Researchers identify new type of superconductor | Hacker News Reader

Researchers identify new type of superconductor

news.cornell.edu

104 pointsckastner21 comments

Okay, that you could use ultrasound spectroscopy to work on this problem was not something I've read before. So very cool that.

But what is more interesting to me is the last bit where they posit that they now know so much about the physics of Sr2UO4 that they may be able work backwards into a more general understanding of super-conductivity, that I find really intriguing.

Like many people I bought a sample of YBCO and floated magnets over it when cooled with LN2. And I kept hoping we'd get a reasonable theory that would let us engineer a material that was superconductive at a temperature we could chill without LN2. But years later, here we are.

So I'm really hoping this moves us closer to a more complete understanding of the atomic structures that enable superconductivity and how to build them.

Beyond high temperature superconductors, p-wave superconductors would be a big deal. The article mentions that one could use them to build Majorana qubits (Microsoft has a significant effort in this direction). The cool thing about Majorana qubits is that they are hypothesized to be orders of magnitude less noisy than the current types of qubits (the quantum state there is a topological property).

Is this the anyonic computing I heard about several years ago or is it another line of quantum computing research also funded by Microsoft?

Would mass production of room temperature superconductors (effectively science fiction right now I believe) be as game changing for processing power as it seems by eliminating heat issues?

https://en.wikipedia.org/wiki/Superconducting_computing

Apparently. Whole article sounds like science-fiction. 500x efficiency increase while scaling operating frequencies 250x.

Drilling down into the sources suggests that the top-level claims are a bit of a reach:

> Specifically, while superconducting technology eliminates the cost of moving bits within the superconducting domain, the cost of transferring data from the outside into the superconducting domain does dissipate energy at 4 K. Consequently, superconducting is expected to perform poorly on, for example, big data applications where the bulk of data is streamed from the outside into the processor. What is more, the energy cost of logic in superconducting circuits is expected to be similar to that of CMOS.

This is true for now. The IARPA SuperCables program exists to tackle this specific problem. Probably the solution will require converting microwave pulses into optical frequencies to get the signals out of the cold spaces with fiber-optic infrastructure.

If you read the broad agency announcement, they even have explicit energy dissipation targets (per bit). I think it’s something like attoJoules or femtoJoules?

https://www.iarpa.gov/index.php/research-programs/supercable...

You seem to be quoting [0].

This isn't really my area of expertise, but the 4K referenced here seems to be the operating temperature.

I imagine the thermodynamics of moving data around changes if you have room-temperature superconducting materials and aren't constrained to cryogenic computing, but I am not really sure what the impact would be on mitigating (or exacerbating) this kind of data transfer cost.

[0]: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.10...

Yes. It would be transformative in ways both readily imagined and yet to be imagined.

It isn't entirely sunshine and rainbows, as one must take care to remain below the material's critical field for it to remain superconducting, but beyond that, much of what a thoughtful freshman-physics student might dream up is likely to be possible.

Such a discovery would revolutionize a lot more than power-transmission. One of the first places it would have impact is in MRI, where magnet-cooling is a major expense. The ripple effects of such a discovery would be very fast, just as high-Tc was in 1986/1987. Even if the material is a strange one, everyone would race to find a way to use it.

Edit: First applications might probably appear in situations that can use small quantities of the material -- building great filters in circuits/ICs would require minimal material-handling R&D.

Depends on quite a bit more than the temperature. What about the cost? Max power handling? Maximum magnetic flux?

Sure if it's cheap you could do fun things like have a solar powered grid so what any sunny place on earth could provide power planet wide. Thus any natural peaks and valleys world wide would mostly average out. That way instead of designing your power grid for the worst case (something like sunset of the hottest day of the year) you can balance the northern hemisphere with the southern (with generally opposite weather).

It also could potentially make for "perfect" batteries, which could revolutionize various industries. Unfortunately zero resistance does not imply infinite power density.

I’ve never been able to find what the power density would be on a superconducting coil battery.

For YBCO SMES, it is quite high on par with ultra-capacitors.

I wonder what energy density would look like for a room temperature sc if you didn’t need all the cooling equipment?

Or do they disregard that in your figure?

Amusing historical note: D-Wave is so named because early in the company's history, we* wanted to do high-temperature, or even "desktop" quantum computing. In the process of hashing out implementation details, it became clear that the problem with operating at room temperature is thermal noise: the colder you go, the better your results.

Turns out those d-wave superconductors wouldn't bring anything to the table, but many of them require tricky chemistry that would be much more complicated to fab than the metals we use.

* "we" the organization, I wouldn't join in for years yet

How big a deal is this? It sounds like it might not be g-wave but it could be

> "So then the only things that the experiments are consistent with are these very, very weird things that nobody has ever seen before. One of which is g-wave, which means angular momentum 4"

They say the transition temperature is 1.4 Kelvin, so I would guess that a new type of superconducting material is exciting, but this particular material does not hold much promise as a high-temperature superconductor.

It's a big deal for material scientists studying superconductivity but irrelevant otherwise, at least for now. Theoretical research on superconductivity practically hit a wall decades ago and there's been little to no progress despite significant amounts of effort and countless world changing applications like MRIs, NMRs, particle colliders, etc. A third type of superconductor might provide the missing data we needed to make real progress and unify the different types of superconductors under one theory.

This discovery is definitively cool, but not close to the phosphine-on-Venus cool. The present paper is similar to the former finding in the sense that what looked like a natural explanation (a p-wave order parameter) seems to have been ruled out (just like chemical origin of phosphine seems to have been ruled out). Hence, more exotic findings might lurk in this material.

I think this is mostly a propaganda piece from Cornell's PR. The land of superconductivity is full of over-promising and under-delivering, but truthfully you could say that about most research papers nowadays. The bottom line is that we've seen all these great promises that "X material will help us understand superconductivity better" but we're still pretty much holding the same level of understanding since BCS theory plus or minus some theoretical framework for type 2 superconductors. We have increased the library of materials that are superconducting though.

So the reality is that we haven't really found a new technology with our current library of superconductors, and I think that's the proof in the pudding, we're not there yet but boy is the field set for disruption. The hot application that pretty much every new paper on superconductivity will mention is superconducting qubits, and the search is for one that doesn't suffer much from decoherence, which is where spin-triplet superconductors appear to be candidates for.

I haven't kept up much with the quantum computer world this year due to covid, but at least as of last year everyone seemed to still be using Al as the superconductor instead of one of these more exotic alloys and compounds. That is what I mean by proof in the pudding, if someone can make a technology out of the material, then that's real, that's progress. Until then, most of these pieces released by university PR departments are just hype.

This is of course merely the opinion of an empiricist skeptic who finds peer review to be flawed, and that believes that the filter of time is best for determining what's real progress. Sometimes it can take us 50 years to go from discovery to application.

Ok, I guess I'm not surprised. I'm usually suspicious when the story is published on a .edu because it seems like it's often just marketing.

Pretty interesting stuff. Read the unpublished paper earlier this week potentially pretty ground-breaking

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