IBM quantum computer solves classically intractable problem in 15 minutes

[u/National-Dragonfly35]

https://www.sciencedaily.com/releases/2026/08/260829035219.htm

"The researchers showed that their method preserves the same computational hardness criteria associated with RCS, meaning the problem remains extremely difficult for classical computers. At the same time, the added structure allows errors to be detected during the quantum computation."

[u/cookie_tech]

I'd argue that PQC (post-quantum cryptography) is slightly over-hyped.

I'm in the cybersecurity world and many well-respected cybersecurity experts believe that we may have a quantum computer that is powerful enough to break quantum computing by 2030.

Meanwhile, I have several colleagues who specialize in the physics side of quantum computing, and (according to them), even with recent breakthroughs, we are still optimistically decades away from a quantum computer that's powerful enough to break RSA.

Do I think it's important to prepare for worst-case scenarios? Sure. But, realistically anything encrypted now that is important enough to be relevant in 30+ years when RSA is finally broken has already been encrypted with PQC.

[u/Cryptizard → u/cookie_tech]

30 years is waaaay too optimistic. You can plot the growth in physical qubits and it is a very steady trend over the past 10 years, with no sign of stopping. That has us reaching Q-day in around 10-15 years.

BUT, most people ignore the fact that we are simultaneously finding more efficient circuits to implement Shor's algorithm. It has gone from 1 billion qubits, to 50 million qubits, to now under one million qubits to run Shor's algorithm on cryptographically relevant inputs.

And that also depends on how efficient error correction is. Right now we are assuming 1000 physical qubits per logical qubit, but since gate fidelities are also increasing steadily, that number could be much lower.

The best circuits we have take only ~800 logical qubits.

https://ecdsa.fail/

So the scaling here is going steadily in three separate axes at once, which all compound, with no signs of stopping in any of them. To take 30 years there would have to be some major unexpected roadblock that nobody is aware of. I wouldn't risk anything important on that bet.

A physicist is not going to know about algorithmic improvements or error correction improvements. They are only looking at one part of the picture.

[u/cookie_tech → u/Cryptizard]

I'm mostly just parroting what I've heard from people who know a lot more than me. Doing a little more research it does seem that projections seem to predict we'll have practical quantum computers ~15 years from now, and many experts agree that this is feasible.

I want to add two things. First is that companies always give overly optimistic projections. That's how they get venture capital or make shareholders happy.

Second, there are often physical barriers that we don't know about until we reach them. Take Moore's Law. Among a few other things, Moore's law used to state that clock frequencies would double every year. In 2003 Intel released a 3.2 GHz Pentium 4, and announced that they would have a 10 GHz CPU out by the end of the decade. However, when they attempted to create a 7 GHz Pentium 5, they realized the ran into a insurmountable power wall that seemingly came out of nowhere. By 2010 they hadn't even gotten to 4 GHz (partially because they shifted focus to thread count, but still).

As quantum computers get larger, I've been told that there are a lot of scaling challenges we have yet to overcome (mostly involving keeping large systems at absolute 0). Maybe we'll figure out a way past these problems and continue with current growth. Maybe we'll bottom out in the next few years and practical quantum computers will once again become a distant dream. At this point it's a guessing game for even the most expert quantum scientists.

edit: the doubling of clock frequencies was technically never apart of Moore's law. However, from 1975 until the we hit the power wall in 2005, clock speeds would double about every 2-3 years.

[u/Cryptizard → u/cookie_tech]

That example doesn't really work in your favor. It doesn't matter that chips didn't scale to higher GHz, that's actually not what Moore's law says. It says that the number of transistors in a chip doubles roughly every two years, and that trend has continued through to today.

As quantum computers get larger, I've been told that there are a lot of scaling challenges we have yet to overcome (mostly involving keeping large systems at absolute 0).

That's why we are moving to other qubit technologies like trapped ions that don't require extreme cooling.

Maybe we'll figure out a way past these problems and continue with current growth.

We already have. Also, the people who want to still work on superconducting qubits (the ones that have to be really cold) just keep building better refrigerators.

https://www.ibm.com/quantum/blog/modular-cryogenics

[u/cookie_tech → u/Cryptizard]

It doesn't matter that chips didn't scale to higher GHz, that's actually not what Moore's law says.

You've taken the wrong lesson out the story. While not technically part of Moore's law, the sudden stop of clock scaling was very disruptive for CPU performance. Single core performance dropped from a 51% yearly increase to a 21% yearly increase after the 2005 power wall was hit.

That's why we are moving to other qubit technologies like trapped ions that don't require extreme cooling.

My (limited) understanding is that the ions themselves still have to be cooled to microKelvin via lasers, which is a whole other scaling problem. There's a reason that these types of quantum computers are pretty far behind in terms of physical qubits.

I'm not saying we aren't making impressive progress. I'm saying I work alongside several quantum computing experts that have experience with both academic and commercial systems who, despite the impressive progress, cast doubt on current projections of achieving practical quantum computing in the next couple of decades.

[u/Foreign_Implement897 → u/Cryptizard]

Describe how trapped qbuts solve travelling salesman, man! You can do it man! You the best!

[u/Foreign_Implement897 → u/Cryptizard]

Intriqued, have you consideres ehat Gödel said? I think it is super relevant here. Also combine that with recent insights from SpaceX and Whitehouse.