High Temperature Bose-Einstein Condensation Observed

ultracool writes "Two separate research groups claim to have observed Bose-Einstein condensation (BEC) in quasiparticles at much higher temperatures than atomic BEC — one at 19 Kelvin and the other at room temperature. The 19 K BEC was composed of half-matter, half-light quasi-particles called polaritons, and the room temperature condensate was composed of 'magnons' (packets of magnetic energy). There is some skepticism among physicists as to whether these really are BECs. If they are true BECs, these experiments are the first evidence of them in the solid state." Just in case you need a brush up on BEC, like I did, check out the Wikipedia article on Bose-Einstein condensation.

Comments

Solid State?

[FlavorText]

I thought Bose-Einstein condensate was a completely different state of matter. How then, could it appear in a "solid state"?

Re:Solid State?

[Engine]

Being in a BEC does not halt radioactive decay. I don't see why it should.

Radioactive decay does affect a BEC. Firstly, it frees energy that will heat the BEC. A BEC of atoms is so cold that even recoils from (ordinary light) photons destroys it, then imaging what the recoils from the decay would do. Secondly, a BEC can only consist of identical particles. Emitting a alpha or beta particle leaves you with an other species and this can no longer be part of the BEC.

I am a Ph.D. student actually working with BECs so I should know what I am talking about. I am not as confident expressing my thoughts in english, so sorry for any confusion I might cause.

A *live* Wikipedia page? Thanks guys. Nice work.

[NereusRen]

Oh, for the love of...

Editors, if you link a Wikipedia page from the summary, PLEASE link a historical revision. That way, whatever vandalism happens won't affect the link, and thus fewer people will be tempted to even vandalize at all.

Seriously, do the editors have any sense at all? It's not like this is a new problem.

Re:huh

[raka]

You intuation is right.

They cool thing about BEC is that it violates that intuition. Until B&E published, everyone thought that "much higher than zero kelvin" meant when that (in the appropriate units) the temperature (i.e. roughly the average energy per particle) had to be (much) less than the difference in energy between lowest state and any of the the others. If you think about this assumption, you will see that it nearly comes from
Bolzman's law (and if you don't know what Boltzman's law is, and are not a science or engineering student, you probably don't care).

Satyendranath (sp?) Bose came up with the bombshell that although Bolztman's law is right Bolztman's law operates differently for quantum particles. Some quantum particles (nowadays called Bosons) are more likely than expected to get into the same quantum state. They will do this wheneve the temperature is low enough
that their momentum uncertainty forces their position uncertainty to be at least as large as the typical distance between partciles (i.e their wavefunctions must "overlap" coherently, and again if you don't understand, you don't care).

So even ordinary BECs happen at relatively high temeratures. Unfortunately these temperatures are still in the nanokelvin range, at least for atoms under experimental conditions.