They seem to have pretty similar characteristics, I am asking what makes them different from each other besides the fact that superfluid is seen in helium isotopes while BEC is gotten from rubidium.
Thanks for any answers in advance.
2006-09-06 12:34:20 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
BEC (Bose-einstein condensate) is what happens when a substance is cooled down so far that the atoms (it only happens with some atomes) pair up and act like bosons rather than fermions (you have to look that up, i am to lazy to explain the differance right now)
a substance that is a super fluid (or rather has the properties of superfluidity) is simply a liquid that is in a BEC state. As far as I know this behavior is unique to Heleium, but i could be wrong about that. Because helium is the only substance that will remain a liquid at temperatures that are required for a substance to be a BEC
2006-09-08 03:23:50 · answer #1 · answered by farrell_stu 4 · 0⤊ 1⤋
The thermodynamics of the superfluid transition are similar to, but not exactly the same as, those of the BEC. The superfluid is a collective state stabilized by interactions--the BEC is a highly "compressed" state of a gas. Because of the interactions, there is an excitation gap in the superfluid--this is what gives rise to its "superfluidity". The excitation spectra are different--SF helium 4 has a roton spectrum, which is linear for low momenta. This reduces the density of states for low-energy/finite momentum excitations. At higher momenta the roton spectrum looks kind of like a phonon spectrum in that it has a peak--more evidence of collectivity.
2006-09-06 12:58:59 · answer #2 · answered by Benjamin N 4 · 0⤊ 0⤋