Encyclopedia … combined with a great Buyer's Guide!

Sponsors:     and others

Sisyphus Cooling

Definition: a mechanism for laser cooling of atoms or ions

More general term: laser cooling

German: Sisyphos-Kühlung

Categories: quantum optics, methods


How to cite the article; suggest additional literature

URL: https://www.rp-photonics.com/sisyphus_cooling.html

Sisyphus cooling (or Sisyphos cooling) is a mechanism for laser cooling of atoms or ions using light forces. It was understood in 1985 that the simple mechanism of Doppler cooling is not a sufficient explanation for experimental findings in laser cooling experiments with cesium atoms, where temperatures well below the Doppler limit were observed.

The mechanism of Sisyphus cooling is somewhat sophisticated. It involves a polarization gradient, as generated e.g. by two counterpropagating linearly polarized laser beams with perpendicular polarization directions (lin ⊥ lin configuration), and is therefore sometimes called polarization gradient cooling. The full explanation is based on the picture of dressed states [1]. An essential ingredient is that when atoms in a certain dressed state “climb uphill”, i.e. reach a position where their potential energy is relatively large, it becomes likely that they are optically pumped into another state for which the potential energy at that position is close to a minimum. In such a way, the polarization gradient introduces non-conservative light forces, which can reduce the average kinetic energy of atoms.

Sisyphus cooling has become important for optical frequency standards because it makes it possible to cool atoms to very low temperatures (“sub-Doppler temperatures”), so that the linewidth of certain forbidden transitions becomes very small.


[1]J. Dalibard and C. Cohen-Tannoudji, “Dressed-atom approach to atomic motion in laser light: the dipole force revisited”, J. Opt. Soc. Am. B 2 (11), 1707 (1985), DOI:10.1364/JOSAB.2.001707

See also: laser cooling, Doppler cooling, Doppler limit, recoil limit, optical frequency standards, frequency metrology

Questions and Comments from Users

Here you can submit questions and comments. As far as they get accepted by the author, they will appear above this paragraph together with the author’s answer. The author will decide on acceptance based on certain criteria. Essentially, the issue must be of sufficiently broad interest.

Please do not enter personal data here; we would otherwise delete it soon. (See also our privacy declaration.) If you wish to receive personal feedback or consultancy from the author, please contact him, e.g. via e-mail.

Your question or comment:

Spam check:

  (Please enter the sum of thirteen and three in the form of digits!)

By submitting the information, you give your consent to the potential publication of your inputs on our website according to our rules. (If you later retract your consent, we will delete those inputs.) As your inputs are first reviewed by the author, they may be published with some delay.


Share this with your friends and colleagues, e.g. via social media:

These sharing buttons are implemented in a privacy-friendly way!

Code for Links on Other Websites

If you want to place a link to this article in some other resource (e.g. your website, social media, a discussion forum, Wikipedia), you can get the required code here.

HTML link on this article:

<a href="https://www.rp-photonics.com/sisyphus_cooling.html">
Article on Sisyphus cooling</a>
in the <a href="https://www.rp-photonics.com/encyclopedia.html">
RP Photonics Encyclopedia</a>

With preview image (see the box just above):

<a href="https://www.rp-photonics.com/sisyphus_cooling.html">
<img src="https://www.rp-photonics.com/previews/sisyphus_cooling.png"
alt="article" style="width:400px"></a>

For Wikipedia, e.g. in the section "==External links==":

* [https://www.rp-photonics.com/sisyphus_cooling.html
article on 'Sisyphus cooling' in the RP Photonics Encyclopedia]