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First Superconducting Transistor Created
holy_calamity writes "New Scientist reports that the first working superconducting transistor has been created, by researchers at the University of Geneva. Field effect transistors with zero electrical resistance would allow much faster operations. Only drawback is they need to be supercooled, something that may be addressed by improving the materials used."
Honestly, I do not think that room temperature superconductors should be necessary in order to give us incentive to utilize superconducting transistors in products of some sort. A superconducting transistor capable of functioning properly at temperatures that could be maintained by liquid nitrogen would be more than sufficient to give rise to viable commercial products, albeit only for a small niche within the greater computing market. Obviously LN2 just isn't going to work in a handheld or portable device; however, it should be simple enough to keep even a desktop processor chilled by LN2 without having to resort to frequent trips to a supplier to refill numerous dewars.
That all depends on what you consider 'room temperature'. To me, that doesn't mean actual room temperature, it means a temperature that can be achieved with small, economical cooling systems. I could see all the way down to -50 degrees C being practical for in home use. Considering the record for superconductivity is around -135 C, we're really not all that far away. In fact, seen as liquid nitrogen is relatively cheap to produce, if transistors existed above that temperature it would be possible to begin large scale experimentation now.
Also, it's important to keep in mind that we don't have a working theory for how the newer higher temperature superconductors work. It's within the realms of imagination that when we finally come up with an explaination, research will proceed much more rapidly. The highest temperature superconductors known today were found essentially by trial and error.
We have no idea how far away we are. We don't fully get it and are pretty much trying substances at random. We might figure out something that works next year or never. It's not something you can predict with any accuracy.
It is no longer uncommon to be uncommon.
I'd think that they would become useful first in places that are already using superconductor devices, like medical sensors and photo sensors.
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
We'd love to get our hands on some superconducting FETs. The ones I'm designing around right now have 5 milliohms Rds, and they're *still* getting so hot we have to solder big heat sinks onto the backsides of them.
But this just shifts the problem to the gate drive, because during any finite time period between 'off' and 'on' the FET acts like a big power resistor and heats up. Even if people ever make these so they're superconducting at room temp, they'll still heat up when in the active region. (Or we'd need to develop drivers that could produce instantaneous off/on transition times.) So we'd need ones that could remain superconductive in well over room-temp transients. If you have a superconducting FET that suddenly stops superconducting because of a temperature peak, it'll vaporize just about instantaneously. These would be an exciting gamble.
Nostalgia's not what it used to be.
Yes, you can insulate a device, so that in almost all cases (definitely in the case of a fast-switching transistor) the main heat source is the device itself.
Here's a commercial box that cools a 2-inch wafer of high-temperature superconductor to around 80K. This box uses 80 watts including whatever other signal processing stuff is in there.
Another source (Cryogenics 42 (2002) 705-718) says that 1W of cooling power at 4K will cost you 5kW of input power using a straightforward helium compressor. This scales as 1/temperature^2 for higher temperatures, but for lower temperatures you'd switch to a different type of refrigerator.
0.3K refrigerators using helium 3 would not use more than 10kW, but this is already too much for most applications.
So the practical significance of this research is that it may be reproduced with higher temperature materials, not that we will build THz DSPs at 0.3K.
what if the enclosure ruptures and explodes like a capacitor?
Why would it do such a thing? I don't see much resemblance between a computer case and a capacitor, and you can have liquid nitrogen in the open air without any sort of explosive effects. I mean, I'm no expert, so I could be totally wrong but...
What if it leaks nitrogen into the room and asphyxiates my cat sleeping on the floor?
I really can't see how this would happen either. About 80% of the air you breath is nitrogen. Nitrogen is lighter than oxygen, so it'll rise harmlessly to the ceiling once it warms up. And if it's still cold and dense enough to sink to the floor, I think your cat would wake up and run away from the cold air long before it was asphyxiated.
I'm not saying such a system would necessarily be feasible or practical, but calling it dangerous seems like a stretch.
Having LIQUID NITROGEN in my desktop PC would seem to present maintenance and disaster potential an order of magnitude greater than that: what if the enclosure ruptures and explodes like a capacitor? What if it leaks nitrogen into the room and asphyxiates my cat sleeping on the floor?
Years ago, I did Unix administration for the School of Science for a small university. The server room was behind the NMR lab (with its large superconducting magnets) and I had to go through the NMR lab to get to the sever room. In fact, the sever room was also used to store a 100 litre tank of LN and 100 litre tank of LH. The tanks will not explode. In fact, they leak a tiny amount of nitrogen and helium all the time. Even in the closed sever room (it had its own AC, seperate from the building AC), this was not a problem.
Also, a PC is not like a superconducting magnet: It will not 'quench' and cause the LN to rapidly evaporate. Even if it did, a PC is not going to contain much LN - less than 1 litre. A magnet (at least back then) would have 50 (or more) litres of LN (and LH). The affect on a the nitrogen level of the 20x20 room was negligible, even at floor lever. And, if your PC did quench, the noise of the escaping gas would almost certainly wake your cat or dog (with the likely size of the relief orifice in the PC would result in a piecing ultrasonic whistle, which cats and dogs cat hear).
(FWIW, the most, be far, dangerous aspect of a magnet quench is the helium. But that clings to the ceiling. Being cold, it also condenses water vapor, forming a cloud.)
Don't try to out wierd me, three-eyes. I get stranger things than you, free with my breakfast cereal. --Zaphod Beeblebr
Think of power converters. Think of a broadcast TV transmitter.