Contents
Frequently
Asked Questions
- What does CryoComputing mean?
- What is a conductor?
- What factors effect how well conductors conducts electricity?
- What is a superconductor?
- What is resistance and where does it come from in conductors?
- How does lowering the temperature of a conductor lower the resistance of the conductor?
- How does lowering the resistance of a conductor effect computer speeds?
- What companies are working on CryoComputers and what have been their results?
CryoComputing can be broken into two parts, Cryo and Computing. Cryo means cold, and computing refers to the use of electronic devices. In general, CryoComputing refers to the use of cold in computers.
A conductor is any substance that allows the flow of electrons, that is, allows an electrical current to flow through it.
What
factors effect how well conductors conducts electricity?
There are three major factors that effect how well a conductor allows the flow of electricity:
- size
- purity
- temperature
This report generally discusses the last factor, temperature.
A superconductor is a conductor that allows electricity to flow extremely well. There is very little resisting the flow of electricity in a superconductor. In superconductors, the resistivity approaches zero.
Resistance is the force opposing the flow of current.
In technical terms, where does resistance come from in conductors?
Resistance in conductors is caused by collisions of the electrons with atoms in the crystal lattice of the material, and with phonons, which are quantums of lattice energy. As an electron is pulled through free space by an electric field, the constant force of the field is applied, causing the particle to undergo constant acceleration. Electric current, however, is known to be constant throughout the circuit. The apparent constant velocity is actually the result of repeated acceleration, followed by collisions in which the electron looses nearly all its energy, and must begin to accelerate from zero. The number of collisions an electron encounters as if flows through the conductor has a major effect on the materials conductivity.
How does lowering the temperature of a conductor lower the resistance of the conductor?
When the temperature of a conductor is lowered, the molecules of the conductor gather together. The denser material is easier for flowing electrons to move through.
That isn't technical enough. Can I know more?
Sure. Lowering the temperature of a conductor reduces the energy of the conductor, and therefore reduces the number of phonons, This decreased concentration of phonons reduces the electron scattering, increasing conductivity. Because of reduced phonon collisions, electrical resistance is proportional to temperature T at lower temperatures, while at higher temperatures, the resistance is proportional to temperature T. A classical physical explanation of the relationship between temperature and resistance also exists. In a metal the atoms are arranged in a crystal lattice. As temperature increases, the atoms vibrate more rapidly and more randomly about their given positions in the lattice. The opposite is true at lower temperatures. The atoms vibrate less, and are more closely confined to their positions. The apparent random motion of particles at high temperatures causes more collisions to occur, slowing the electrons further.
How does lowering the resistance of a conductor effect computer speeds?
When the resistance in microchips is reduced, electrons are allowed to move faster and without loss through materials. The computer on-off (high-low) signals it sends from one part of the computer to another are expedited when the conductors are cooled. Cooling the CPU is one of the most efficient ways to increase computer speed as CPU speeds are a bottleneck in the computer environment.
What companies are working on CryoComputers and what have been their results?
Both Intel and DEC are working on CryoComputing technologies. This is exciting new technology, so neither company is saying a lot about what they are doing to protect their secrets while they develop this technology. However, Intel recently announced breaking the one GHz CPU speed barrier -- through the use of CryoComputing. You may read about in at the Intel newsroom. (Intel and DEC are trademarks of their respective companies)
