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Laser Coolingl Trapping and Control of Atoms
Published in Yu. N. Kulchin, Modern Optics and Photonics of Nano and Microsystems, 2018
The desire to achieve lower cooling temperatures of atoms led to the search for new methods based on the modification of the Doppler cooling method. One of their varieties is the so‐called ‘Sisyphus cooling’, in which the atom, like the mythical Greek hero, reaching the top of the periodic potential relief, periodically rolls down, losing energy and cooling.
Ro-vibrational cooling of diatomic molecules Cd2 and Yb2: rotational energy structure included
Published in Molecular Physics, 2020
Tomasz Urbańczyk, Jarosław Koperski
There exist techniques of ro-vibrational cooling that are based on interaction of molecules with laser radiation employing, for example, optical pumping or so-called Sisyphus cooling. The methods that use optical pumping are based on the concept of a luminorefrigeration proposed by Kastler in 1950 [13]. Since then, many cooling methods for different diatomic molecules were proposed. The reader is referred to the seminal article of Di Rosa [14] where plans for laser-cooling of molecules are presented. Further reviews by Carr et al. [15] and Bohn et al. [16] present progress in the field. DeMille's group demonstrated laser cooling of SrF in radio-frequency MOT [17,18]. Recently, molecules with complex level structure have drawn particular attention as good candidates for trapping in MOTs [19] or direct laser cooling [20]. Consequently, SrF molecules have been laser-cooled below the Doppler limit [21] and for ultracold CaF magnetically trapped in a single quantum state, coherent microwave control of the rotational, hyperfine and Zeeman levels has been demonstrated [22]. Another important step was realisation of an efficient laser-cooling of optically trapped CaF well below the Doppler limit [23].
Laser cooling of rubidium atoms in a 2D optical lattice
Published in Journal of Modern Optics, 2018
Chunhua Wei, Carlos C. N. Kuhn
The most commonly used method to trap and cool neutral atoms is the magneto-optical trap (MOT), a configuration of red detuned lasers and a quadrupole magnetic field [13]. The MOT is designed to harness the Doppler effect to cool a large number of atoms to the Doppler limit, , where is the laser cooling transition linewidth (typically around 210 MHz for alkali atoms) and is the Boltzmann constant, with temperatures around predicted (for Rb atoms where the transition linewidth is the ). Experimental application of the MOT was found to cool atoms significantly below this limit, through a process termed Sisyphus cooling. This process arises through a combination of optical pumping and the polarization gradients experienced by the atoms moving through the optical field of the MOT beams, allowing significantly more energy to be extracted from the laser cooled atoms and leading to temperatures over an order of magnitude less than Doppler cooling [14]. This technique became known as polarization Gradient Cooling (PGC).