Molecular cooling via Sisyphus processes

Abstract

We present a study of Sisyphus cooling of molecules: the scattering of a single-photon remove a substantial amount of the molecular kinetic energy and an optical pumping step allow to repeat the process. A review of the produced cold molecules so far indicates that the method can be implemented for most of them, making it a promising method able to produce a large sample of molecules at sub-mK temperature. Considerations of the required experimental parameters, for instance the laser power and linewidth or the trap anisotropy and dimensionality, are given. Rate equations, as well as scattering and dipolar forces, are solved using Kinetic Monte Carlo methods for several lasers and several levels. For NH molecules, such detailed simulation predicts a 1000-fold temperature reduction and an increase of the phase space density by a factor of 10 7 . Even in the case of molecules with both low Franck-Condon coefficients and a non-closed pumping scheme, 60% of trapped molecules can be cooled from 100 mK to sub-mK temperature in few seconds. Additionally, these methods can be applied to continuously decelerate and cool a molecular beam

Laser Cooling of Molecular Anions

“…The first one is "standard" laser cooling in the gas phase (thus with no strong external fields present); the second one is laser cooling in a Paul trap; and the last one is Sisyphus cooling o f trapped ions in a Penning trap. The sim ulations are perform ed with the C + + code described in [28], which now also includes full A -bcdy space charge effects [33]; the Lorentz force is solved by using Boris-Bunem an integration algorithm s [34,35] Fig. 1(a).…”

“…For this reason, these anions are not stable against autodetachment processes and exhibit pure rovibrational transitions with ~100 ms lifetimes. Even if such long-lived states can still be of interest for Sisyphus cooling, for narrow-line cooling, or for Doppler laser cooling in traps [26,28], pure electronic transitions are preferred for rapid laser cooling. Transitions of ~100 ns lifetime can be found between well-separated electronic states (typically B X states), whereas transitions in the infrared region between electronic states (typically A <+ X states) have longer lifetimes of ~ 100 ps.…”

Overview of Recent Work on Laser Excitation of Positronium for the Formation of Antihydrogen

“…The positron system, mainly composed by a 22 Na radioactive source and two Surko-like traps to cool and accumulate positrons can deliver positrons toward either the main apparatus or the test chamber. In spring 2015 when the measurements presented here have been performed, the source had an intensity of around 11mCi, and the system was able to typically provide bunches of 8 10 7 e + every 3 minutes.…”

“…The N-body Colombian interactions, the Lorentz and gravity forces are taken into account. A full description of the code can be found in [22]. In Fig.…”

Photoassociative cooling and trapping of a pair of interacting atoms

“…Our proposed scheme may be compared to Sisyphus laser cooling of diatomic molecules [46,49,50]. The c.m.…”