surely any day now they have to turn a profit, right? All these people couldn't be wrong...right? I mean this is the revolutionary business that was a mArKeT DiSruPtOr and deregulated entire vast swaths of industries to do it, so surely their success will materialize "any day now" into profit. Afterall, its the most free-market principles-based business right?? It overthrew the tyrannical state-regulated taxi industry! It HAS to be more efficient and better! Except it isn't.

Quantum computing isn't a "cargo cult" of VC startup business models, its simply another VC startup business models like all others hunting for sustainability through venture capital funding.

Could you also be describing George Boole's wasted efforts in algebra?

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