What are the properties and potential uses of Bose-Einstein Condensate?

[Denver Dang]

A quick question.
I just heard very little about this in a lecture today, so I have a few questions.

If I remember correctly my teacher said that when you hit a specific temperature, very low, the atoms in the gascloud, you are trying to cool, will be in the exact same quantum state. So does this mean, that the Pauli Principle doesn't "work" at these low temperatures, and does it mean that the spin, and any other quantum number, is the same for all atoms in this cooled cloud ?

And the last question, what can you use this for ? :)


Regards

 

[Sakha]

And the last question, what can you use this for ? :)

I've read that they use these condensates to slow down light to amazing low speeds. Quantum computing usually is done at really low temperatures, possibly at the state of a Bose-Einstein condensate.

As for the violation of the Pauli Exclusion Principle. I think the exclusion principle applies only to fermions that have half-integer spins, but Bose-Einstein condensates behave as Bosons (integer spins).

Anyways, let's wait for the pros to answer.

 

[zhermes]

If I remember correctly my teacher said that when you hit a specific temperature, very low, the atoms in the gascloud, you are trying to cool, will be in the exact same quantum state. So does this mean, that the Pauli Principle doesn't "work" at these low temperatures, and does it mean that the spin, and any other quantum number, is the same for all atoms in this cooled cloud ?

It depends on what you're trying to cool. Particles with half-integer spins ("fermions") obey "fermi-dirac" statistics; and particles with whole integer spin ("Bosons") obey "bose-einstein" statistics. In the former case, the exclusion principle always holds--and they are never able to have identical quantum states. In the latter case, the exclusion principle never applies, and they do tend towards the exact same quantum state.

Fermions in the extremely low temperature regime turn into a 'degenerate' state, while bosons turn into a 'condensate.' Both have extremely strange and interesting properties that I'm sure people are trying to do cool stuff with. The problem is, the temperatures are generally outrageously low to get these states.