[sanxiyn]

The main point is that just as you can't ask for tiny nuclear explosion because nuclear physics just doesn't work that way, you also can't ask for factoring of 21 with Shor's algorithm. Quantum computing just doesn't work that way, sorry.

[Revanche1367]

The analogy between nuclear fission and quantum computing doesn’t really work. Fission was a relatively new physical phenomenon the Manhattan Project scientists were studying to turn it into a weapon of mass destruction on a scale that too had no precedent except in natural disasters. Quantum computing is a new technology that is supposed to make already effectively computable problems computable faster; it is ideally supposed to provide an increase in capacity, not capability. It should definitely be able to make tiny computations work before going for the bigger problems. That’s how all computing works, if it can’t solve simple problems, it’s never going to solve bigger ones. What you’re saying here essentially sounds like “there will be a magical event one day when quantum computing solves the biggest computing problems and we’ll all realize it works.”

I am not particularly invested either which way about the likelihood of quantum computing being a major breakthrough or not but this is seeming like yet one more area of computing research like crypto and LLMs which in recent years is increasingly being flooded by people on a hype train.

[mrguyorama]

>The main point is that just as you can't ask for tiny nuclear explosion because nuclear physics just doesn't work that way

You absolutely can, which is why Fermi did just that as part of the Manhattan project with the Chicago Pile 1, demonstrating the first self sustaining nuclear chain reaction.

In 1942.

Your analogy is broken.

[tgv]

That was not a tiny explosion, me thinks.

[sehansen]

Given that 15 has already been factored using Shor's algorithm on a real quantum computer, I think we can.

[sanxiyn]

No you really can't. Being able to factor 15 but not 21 with Shor's algorithm is normal. I know it sounds absurd, but it really is that way. Because factoring 21 is about 100x times harder than factoring 15.

See https://algassert.com/post/2500 for details.

[sehansen]

My point was that the comparison with nuclear explosions is wonky, since we (in the world of that analogy) already have seen a tiny nuclear explosion 15 years ago. And we kept being told that explosions 100 times larger are just around the corner, but explosions 25% larger are way too hard to expect.

I get that there's a lot of R&D going on to make larger quantum computers a thing and that there's been very definite progress, but factoring 21 is just too hard to expect for now. But that also pushes the date where pre-quantum cryptography is broken further into the future. If we still struggle to factor one of the smaller 5 bit numbers, factoring the 128 bit numbers necessary to break elliptic curve cryptography seems quite far away.