Blue-Detuned Magneto-optical Trap of Molecules

Direct laser cooling of molecules has reached a phase-space density exceeding 10⁻⁶ in optical traps but
with rather small molecular numbers. To progress toward quantum degeneracy, a mechanism that combines
sub-Doppler cooling and magneto-optical trapping would facilitate near unity transfer of ultracold
molecules from the magneto-optical trap (MOT) to a conservative optical trap. Using the unique energy
level structure of YO molecules, we demonstrate the first blue-detuned MOT for molecules that is