Cryogenics: How can we achieve temperature upto 4 kelvin

Ya Cyrogenic refrigerants are used to porduce very low temperatures from -53 to -273C . Temp. upto 4k can be obtained in special labs only recently I read that a scientist has claimed to have achieved a temp. of -272.5C which is very near to absolute zero when everything ceases.

Man, some people just aren't happy until thier beer is really, really cold!

I think google books has a book on cyrocoolers - which is what I think you are looking for. You can achieve this by stacking cyrocoolers. NASA, JPL, and Los Almos have posted some research on the subject. If power inputs, time, and cash aren't a problem, you can probably do it. If you have access to some liquids like He@ N2 or even CO2 you can probably cut a few corners. Of course at 4K, you are going to have issues with your materials. do a keyword search on cyrocooler and see what you come up with.