Nobel Prize In Physics For Bose-Einstein Condensate

LMCBoy writes "The Royal Swedish Academy of Sciences announced the 2001 Nobel Prize in Physics today. The award went to scientists who managed to construct a Bose-Einstein condensate from Rubidium and Sodium atoms. The process involves cooling the atoms to about 20 nanoKelvin. From the press release: 'A laser beam differs from the light from an ordinary light bulb in several ways. In the laser the light particles all have the same energy and oscillate together. To cause matter also to behave in this controlled way has long been a challenge for researchers. This year's Nobel Laureates have succeeded - they have caused atoms to "sing in unison" - thus discovering a new state of matter, the Bose-Einstein condensate.'" This is the same reasearch that Hemos recently posted about.

Comments

How to do it

[hardburn]

Rubidium and sodium have the intresting property that, when combined, they condense at around 35 kilojoules, very close to the famed Velhany constant.

However, it is also very difficult to find these two atoms in a pure form. The only good way to do it is to spin basic molecules containing these two elements through xeon gas within a 20 megagauss accellerator, of which there is only two in the world. Once you have them, it is very hard to keep them from combining with other elements again. You must immediatly cool them to around 3 Kelvin or you'll have to start all over again.

To actualy produce temperatures like 20 nano Kelvin, you can't use other materials (such as liquid nitrogen). The best way is to use two large magnets and a laser. If aligned properly, the magnets will actualy bend the laser around the atoms, producing a sort of barrier that will not allow energy in, but will allow it to escape. The magnets have the secondary effect of helping suck energy out of the material.

(Yes, I made all this up. I want to see how many people slashdotters flame me for all this BS when they haven't read this far down. Yes, I have karma to burn.)

Most interesting property of BECs

[Macrobat]

I thought the big deal about Bose-Einstein condensates was their indeterminate size. Since cooling matter down to nearly absolute zero halts motion, and since zero motion is a very measurable quantity, Heisenberg's uncertainty principle means that the actual location of the electrons becomes indeterminate, and therefore the size of the atomic shell grows bigger. Not sure what implications this fact has, though, but it's kinda neat. If anything ever were to be cooled to absolute zero, it would be of infinite size.

Re:Most interesting property of BECs

[shawnseat]

Since cooling matter down to nearly absolute zero halts motion

Bzzt. At near absolute zero you approach what is called "zero-point motion". Quantum mechanical oscillators still vibrate at their lowest energy level (their energy being (1/2)*h*(frequency)). So even at absolute zero you don't have electrons flying all over the place. (Actually, room temperature is virtually absolute zero on an electronic basis anyway -- most electronic excited states are effectively in the thousands of kelvin).