Quantum interference effects in stereodynamically prepared cold He+D₂ collisions

In a recent experiment using the Stark-induced Adiabatic Raman Passage (SARP) technique, Zhou et al. [J. Chem. Phys. 154, 104309 (2021); Science 374, 960 (2021)] reported angular distributions for  pure rotational quenching of D₂ from j=2 to 0 in the v=2 vibrational level. The differential cross sections for this process for different initial stereodynamic preparation of the molecular bond-axis alignment relative to the SARP laser polarization revealed that the angular distribution is dominated by a l=2 partial wave, suggesting the possibility of a shape resonance near 1 K that controls the collision dynamics. Here we report explicit quantum scattering calculations of He+D₂ collisions on a highly accurate interaction potential that reveal the presence of a weak l=2 resonance near 1 K in agreement with the experiment. However, our results uncover a much more intense l=1 shape resonance around 0.01-0.1 K that dominates the angular distribution when it is averaged  to reproduce the experimental velocity distribution.  Our results reproduce key features of the experimentally measured angular distributions when contributions from the l = 1 resonance are artificially suppressed.