Ballistic Quantum Wires Conduct Superbly 9
haleos writes: "Physics Web ran an article on Ballistic Quantum Wires which allow resistance free current flow without the super-low temperatures of present-day superconductors. Just think of what a superconducting quantum wire could do for the speed of your future pocket computer!" Rather than low temperatures keeping atoms in line, these wires gain their properties from ultra-precise manufacturing techniques.
This is not superconductivity (Score:1)
Re:Still needs cooling. (Score:1)
Will this help in controlled Fusion? (Score:2)
Re:Still needs cooling. (Score:4)
Did you even read the article? You don't need to keep quantum wires cold at all, just so long as the structure isn't damaged. Any old piece of wire will superconduct at low enough temperatures, that's no big deal... quantum wires here superconduct because there's no defects that lead to resistance. Nothing in the article suggests low temperatures, or mentions Cooper pairs, which are typically found in a superconductor.
For those of you who do not know, a Cooper pair is a pair of electrons whose close proximity allows their spins to cancel out, and acts as a "Boson" rather than a "Fermion." Bosons obey one sort of statistical laws, whereas Fermions obey another. Fermions have half-integer multiple spins, and bosons have whole-integer multiple spins, so combining two fermions together creates the effect of a boson. Because bosons do not follow the Pauli exclusion rule, they can all be in the same energy state, and flow through a superconductor unimpeded. The article does not mention this.
Once again, if they discovered that a tiny wire conducted electricity perfectly when very cold, that would not be news, that would be 100 year old history. It's a sorta moot point anyways, you won't be seeing this in your portable computer for a long time.
More on superconductors here. [inter.net]
Just my $.02
Re:Will this help in controlled Fusion? (Score:4)
First of all, the type of fusion you mentioned is called magnetic confinement fusion. It is as you said, where magnetic fields trap a plasma which is at a temperature high enough to fuse. While it is true that many problems with this stem from the fact that the field strength is limited, room-temperature superconductors would by no means magically fix this problem. If this was the only problem, we'd simply use normal superconductors. This, however, is only one type of fusion.
There are several other types of fusion, the most easily understood being inertial confinement fusion. Instead of using ultra-strong magnetic fields to contain the plasma, it attempts to use the inertia of the reacting particles to keep the material contained. Lasers hit by extreme bursts of laser energy accomplish this as they rapidly implode. Ion beams directed at each other at relativistic velocities are also another way of accomplishing this same effect.
A few more interesting types are muon catalysed fusion, and antiproton catalysed fusion. The latter is being investigated for its uses in propulsion (Here is an excellent link on NASA's page [nasa.gov] about it, my younger brother researched this as a school project and won first place.). Muon-catalysed fusion is a pretty wacky idea, shooting negatively charged muons (like electrons, only heavier) into a bunch of hydrogen, which causes sponaneous fusion to occur. A muon is a particle like an electron, but much heavier, produced easily by many particle accellerators. The problem with this sort of fusion is that producing muons takes a lot of energy, and you need a lot of muons.
There was a slashdot article [slashdot.org] earlier on the different types of fusion, which points to an excellent article.
To reiterate my point, these quantum wires are very small, and would not carry much current. This may be extremely useful for semiconductor chips (if you read they are already interfaced through semiconductors) and could allow very small chips that consume such small amount of power that they could be easily powered by the ambient RF radiation (Just think, talk radio would actually be good for something, he he he). There's a lot of uses, but sadly I don't think that small defect free wires will play much of a role in bringing about fusion.
Maybe someday...
Justin
Still needs cooling. (Score:1)
Not much, since you would still need a refridgeration unit to keep the 'wire' cold. Super low means on the order of a few Kelvin. High-temp superconductors means about the same temperature of Liquid Nitrogen or better.
A refridgeration unit in your pocket would be heavy, probably involve condensation (i.e. wet pocket), and it would emit heat.
Just think of... (Score:2)
In my opinion, not much. The largest obstacle in the way of infinitely fast computers is the switching time of the FETs and BJTs used to make up the logic gates etc. These largely arise from the resistance, capacitance and inductance of the material in the transistors themselves, which must be made with semiconductors.
These wires are conductors (sorry for stating the obvious) and thus could not be used to fabricate a transistor using any conventional (or even known) methods. So, I'm sorry folks, but the best way to faster computers is still probably decreasing the size of the gates on the transistors.
Re:Still needs cooling. (Score:1)
Re:Just think of... (Score:1)
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