In Sisyphus cooling, the two Zeeman levels of a J = 1 / 2 atomic ground state manifold experience equal and opposite AC Stark shifts from the near-resonant counter-propagating beams. The beams also effect a polarization gradient, alternating between linear and circular polarizations. The potential energy maxima of one m J coincide with pure circular polarization, which optically pumps atoms to the other m J , which experiences its minima in the same location. Over time, the atoms expend their kinetic energy traversing the potential energy landscape and transferring the potential energy difference between the crests and troughs of the AC-Stark-shifted ground state levels to emitted photons.