6 ms·

Nanowire could provide a stable, easy-to-make superconducting transistor

41 points by el_duderino 6y ago

sradman 6y ago
> In 1956, MIT electrical engineer Dudley Buck published a description of a superconducting computer switch called the cryotron. The device was little more than two superconducting wires: One was straight, and the other was coiled around it. The cryotron acts as a switch, because when current flows through the coiled wire, its magnetic field reduces the current flowing through the straight wire. > [Karl Berggren] dubbed his superconducting nanowire device the nano-cryotron in tribute to Buck... The nano-cryotron uses heat to trigger a switch, rather than a magnetic field. Dudley Buck's cryotron: https://en.wikipedia.org/wiki/Cryotron https://en.wikipedia.org/wiki/Cryotron
nickthemagicman 6y ago
If laptops had superconductors would the battery life increase? Also am I thinking too small for the potential of superconductors?
- simiones 6y ago
  By my understanding, a superconducting computer does consume less power than a traditional computer, even taking into account the cooling systems. However, superconductivity requires either extremely low temperatures (a few kelvins at most) or even more extreme pressures (think many kilometers underground), so it is currently outside the realm of possibility for a mobile device.
  - nynx 6y ago
    actually, it's more like within a factor of two of the pressure at the center of the earth.
  - SiempreViernes 6y ago
    Well, some types of superconductors work fine at the simply low temperatures provided by liquid nitrogen (77 K). Though there are other factors like ability to be made into wires and how much current they can carry before switching out of superconductivity you might be having in mind with your single Kelvins number.
- ben_w 6y ago
  Yes to both, if you can do it at STP. Superconductors make practical many things which are otherwise extremely expensive or just plain impossible.
TobySKT 6y ago
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SiempreViernes 6y ago
Not really clear to me why the choke wire needs to be superconducting too, or indeed if it really is superconductive in any important sense of the word. The point seems to be that the choke wire quenches easily and provides heat from internal resistance. Also, this sounds like it is purely a switching transistor since superconductors aren't really grey-area type of things, you get them in the superconducting state or in the normal state and the transition is about as smooth as that from water to steam.
peter_d_sherman 6y ago
I like the idea a lot and am not criticizing this article, it's author, or the concept, but a few quick "minor corrections" if I might: >"Superconductors — materials that conduct electricity without resistance" "Superconductors — materials that conduct high amperages at low voltages without heat" >"Most metals lose resistance and become superconducting at extremely low temperatures, usually just a few degrees above absolute zero." Most metals, even small cross-sections -- can already conduct huge amounts of amperage -- but the electricity so passing must be conditioned so as to be at a high enough voltage -- to prevent heating effects. A good example of this would be a high-voltage transmission line; those tall steel towers carrying aluminum cables. The amount of electricity that they carry is enough to melt a small building -- but the cables themselves, despite being much smaller in diameter, never melt -- why is that? -- this is because the electricity is at high voltage... So is metal with electricity running through it at high voltage a superconductor? Technically not, because there are power losses over long enough distances. Also, it would not surprise me if everything (every metal that is, and possibly non-metals as well) -- becomes superconducting at a few degrees above zero... In other words, superconductivity -- might be more of a property of temperature -- than it is of the underlying material... Now, combine that idea with the idea that electricity can be conditioned in various ways to enable greater degrees of conductivity (voltage is one, frequency is another) -- without heat -- and then we might have a larger understanding of the underlying Physics... That being said (and I hope it was not taken as a criticism -- it was not intended to be!), I do like and appreciate very much the idea of superconducting nanowire!
- BenjiWiebe 6y ago
  Personally, I find the original more accurate and clear.
- peter_d_sherman 6y ago
  I'm even going to "double down" on my position on this, despite the downvote... My position, on this, is that Scientists, Physicists, in the future, should create tables, matrices, where they test every single element and compound, and they test conductivity at all temperatures -- but they also do this with A/C current at different frequencies and voltages. So we're looking at the combination of material, temperature, frequency, and voltage. Now that would be one hell of a research experiment, should it ever take place. But from the tables/matrices so generated -- now you could start to work on an equation or series of equations for those things, which should (hopefully) be simpler and more interrelated than the ones today, and could potentially give some insight into the atomic sub-structure of materials... Oh, and then there are the crystalline patterns of materials -- that should be included as a criteria too in these tables/matrices. Also -- if someone doing this in the future really wanted to "go for broke" -- they'd import the concept of electrical impedance, and the concept of circuit halving, too. Simple example, an LC coil (that is, a circuit which is broken into two halves, one half inductor/coil (L), and one half capacitor (C) -- is a circuit with two halves). Well, different circuits have different forms of impedance along these "lines of halving". The goal, if someone truly wanted to understand electricity -- would be to create as many different types of "circuit halves" within a whole circuit, then measure these with respect to material, temperature, frequency, etc., etc. -- as described above... A person so doing... would probably discover some interesting things... Or at least might be able to refine existing disparate formulas into something a bit simpler and more holistic... So, downvote if you will! Remember that in the history of scientists, yesterday's crackpots -- are tomorrow's genuises! <g>
_8091149529 6y ago
This is quite a convoluted way of making an electrical switch. In brief, the carriers of supercurrent (Cooper pairs) in the channel are "depleted" (actually: broken up) by a local heater that raises the channel temperature above the superconductor's critical temperature. The circuit topology, a heater coupled to a superconducting wire to sense the local tempreature, is the same as in a transition-edge sensor (TES), and functionally identical to a supercondicting nanowire single-photon detector (SNSPD). [SNSPD does not have a separate heater.] These cryogenic detectors are typically used when a good electrical amplifier does not exist for the input radiation. A textbook example would be optical or x-ray photons. I believe the device will be terribly inefficient as a transistor. The root cause is that the electrical signal gets converted into heat and back: Heater current -> Electron heating -> Phonon (lattice) heating -> Breaking of Cooper pairs in the channel -> Suppression of (super)current. Once the heat is in the phonons (lattice vibrations), it can propagate anywhere in the chip substrate. Also, the active area needs to be continuously heated to maintain the resistive ("off") state. Since HN is mostly a computing-oriented forum: This transistor will not be used for general-purpose logic cricuits.

41 points by el_duderino 6y ago

> In 1956, MIT electrical engineer Dudley Buck published a description of a superconducting computer switch called the cryotron. The device was little more than two superconducting wires: One was straight, and the other was coiled around it. The cryotron acts as a switch, because when current flows through the coiled wire, its magnetic field reduces the current flowing through the straight wire. > [Karl Berggren] dubbed his superconducting nanowire device the nano-cryotron in tribute to Buck... The nano-cryotron uses heat to trigger a switch, rather than a magnetic field. Dudley Buck's cryotron: https://en.wikipedia.org/wiki/Cryotron https://en.wikipedia.org/wiki/Cryotron

nickthemagicman 6y ago

If laptops had superconductors would the battery life increase? Also am I thinking too small for the potential of superconductors?

simiones 6y ago
By my understanding, a superconducting computer does consume less power than a traditional computer, even taking into account the cooling systems. However, superconductivity requires either extremely low temperatures (a few kelvins at most) or even more extreme pressures (think many kilometers underground), so it is currently outside the realm of possibility for a mobile device.
- nynx 6y ago
  actually, it's more like within a factor of two of the pressure at the center of the earth.
- SiempreViernes 6y ago
  Well, some types of superconductors work fine at the simply low temperatures provided by liquid nitrogen (77 K). Though there are other factors like ability to be made into wires and how much current they can carry before switching out of superconductivity you might be having in mind with your single Kelvins number.
ben_w 6y ago
Yes to both, if you can do it at STP. Superconductors make practical many things which are otherwise extremely expensive or just plain impossible.

TobySKT 6y ago

By providing custom telemedicine software development services, our aim is to transform the way patients and healthcare providers communicate by using emerging technologies. Our developers ensure your telemedicine solution complies with regulatory standards such as HIPAA and HL7 and all telemedicine software development standards. https://steelkiwi.com/expertise/telemedicine-software-development/ https://steelkiwi.com/expertise/telemedicine-software-develo...

SiempreViernes 6y ago

Not really clear to me why the choke wire needs to be superconducting too, or indeed if it really is superconductive in any important sense of the word. The point seems to be that the choke wire quenches easily and provides heat from internal resistance. Also, this sounds like it is purely a switching transistor since superconductors aren't really grey-area type of things, you get them in the superconducting state or in the normal state and the transition is about as smooth as that from water to steam.

peter_d_sherman 6y ago

I like the idea a lot and am not criticizing this article, it's author, or the concept, but a few quick "minor corrections" if I might: >"Superconductors — materials that conduct electricity without resistance" "Superconductors — materials that conduct high amperages at low voltages without heat" >"Most metals lose resistance and become superconducting at extremely low temperatures, usually just a few degrees above absolute zero." Most metals, even small cross-sections -- can already conduct huge amounts of amperage -- but the electricity so passing must be conditioned so as to be at a high enough voltage -- to prevent heating effects. A good example of this would be a high-voltage transmission line; those tall steel towers carrying aluminum cables. The amount of electricity that they carry is enough to melt a small building -- but the cables themselves, despite being much smaller in diameter, never melt -- why is that? -- this is because the electricity is at high voltage... So is metal with electricity running through it at high voltage a superconductor? Technically not, because there are power losses over long enough distances. Also, it would not surprise me if everything (every metal that is, and possibly non-metals as well) -- becomes superconducting at a few degrees above zero... In other words, superconductivity -- might be more of a property of temperature -- than it is of the underlying material... Now, combine that idea with the idea that electricity can be conditioned in various ways to enable greater degrees of conductivity (voltage is one, frequency is another) -- without heat -- and then we might have a larger understanding of the underlying Physics... That being said (and I hope it was not taken as a criticism -- it was not intended to be!), I do like and appreciate very much the idea of superconducting nanowire!

BenjiWiebe 6y ago
Personally, I find the original more accurate and clear.
peter_d_sherman 6y ago
I'm even going to "double down" on my position on this, despite the downvote... My position, on this, is that Scientists, Physicists, in the future, should create tables, matrices, where they test every single element and compound, and they test conductivity at all temperatures -- but they also do this with A/C current at different frequencies and voltages. So we're looking at the combination of material, temperature, frequency, and voltage. Now that would be one hell of a research experiment, should it ever take place. But from the tables/matrices so generated -- now you could start to work on an equation or series of equations for those things, which should (hopefully) be simpler and more interrelated than the ones today, and could potentially give some insight into the atomic sub-structure of materials... Oh, and then there are the crystalline patterns of materials -- that should be included as a criteria too in these tables/matrices. Also -- if someone doing this in the future really wanted to "go for broke" -- they'd import the concept of electrical impedance, and the concept of circuit halving, too. Simple example, an LC coil (that is, a circuit which is broken into two halves, one half inductor/coil (L), and one half capacitor (C) -- is a circuit with two halves). Well, different circuits have different forms of impedance along these "lines of halving". The goal, if someone truly wanted to understand electricity -- would be to create as many different types of "circuit halves" within a whole circuit, then measure these with respect to material, temperature, frequency, etc., etc. -- as described above... A person so doing... would probably discover some interesting things... Or at least might be able to refine existing disparate formulas into something a bit simpler and more holistic... So, downvote if you will! Remember that in the history of scientists, yesterday's crackpots -- are tomorrow's genuises! <g>

_8091149529 6y ago

This is quite a convoluted way of making an electrical switch. In brief, the carriers of supercurrent (Cooper pairs) in the channel are "depleted" (actually: broken up) by a local heater that raises the channel temperature above the superconductor's critical temperature. The circuit topology, a heater coupled to a superconducting wire to sense the local tempreature, is the same as in a transition-edge sensor (TES), and functionally identical to a supercondicting nanowire single-photon detector (SNSPD). [SNSPD does not have a separate heater.] These cryogenic detectors are typically used when a good electrical amplifier does not exist for the input radiation. A textbook example would be optical or x-ray photons. I believe the device will be terribly inefficient as a transistor. The root cause is that the electrical signal gets converted into heat and back: Heater current -> Electron heating -> Phonon (lattice) heating -> Breaking of Cooper pairs in the channel -> Suppression of (super)current. Once the heat is in the phonons (lattice vibrations), it can propagate anywhere in the chip substrate. Also, the active area needs to be continuously heated to maintain the resistive ("off") state. Since HN is mostly a computing-oriented forum: This transistor will not be used for general-purpose logic cricuits.