Methods of cooling matter to extremely low temperatures


by InFlames4ever
Tags: cooling, extremely, matter, methods, temperatures
InFlames4ever
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#1
Nov7-12, 03:59 PM
P: 2
I am trying to find out as many ways of cooling down matter as possible and information on said ways, so far I have found out a bit about laser cooling, evaporative cooling and that's about it. I'm sure there are other ways but I can't find any and the information I can find on these ways is either not in enough detail or too advanced for my level of understanding. I have an A-level in physics but no further so that would be my ability level.
Any help would be appreciated, thanks.
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Zarqon
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#2
Nov8-12, 02:45 AM
P: 217
You have to specify more details on what "matter" you want to cool down and how far down you need to go. For larger pieces of matter, like solids, the most common form of cooling is by liquid nitrogen and liquid helium, which can get you down to 1-2 K. Further use of a dilution fridge can get you down to the milikelvin range.

For small samples of trapped atoms or ions, laser cooling (doppler cooling) works, which can be combined with resolved sideband techniques to reach few phonon number states (temperature then depends on level structure).

So, what system are you looking at, annd how cold do you need to be?
InFlames4ever
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#3
Nov8-12, 02:13 PM
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Well I'm talking about ways of getting near to absolute zero, and I can't believe I didn't put that in the OP. I'm also talking about gases mainly.

Rajini
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#4
Nov9-12, 06:34 AM
P: 597

Methods of cooling matter to extremely low temperatures


Hi,
I am not well sure about minimum possible experiments..but some research group in Finland did some experiments in the range of 30 mK..they obtained by mixing two different liquid helium (He I and II if i remember good..)..
f95toli
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#5
Nov9-12, 07:10 AM
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Quote Quote by Rajini View Post
Hi,
I am not well sure about minimum possible experiments..but some research group in Finland did some experiments in the range of 30 mK..they obtained by mixing two different liquid helium (He I and II if i remember good..)..
30 mK is the base temperature of a (bad) diliution refrigerator. Commerical diluition refrigerators can reach about 10 mK or so. Once there you can use an adiabatic degmagnetization stage to go lower, below 1mK to say a few hundered microkelvin.
Note that we are talking about cooling large chuncks of matter, several kilograms.

For gases you need laser cooling, look up experiments on Bose-Einstein condensatates.
Zarqon
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#6
Nov9-12, 09:47 AM
P: 217
It would also help if you specified what atoms your gas consists of and how it is confined, since for laser cooling for example you are dependent on finding a closed cooling cycle that can be repeated without branching losses and similar.


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