Einat Frishman

Theory of radiative recombination with strong laser pulses and the formation of ultracold molecules via stimulated photo-recombination of cold atoms

A time dependent theory for radiative recombination induced by strong pulses is presented. Analytic solutions in the adiabatic limit are derived and found to be in excellent agreement with exact numerical solutions. Both the pump-before-dump “intuitive” and dump-before-pump “counter-intuitive” schemes are considered. Resonantly enhanced two-photon recombination of ultracold atoms is shown to be an efficient mechanism for the production of ultracold molecules. We have performed detailed calculations on the radiative recombination of cold Na atoms by short laser pulses. Our calculations show that, per pulse, it is possible for up to 97% of all head-on Na-Na colliding pairs to end up as v=0, J=0 translationally cold Na2 molecules. We show that these findings, translated to thermally cooled ensemble conditions, mean that the fraction of Na atoms at μKelvin which can be recombined by a pulse of 20 ns duration and 108 W/cm2 peak intensity, to form J=0 molecules is 6×10−6 per pulse. With the above parameters, a ...

Enantiomeric purification of nonpolarized racemic mixtures using coherent light

Angular momentum constraints for coherently controlling chiral purification of racemic mixtures using the dipole-electric field interaction are examined in detail for two different scenarios. First shown is that achieving enantiomeric control in our earlier scheme [M. Shapiro, E. Frishman, and P. Brumer, Phys. Rev. Lett. 84, 1669 (2000)], using parallel laser pulses, requires that the system be M-polarized, where M is the projection of the total angular momentum along the axis of laser polarization. An alternate scenario is then introduced that allows chiral control in an unpolarized racemic mixture by using three mutually perpendicular linearly polarized light fields. Analytic expressions for the enantiomeric excess in both cases are derived and computational results are presented.

Coherent enhancement and suppression of reactive scattering and tunneling

An optimization approach to coherent control of scattering is introduced and used to show that one can totally suppress reaction at energy E if the number of populated initial states exceeds the number of open product states (as in endoergic reactions). Numerical results on a multichannel system are presented.

Optical purification of racemic mixtures by 'laser distillation' in the presence of a dissipative bath

Optical purification of a mixture of chiral molecules in the presence of dissipation is examined. Specifically, the case where dissipation occurs on timescales comparable to those of the laser pulses is treated. The interplay between a strong driving field and decoherence and the extent to which control is possible in the presence of dissipation and decoherence is elucidated.