Fermionic condensate

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Deborah Jin

A fermionic condensate, or fermi condensate, is a state of matter (superfluid phase) which is very similar to the Bose–Einstein condensate, which are also superfluids.[1]

The only differences are that Bose-Einstein condensates are made up of bosons, and are social with each other (in groups, or clumps) and fermi condensates are anti-social (they don't attract each other at all. This has to be done artificially).

This state of matter was made in December 2003 by Deborah Jin and her group. Jin works for the National Institute of Standards and Technology at the University of Colorado.[2] Her team created this state of matter by cooling a cloud (this process is known as condensation) of potassium-40 atoms to less than a millionth°C over absolute zero (-273.15°C, this is the hypothetical lowest limit of physical temperatures). This is the same temperature required to cool matter to a Bose–Einstein condensate.

Albert Einstein, one of two men who hypothesised about Bose–Einstein condensates in the 1920s.
Satyendra Nath Bose, the man who worked with Einstein to come up with the idea of Bose–Einstein condensates. He is also famous for his Bose–Einstein statistics.

Difference between fermions and bosons[change | change source]

This is the standard model of elementary particles, usually referred to as just the Standard Model.

Bosons and fermions are subatomic particles (particles smaller than an atom). The difference between a boson and a fermion is the number of the atom's electrons, neutrons and/or protons. Any atom is composed of bosons if it has an even number of electrons, and any atom is composed of fermions if it has an odd number of electrons, neutrons and protons. An example of a boson would be a gluon. An example of a fermion would be potassium-40, which is what Deborah Jin used as the gas cloud. Bosons are social, so they are in clumps, and are attracted to each other, whereas fermions are anti-social. Fermions are usually found in straight strings of the particles, indicating that they repel each other. This is so, because fermions obey the Pauli exclusion principle, which states that they cannot gather together in the same quantum state.

Similarity to Bose–Einstein condensate[change | change source]

Like the Bose–Einstein condensates, fermi condensates will coalesce (grow together into one entity) with the particles that make them up. Bose–Einstein condensates and fermi condensates are also both man-made states of matter. The particles that make these states of matter have to be artificially super-cooled, to have the properties that they do. If they weren't artificially made, then scientists wouldn't have had to wait for almost a century to achieve temperatures near to absolute zero. Although, fermi condensates have reached temperatures lower than Bose–Einstein condensates. Also, both states of matter have no viscosity whatsoever, which means that they can flow without stopping, as they do not possess that property of normal fluids.

Helium-3 and fermions[change | change source]

To create a fermi condensate is very difficult. Fermions obey the exclusion principle, and they cannot be attracted to each other. They repel each other. Jin's research team and her found a way to merge them together. They adjusted and applied a magnetic field on the anti-social fermions, so they began losing their properties. The fermions still kept some of their character, but behaved a bit like bosons. Using this, they were able to make separate pairs of fermions merge with each other over and over again. Mrs. Jin suspects that this pairing process is the same in Helium-3, also a superfluid. Based on this information, they can hypothesize (make an educated guess) that fermionic condensates will flow without any viscosity as well.

Superconductivity and fermionic condensates[change | change source]

Another related phenomenon is superconductivity. In superconductivity, paired electrons can flow with 0 viscosity. There is quite some interest in superconductivity, as it may be a cheaper and cleaner source of electricity. These can also be used to power levitating trains, and hover-cars.

But, these dreams can only be fulfilled if superconductors can reach room temperature. In fact, a Nobel Prize will be awarded to one who succeeds in making a room temperature superconductor. Right now, the problem is that scientists have to work with superconductors at around -135°C. This involves the use of liquid nitrogen and other cryogenics (cryogenics is the study that deals with low temperatures). This is of course a tedious job, which is why scientists prefer to use superconductors at room temperature. Mrs. Jin's team thinks that replacing the paired electrons with the paired fermions would result in a room-temperature superconductor.

References[change | change source]

  1. Guenault, Tony 2003. Basic superfluids. Taylor & Francis. ISBN 0-7484-0892-4
  2. Rodgers, Peter & Dumé, Bell 2004. Fermionic condensate makes its debut. PhysicWeb. [1]

Other websites[change | change source]