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en-wikipedia-org-6541		Sisyphus cooling - Wikipedia			.html	text/html	1440	251	80	Physical principle of Sisyphus cooling: The atoms are running against the potential energy, become excited into a higher band, fall back into a low-energy state (i.e. from the rather high "blue" state upwards, then immediately backwards to the lower "red" state), always on the left-hand side, from which, after one and a half of the "red" or "blue" period, say, of the laser action, they get excited and de-excited again, now from "red" to "blue", on the r.h.s., etc. Sisyphus cooling (sometimes called polarization gradient cooling) is a type of laser cooling of atoms used to reach temperatures below the Doppler cooling limit. This cooling method was first proposed by Claude Cohen-Tannoudji in 1989,[1] motivated by earlier experiments which observed sodium atoms cooled below the Doppler limit in an optical molasses.[2] Cohen-Tannoudji received part of the Nobel Prize in Physics in 1997 for his work. Sisyphus cooling can be achieved by shining two counter-propagating laser beams with orthogonal polarization onto an atom sample.	./cache/en-wikipedia-org-6541.html	./txt/en-wikipedia-org-6541.txt