Comment by techdragon | Hacker News Reader

Comment by techdragon | Hacker News Reader

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While a room temperature superconductor would potentially have some uses in building a CPU… it’s not as relevant as you might think due to the semiconductor being the operating physics at play to make the transistors and perform the electrical switching and everything stemming from that underlying electrical unit.

You could absolutely use superconductors for all the connecting wires, and with a little engineering it might also be good for conducting heat away from the chip die as part of the larger CPU package… it wouldn’t be a good interface material (pins for connecting to the motherboard) as you want oxidisation resistance and a level of ductility and malleability to help with making a very good electrical connection between the surfaces when they are mechanically pressed together. But overall it will have some uses, it’s just not an immediately applicable technology for the silicon chips themselves… lots of potential in circuit designs and I’m sure if someone invented a way to lay this material onto a PCB as easily as we can print copper traces on them today that inventor would get pretty rich… it’s just not likely to make much of a change to the silicon chip die itself due to the need for semiconductors to do the transistor switching …

Of course someone might have invented a superconducting transistor that I haven’t heard of and if that’s the case disregard most of what I’ve just written haha.

I found a Wikipedia article about the topic: https://en.wikipedia.org/wiki/Superconducting_computing

Turns out that some research groups have already built superconducting CPU, albeit tiny ones.

I thought there was something out there like this but I wasn’t sure if it had actually built practical devices yet, cool to see where the state of the art has gone since I was last deeply involved in the ASIC & VLSI world. From what I read there I’d expect significant developments based on a number of the technologies outlined in that article if we do indeed have a room temperature superconductor we can build miniature circuits with…. But one issue I don’t think they mentioned will be grain sizes our transistors are getting very very small with current lithography technology. And it may be difficult to get equivalently small features (to use the industry term for the wires and bits we build silicon chip transistors out of) using superconducting materials where we have to control grain sizes and multi element mixtures, there will be lots of work on it so I’m sure it may change, but there will be a fundamental difference in how small we can make the conductor if it involves having multiple elements and crystal grains in specific structural arrangements, unlike a pure metallic wire which can be as thin as a few atoms (at this size your limits entirely depend on how tolerant you are of electrons accidentally tunnelling to other nearby conductors)

> but there will be a fundamental difference in how small we can make the conductor [...]

Considering how much faster super conductor logic circuits have been demonstrated to be driven [0] it might be worth the trade even with a higher fundamental limit on feature size.

A super conducting chip with far less logic could easily beat CMOS in: (1) Power performance (2) Single threaded performance (where CMOS has stalled) - but interestingly it could still compete in total throughput if the raw frequency is high enough. i.e even though there may be far less logic available compared to the latest and greatest CMOS lithography techniques - if it runs so much faster, less or simpler cores can potentially match or beat the throughput of the more parallel and specialised but slow logic available in CMOS dies.

In short, it could be like taking a step back in time to the simpler, smaller CPU days, but a huge step forward in fundamental frequency. That actually sounds like a nice trade regardless, CPUs are so insanely complex these days.

</armchair physics>

[0] https://spectrum.ieee.org/superconductor-logic-goes-lowpower

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