4 ms·

By ohm's law, zero resistance means infinite current. I don't know anything about super conductors, but I thought that was the appeal? If not, what replaces ohm

By ohm's law, zero resistance means infinite current. I don't know anything about super conductors, but I thought that was the appeal? If not, what replaces ohms law in a superconductor? Or, put differently, how is the current limit defined?

XorNot 13y ago
The critical current does. Superconductivity is eventually destroyed by magnetic fields, so all superconductors can only carry so much current before they quench and become regular conductors. But this isn't a superconductor - it's a ballistic conductor. The idea is that it'll ballistically transport electrons with certain energy levels, which is functionally superconductivity (they don't lose energy to the conductor itself). But, since only electrons with a certain energy can enter in the first place, and since the energy levels are defined as a Boltzmann distribution, they still have a resistance which is proportional to the band of electron energies which cannot enter. So at RT it's great for a CPU, where the problem is you don't want heat being created on the die itself. But it doesn't allow you to do long-distance transmission like we'd like to with regular superconductors (since it would still have a resistance), and the mono-monolecular nature implies it wouldn't scale anyway.
- Florin_Andrei 13y ago
  Sounds like whatever "resistance" they may have, is all at the interface.
- hythloday 13y ago
  Thanks so much for this comment - when reading the article I noticed it carefully circumlocuted "superconductivity", and was curious what the difference was. This perfectly explains it (and goes into further interesting detail), which is exactly what I wanted.
powertower 13y ago
By the speed of light and the carrying capacity of the electron "channels".
colanderman 13y ago
Ohm's law only applies to linear components, of which exactly 0 exist in nature. Everything approximates linearity to varying degrees – resistors approximate it over a wide range of currents (up until they melt); MOSFETs approximate it until they reach saturation; diodes approximate it only infinitesmally.

XorNot 13y ago

The critical current does. Superconductivity is eventually destroyed by magnetic fields, so all superconductors can only carry so much current before they quench and become regular conductors. But this isn't a superconductor - it's a ballistic conductor. The idea is that it'll ballistically transport electrons with certain energy levels, which is functionally superconductivity (they don't lose energy to the conductor itself). But, since only electrons with a certain energy can enter in the first place, and since the energy levels are defined as a Boltzmann distribution, they still have a resistance which is proportional to the band of electron energies which cannot enter. So at RT it's great for a CPU, where the problem is you don't want heat being created on the die itself. But it doesn't allow you to do long-distance transmission like we'd like to with regular superconductors (since it would still have a resistance), and the mono-monolecular nature implies it wouldn't scale anyway.

Florin_Andrei 13y ago
Sounds like whatever "resistance" they may have, is all at the interface.
hythloday 13y ago
Thanks so much for this comment - when reading the article I noticed it carefully circumlocuted "superconductivity", and was curious what the difference was. This perfectly explains it (and goes into further interesting detail), which is exactly what I wanted.

powertower 13y ago

By the speed of light and the carrying capacity of the electron "channels".

colanderman 13y ago

Ohm's law only applies to linear components, of which exactly 0 exist in nature. Everything approximates linearity to varying degrees – resistors approximate it over a wide range of currents (up until they melt); MOSFETs approximate it until they reach saturation; diodes approximate it only infinitesmally.