We theoretically study the collision-induced constructive quantum interference in an open four-level system with the density-matrix approach based on the experimental observation of constructive quantum interference between two transition pathways ${3P}_{1/2}\ensuremath{-}5S$ (or
4D) and ${3P}_{3/2}\ensuremath{-}5S$ (or
4D) via equal-frequency hybrid excitation in the ${\mathrm{Na}}_{2}\ensuremath{-}\mathrm{Na}$ system. The effects of the collision-induced coherent and incoherent decay rates and the ratio of the two transition dipole moments on the interference are analyzed. It is shown that through the incoherent process (collision), the coherence between a widely separated doublet and subsequent constructive quantum interference can be realized. The physical origin of the constructive interference can be seen clearly in the dressed-atom picture. The theoretical results can also be used to qualitatively explain the dependence of quantum interference on the experimental buffer gas pressure and sample temperature.
Exploiting quantum interference presents a significant challenge in ultracold inelastic scattering. In this study we propose a method to verify quantum interference within the two-body loss rate that arises from multiple inelastic-scattering channels, where the colliding particles are initially prepared in their individual hyperfine states. Our approach employs a ring-coupling configuration, accomplished by combining external radio-frequency and static electric fields during ultracold atomic collisions. To validate our proposal, we perform close-coupling calculations for $^{7}\mathrm{Li}\text{\ensuremath{-}}^{41}\mathrm{K}$ collisions at the ultracold limit. The results reveal that the interference profile, as manifested in the two-body loss rate, can be verified with optimized external field parameters. Notably, our findings indicate that the two-body loss rate coefficient exhibits a distinct pattern of constructive or destructive interference when crossing a magnetically induced
p-wave resonance in the incoming channel. These interference patterns become increasingly pronounced as the intensities of the external fields increase. This work presents a potential approach to controlling inelastic-scattering processes in ultracold collisions.