Laser cooling of rotation and vibration by optical pumping

Abstract

We have recently demonstrated that optical pumping methods combined with photoassociation of ultra-cold atoms can produce ultra-cold and dense samples of molecules in their absolute rovibronic ground state. More generally, both the external and internal degrees of freedom can be cooled by addressing selected rovibrational levels on demand. Here, we recall the basic concepts and main steps of our experiments, including the excitation schemes and detection techniques we use to achieve the rovibrational cooling of Cs 2 molecules. In addition, we present the determination of formation pathways and a theoretical analysis explaining the experimental observations. These simulations improves the spectroscopic knowledge required to transfer molecules to any desired rovibrational level.

Cooling molecular vibrations with shaped laser pulses: optimal control theory exploiting the timescale separation between coherent excitation and spontaneous emission

“…This is more important for the symmetrized cooling since in the assembly-line case, the leakage is (12), and its components versus iterations of the optimization algorithm (n max = 10). Optimizing the vibrational cooling of Cs 2 molecules using assemblyline cooling: value of the total functional, equation (15), and its components versus iterations of the optimization algorithm (n max = 10). much easier to prevent by virtue of the mechanism.…”

“…In particular, both algorithms converge monotonically (dashed blue lines in figures 6 and 7), the dark-state condition can be very well fulfilled (green long dashed lines) and the excitation is efficient (purple dot-dashed and black dotted lines). The behavior with respect to leakage changes dramatically, however, when going from Cs2 to LiCs (red lines in figures 6 and 7): J leak takes final values of 0.16 for symmetrized 1 10 100 1000 iteration Optimizing the vibrational cooling of LiCs molecules using assemblyline cooling: value of the total functional, equation (15), and its components versus iterations of the optimization algorithm (n max = 5).…”

“…with the 'initial' condition at time t = T given by the derivatives of the final-time functional, equation (12) or (15), with respect to ψ n |, evaluated using the final-time forward propagated states, |ψ (i) n (T ) .…”

“…Similar to equation (12), the complete final-time functional for assembly-line cooling is given by summing all contributions J ass T = λ ss J ss + λ leak J leak + λ yieldJ yield + λ ass J ass (15) with weights λ j > 0. In equation (12), heating is countered only via the leakage term, whereas equation (15) avoids it actively.…”

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.…”