Perspectives for coherent optical formation of strontium molecules in their electronic ground state

Abstract

Optical Feshbach resonances and pump-dump photoassociation with short laser pulses have been proposed as means to coherently form stable ultracold-alkali-metal dimer molecules. In an optical Feshbach resonance, the intensity and possibly frequency of a cw laser are ramped up linearly followed by a sudden switch-off of the laser. This is applicable to tightly trapped atom pairs. In short-pulse photoassociation, the pump pulse forms a wave packet in an electronically excited state. The ensuing dynamics carries the wave packet to shorter internuclear distances where, after half a vibrational period, it can be deexcited to the electronic ground state by the dump pulse. Short-pulse photoassociation is suited for both shallow and tight traps. The applicability of these two means to produce ultracold molecules is investigated here for Sr88. Dipole-allowed transitions proceeding via the B Σu+ 1 excited state as well as transitions near the intercombination line are studied. © 2008 The American Physical Society.