Feshbach-optimized photoassociation of ultracold $^6$Li$^{87}$Rb molecules with short pulses

Abstract

Two-color photoassociation of ground state $^6$Li$^{87}$Rb molecules via the $\mathrm{B}^1\Pi$ electronic state using short pulses near a magnetic Feshbach resonance is studied theoretically. A near-resonant magnetic field is applied to mix the hyperfine singlet and triplet components of the initial wave function and enhance the photoassociation rate, before the population is transferred to the ground state by a second pulse. We show that an increase of up to three orders of magnitude in the absolute number of molecules produced is attainable for deeply bound vibrational levels. This technique can be generalized to other molecules with accessible magnetic Feshbach resonances.