Quantum Wires

Silverlancer writes "Room temperature superconductors have often been a hallmark of far-future science fiction. But fortunately for us, they're here today, according to MIT's Technology Review. Richard Smalley, winner of the 1996 Nobel Prize for the discovery of the buckyball, is currently heading a project to produce a prototype carbon nanotube superconductor. They've already produced some wires up to 100 meters long--the only thing left to do is figure out how to produce only a certain type of nanotube, the "5,5 armchair nanotube," that conducts so well that it can be considered a superconductor."

Comments

Armchair...

[isny]

I'm sure that in the next 5 minutes, the "5,5 armchair nanotube" will be criticized by the armchair physicists, the Slashdot equivalent of the armchair quarterback.

Re:Armchair...

[mikael]

And just in case anyone wants to know what exactly, a 5,5 armchair nanotube looks like, there are some images of models here.

Re:Armchair...

[Anonymous Coward]

And just in case anyone wants to know what exactly, a 5,5 armchair nanotube looks like, there are some images of models here.

They appear somewhat larger than I expected. Are they being held by nanohands, or is there still a couple of years worth of work ahead trying to miniaturize them?

Dr. Smalley talks to the senate

[Flywheels of Fire]

Interestingly,Dr. Smalley talked about armchair nanotube technology at the senate Oversight hearing on sustainable, low emission, electricity generation Full Committee Hearing almost one year ago. The full text is here.

Re:wires...

[pla]

great! now i have something geekish to use for bondage with girls.

Sure... Now you just need the girls.

really a superconductor?

[Al Clocker]

The article says that there is "almost no loss of energy." But real superconductors truly have zero resistance. Once you start a current in a superconducting loop it runs for years without decreasing. AFAIK a decrease has never been observed. The article is unclear about whether this actually is a super-conductor or not. Does anyone know for a fact?

Re:really a superconductor?

[fearofcarpet]

No. Superconductors must be able to form so-called Cooper Pairs in order for electrons to move in the coherent manner in which no energy is lost. I gather the rules are a little different at really small scales where tunneling becomes a much bigger issue and some of the energy relationships are backwards, but the principle is still the same; if electrons bang into something they lose energy.

Metallic carbon nanotubes, to the best of my knowledge, cannot be made crystalline (perfectly regular) over large enough domains for this to happen thus there is "minimal energy loss" and they are really just very, very, very low resistance conductors (you can tell the difference by looking at the temperature dependance of the resistance).

The thing is, unless you want to build a mag-lev train, you don't really need a perfect super conductor. Right now the conductivities of the metals used in electronis are around 10^6 - 10^10 (inverse ohms per centimeter) and you can put your hand on your computer case to see just how much energy is dissipated as heat. If you increased those conductivities (with metallic carbon nanotubes for example) then your heat sink shrinks and your clock cycles come up... Assuming we can wire teeny tiny circuits with nanotubes. More importantly, you can drive portable electronics with less power, and thus smaller batteries.

BTW (regarding the very first post), some of the Slashdot Armchair Scientists (there are other sciences besides physics too you know) out here in computer land have Masters and PhDs and have published or worked in the field. Some of us have even met and/or worked with the people mentioned in the articles. I wouldn't be so quick to push aside honest criticism, afterall that is what scientists are trained to do - be skeptical :)

Re:really a superconductor?

[triplepoint217]

Carbon nanotubes are not superconductors. In an ideal (the kind they are trying to build), they have a resistance that is independent of length, however it is not zero like in actual superconductors. The resistance of an individual nanotube is about 20 kOhms, but because they are so small an array of a large number of them in parallel can have a small resistance, and still not be very large. Because the restance does not increase for longer tubes, they are similar to a superconductor, and would be useful for transmitting power over long distances. However, the physics behind the conduction is different.

Re:Optical Computing versus Quantum Wires

[Anonymous Coward]

I think it will be some supoerposition of both technologies, but once you open the datacenter door, it will be one or the other. Oh, and watch out for the dead cat.

superconductor != 0 resistance

[joostje]

conducts so well that it can be considered a superconductor

The most essential thing about a superconductor isn't the zero resistance, but the meissner effect. So if they manage to create wires with near-zero resistance, they will not have created `near-superconductors'.

For energy transportation and storage it doesn't matter all that much, cause zero resistance (even without superconductivity) would make energy transportation and storage better

LEDs

[Interrupt18]

There was a discussion yesterday about using LEDs to replace incandescent lights. One thing that came up was the power losses associated with stepping down the mains voltage to voltages required by LEDs.

Even if the carbon nanotubes are not technically superconductors, if their resistance is much lower than copper they might be ideal for low voltage home wiring. You could step the mains down to 5 or 12 volts in a central location in your house, and power the all your low voltage electronics without having to worry about I^2R losses.

Re:Dubious Logic

[nrlightfoot]

Actually, it's called a ballistic conductor. There is a small resistance when electrons pass through the ends of the nanotube, and while it is traveling along the rest of the tube there is no resistance.