# Optical Molasses

by Niles
Tags: molasses, optical
 P: 3 Yes. The Doppler limit can be derived by considering the interplay between the optical molasses cooling force and the heating effect of random spontaneous emission. The spontaneous emission can be modeled as a random walk in momentum space with steps of $\hbar k$. Nowhere in this derivation is the polarization of the beams relevant. However, the counter-propagating beams do have a polarization, and this polarization can be used in conjunction with the atoms' magnetic structure to realize sub-Doppler temperatures. In this case, the polarization of the beams is highly relevant.