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Comment by ajb117 | Hacker News Reader

I don't know much physics, but is there a reason we should be hoping for superconductivity specifically rather than a cheap material that's just a very very good conductor? Also, even if LK-99 were superconductive, that wouldn't imply it would be useful for computing, right? Surely there are materials that are better conductors than silicon but have mechanical and other physical quirks preventing us from using then for chips.

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Silicon is not valuable because it is a good conductor, in fact it is actually more like an insulator in its natural state. However, mixing the right materials into it, it becomes a very good semiconductor. So it can let current flow easily or block it effectively, making it a good basis for transistors. The problem here are the normal (usually copper) wires between transistors that cause heat to build up whenever current flows through them. That limits how densely you can pack wires in a chip. With a superconductor, we could not just have much smaller and much faster processors, we could also have many designs that don't require cooling anymore. Imagine a power monster chip like the RTX 4090 running state of the art LLMs locally on your phone. That's the kind of stuff that's at stake here and that's also why everyone and their uncle wants to be author on the original paper.

How much of the cooling cost of current chips is due to wires, vs. the transistors themselves?

Superconductors will not help with the latter.

> The problem here are the normal (usually copper) wires between transistors that cause heat to build up whenever current flows through them.

IIRC with the high frequencies of modern processors switching losses tend to be a larger factor than resistive losses. If you can remove the resistive losses that leaves you with a greater heat budget from switching losses which might help drive up frequency even more.

Switch losses are also resistance losses, they just get amplified by things like the skin effect.

If you have a room temperature superconductor, does that mean you can make a superconducting transistor from it?

Dynamic current does not flow freely in superconductors, only direct current. So it would help for power circuits, not for data lanes.

A few practical things that we need superconductors for which currently require very expensive cooling:

1) MRIs — could be way cheaper, smaller and more ubiquitous with room temperature superconductors 2) Maglev trains — superconducters expel a magnetic fields that can make things "levitate" (called the Meissner effect). Maglev trains have minimal friction and are incredibly energy-efficient. 3) Quantum computing — most designs require cooled superconductors. Room-temperature superconductors are a requirement for future portable quantum computers, or quantum chips that sit side-by-side in conventional computers

There's a ton more implications, just think about how everything from electric cars to smartphones was only possible due to modern batteries — that's the scale of technical innovations that could be built on this.

MRI is a potential application of room temperature superconductor in general, but not specifically for LK-99. One disadvantage of LK-99 is that it has very low critical current, see patent figure 10.

On the other hand, 300 mA is more than enough for computing applications.

We are still at the if-it-is-real stage. I would not take any wagers that the generation one release is indicative of an industrialized product performance.

It would be unlikely for the first observed room temperature superconductor to also be practical. LK99 contains lead which is something we are trying remove from consumer electronics.

What matters is all the investment and attention that would follow the verified discovery of such a material, the huge glut of research would surely yield even better candidates.

The ideal end goal is something like the superconducting tape that we already have, but that works without cooling and is preferably non-toxic.

Since there will be impurity anyway, there is no difference whatsoever in practice between zero and very very low resistance. Quantum Energy Research Centre in fact describes its resistance to be "lower than 1/10^4 of copper", not zero, which is very practical minded.

Since the company specifically developed thin film by vapor deposition method, I think we can be sure that computing is the intended application. Search for my other comments for details.

There is a lot more than just silicon wafers in our computers. Let's start with all those traces on board. Right now they are made of copper. But what if they could conduct with 0 resistance?

Sure, replacing copper wires help too, but the real deal is to replace copper interconnects inside the chips. It looks like the company is going for replacing copper interconnects in chips.

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